JP2005038581A - Optical element and optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent reflection of luminous fluxes having wavelength of 390-430 nm and luminous fluxes having wavelength of 630-800 nm by the smaller number of antireflection films than the conventional number. <P>SOLUTION: An optical pickup device 1 for recording and/or reproducing information is provided with an objective lens 5. The objective lens condenses luminous fluxe of a plurality of wavelengths including a wavelength λ1 nm(390≤λ1≤430) and a wavelength λ2 nm(630≤λ2≤800), on an AOD 100 and a DVD 200. The objective lens 5 is provided with a lens main body 50 and antireflection films 51 which are provided on both surfaces of the lens main body and have optical functional surfaces 52 and 53 formed thereon. The reflectivity of a luminous flux perpendicularly made incident on optical functional surfaces 52 and 53 shows a maximum value equal to or larger than 1% between the wavelength λ1 and the wavelength λ2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical pickup device that records and / or reproduces information, and an optical element provided in the optical pickup device.

  Conventionally, as an information recording medium, a CD using a light beam having a wavelength of about 780 [nm], a DVD using a light beam having a wavelength of 635 to 650 [nm], an AOD (Advanced Optical using a light beam having a wavelength of about 405 [nm]. There have been developed optical pickup apparatuses that can be used for any information recording medium such as a disc or a blu-ray disc and an AOD or blu-ray disc and a DVD and / or CD. On the optical functional surface of an optical element such as an objective lens provided in the optical pickup device, an antireflection film for preventing the reflection of the light beam is provided.

  In general, the antireflection film has an antireflection function with respect to each light beam having a wide wavelength range, and has a wide wavelength range (hereinafter referred to as an antireflection wavelength range) where reflection should be prevented, or an optical element body. The number of layers is varied depending on the refractive index of the film, the target reflectance (hereinafter referred to as the target reflectance), and the like. Specifically, in an optical pickup apparatus that can handle AOD or Blu-ray disc and DVD, for example, the antireflection wavelength region is 400 to 650 [nm], and the refractive index of the optical element body is 1.5 to 1.6. In general, when the target reflectivity is 1 [%] or less, the antireflection film of the optical element is generally composed of 5 to 7 layers. Further, in an optical pickup device that can handle AOD or Blu-ray disc, DVD, and CD, when the antireflection wavelength region is 400 to 800 [nm], the antireflection film is composed of nine or more layers ( For example, see Patent Document 1).

  By the way, when the number of layers of the antireflection film is increased, there are problems that production costs increase, and moisture permeates between layers to change spectral characteristics. In particular, when the optical element body is made of optical plastic, cracks occur in the antireflection film due to the stress of the antireflection film itself, or the adhesion between the antireflection film and the optical element body decreases. There is a problem that the environmental resistance is lowered.

Therefore, in order to solve such a problem, there is a technique for forming an antireflection film with a small number of layers of 3 to 7 by limiting the wavelength at which the reflectance is 1% or less to only two types of wavelengths. Yes (see, for example, Patent Document 2).
JP 2000-111702 A JP 11-167003 A

  However, the technique disclosed in Patent Document 2 prevents reflection of a light beam having a wavelength of 150 to 300 [nm] and a light beam having a wavelength of 400 to 800 [nm], and has a wavelength of 390 to 430 [nm]. It does not prevent reflection of a light beam having a wavelength and a light beam having a wavelength of 630 to 800 [nm].

  An object of the present invention is an optical which can prevent reflection of a light beam having a wavelength of 390 to 430 [nm] and a light beam having a wavelength of 630 to 800 [nm] with an antireflection film having a smaller number of layers than conventional ones. It is providing an element and an optical pick-up apparatus provided with this optical element.

The invention according to claim 1 is provided in an optical pickup device that records and / or reproduces information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 800 [nm]), an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body to form at least one optical functional surface,
The reflectance of the light beam perpendicularly incident on the optical function surface exhibits a maximum value of 1% or more between the wavelength λ1 and the wavelength λ2.

  Here, a plurality of wavelengths are two or more types of wavelengths. Further, the interval between the wavelength λ1 and the wavelength λ2 is a range longer than the wavelength λ1 and shorter than the wavelength λ2.

According to the first aspect of the present invention, the reflectivity of the light beam perpendicularly incident on the optical function surface exhibits a maximum value of 1% or more between the wavelength λ1 and the wavelength λ2, and thus the light beam having the wavelength λ1 and the wavelength Reflectance is relatively low with respect to the light beam of λ2, and reflection is prevented. Therefore, unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of the wavelengths λ1 to λ2 by the amount that the antireflection function is reduced between the wavelengths λ1 and λ2, the wavelength λ1 The number of antireflection films can be reduced without impairing the antireflection function for the light flux and the light flux of wavelength 2. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

  In addition, it is preferable that the reflectance of the light beam perpendicularly incident on the optical function surface exhibits a maximum value of 2% or more between the wavelength λ1 and the wavelength λ2.

The invention according to claim 2 is the optical element according to claim 1,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The wavelength λ2 is characterized in that 630 [nm] ≦ λ2 ≦ 670 [nm].

  According to the second aspect of the present invention, the reflection of the light beam having the use wavelength λ1 of the AOD or the Blu-ray disc, the light beam having the use wavelength λ2 of the DVD, and the light beam having the use wavelength λ3 of the CD is reduced. Can be prevented.

Invention of Claim 3 is the optical element of Claim 1 or 2,
The maximum incident / exit angle θmax of the light flux having the wavelength λ1 on the optical function surface is 0 [°] ≦ θmax ≦ 40 [°].

  According to the third aspect of the present invention, it is possible to accurately record and reproduce information using a light flux of 0 [°] ≦ θmax ≦ 40 [°].

Invention of Claim 4 is an optical element as described in any one of Claims 1-3,
The refractive index n ₀ of the optical element body is 1.45 ≦ n ₀ ≦ 1.65,
Of the layers included in the antireflection film, the first layer located closest to the optical element body has a refractive index n ₁ of 1.7 ≦ n ₁ ≦ 2.5 and an optical film thickness nd ₁ of 225 [nm. ] ≦ nd ₁ ≦ 275 [nm],
Second, the second layer located on the optical element body side has a refractive index n ₂ of 1.3 ≦ n ₂ ≦ 1.55 and an optical film thickness nd ₂ of 100 [nm] ≦ nd ₂ ≦ 150 [nm]. It is characterized by being.

Here, the optical film thickness is a value represented by film thickness × refractive index [nm], and the film thickness is the thickness in the normal direction of the surface of the optical element body.
According to the fourth aspect of the present invention, since the first layer and the second layer can prevent the reflection of the light flux of each wavelength, the number of layers of the antireflection film can be reduced without impairing the antireflection function. it can.

Invention of Claim 5 is an optical element as described in any one of Claims 1-3,
The refractive index n ₀ of the optical element body is 1.45 ≦ n ₀ ≦ 1.65,
Of the layers included in the antireflection film, the first layer located closest to the optical element body has a refractive index n ₁ of 1.7 ≦ n ₁ ≦ 2.5 and an optical film thickness nd ₁ of 125 [nm. ] ≦ nd ₁ ≦ 175 [nm],
Second, the second layer located on the optical element body side has a refractive index n ₂ of 1.55 ≦ n ₂ <1.7 and an optical film thickness nd ₂ of 75 [nm] ≦ nd ₂ ≦ 125 [nm]. And
Third, the third layer located on the optical element body side has a refractive index n ₃ of 1.3 ≦ n ₃ <1.55 and an optical film thickness nd ₃ of 100 [nm] ≦ nd ₃ ≦ 150 [nm]. It is characterized by being.

  According to the fifth aspect of the present invention, since the first layer, the second layer, and the third layer can prevent the reflection of the light flux of each wavelength, the number of antireflection films can be reduced without impairing the antireflection function. Can be reduced.

Invention of Claim 6 is set in the optical element as described in any one of Claims 1-3,
The refractive index n ₀ of the optical element body is 1.45 ≦ n ₀ ≦ 1.65,
Of the layers included in the antireflection film, the first layer located closest to the optical element body has a refractive index n ₁ of 1.7 ≦ n ₁ ≦ 2.5 and an optical film thickness nd ₁ of 25 [nm. ] ≦ nd ₁ ≦ 75 [nm],
Second, the second layer located on the optical element body side has a refractive index n ₂ of 1.3 ≦ n ₂ ≦ 1.55 and an optical film thickness nd ₂ of 25 [nm] ≦ nd ₂ ≦ 75 [nm]. And
Third, the third layer located on the optical element body side has a refractive index n ₃ of 1.7 ≦ n ₃ ≦ 2.5 and an optical film thickness nd ₃ of 225 [nm] ≦ nd ₃ ≦ 275 [nm]. And
The fourth layer located fourth on the optical element body side has a refractive index n ₄ of 1.3 ≦ n ₄ ≦ 1.55 and an optical film thickness nd ₄ of 135 [nm] ≦ nd ₄ ≦ 185 [nm]. It is characterized by being.

  According to the sixth aspect of the invention, the first layer, the second layer, the third layer, and the fourth layer can prevent the reflection of the light flux of each wavelength, so that the antireflection film is not impaired without impairing the antireflection function. The number of layers can be reduced.

The invention according to claim 7 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is 5% or less. Forming at least two optical functional surfaces having a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

According to the seventh aspect of the present invention, when the wavelength λ of the light beam perpendicularly incident on the optical function surface is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm] Since the reflectance on the optical function surface is 1% or less, reflection can be prevented for wavelengths in these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike a conventional antireflection film that prevents reflection of the entire light beam in a wide wavelength range of λ1 to λ2, the number of layers of the antireflection film without impairing the antireflection function for the light beam of wavelength λ1 and the light beam of wavelength 2 Can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

  In addition, {(maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (minimum film thickness within the effective diameter)} / average film thickness value with respect to the surface of the optical element body having a large numerical aperture As a method of forming an antireflection film so that the ratio is 5% or less, a method of attaching a self-revolving jig to a vapor deposition apparatus for depositing the antireflection film, or a method of forming a film by a CVD (Chemical Vapor Deposition) method There is also a method of adjusting the atmospheric pressure higher. In addition, when the antireflection film is formed in this way, if the optical film thickness of the antireflection film is larger than the operating wavelength, the incident angle of the light beam may change and the spherical aberration may deteriorate. It is preferable to measure the transmitted wavefront of the optical element after coating, correct the mold for molding the optical element body, or design the optical element body in advance to cancel the spherical aberration of the antireflection film. .

The invention according to claim 8 is the optical element according to claim 7,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface is:
When the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance is 1 [%] or less.

  According to the eighth aspect of the present invention, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectivity on the optical function surface is 1% or less, so that the wavelength within this band is reduced. Again, reflection can be prevented.

The invention according to claim 9 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is 5% or less. Forming at least two optical functional surfaces having a maximum incident / exit angle θmax within the effective diameter of 40 [°] <θmax <90 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

According to the ninth aspect of the present invention, when the wavelength λ of the light beam perpendicularly incident on the optical functional surface is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm] Since the reflectance on the optical function surface is 1% or less, reflection can be prevented for wavelengths in these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike a conventional antireflection film that prevents reflection of the entire light beam in a wide wavelength range of λ1 to λ2, the number of layers of the antireflection film without impairing the antireflection function for the light beam of wavelength λ1 and the light beam of wavelength 2 Can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 10 is the optical element according to claim 9,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface is:
When the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less.

  According to the tenth aspect of the present invention, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance on the optical function surface is 1% or less. However, reflection can be prevented.

The invention according to claim 11 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is 5% or less. The first optical function surface having a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°], and the maximum incident / exit angle θmax within the effective diameter of 40 [°] < and at least one second optical functional surface satisfying θmax <90 [°],
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

According to the invention of claim 11, when the wavelength λ of the light beam perpendicularly incident on the first optical function surface is λ1 ≦ λ ≦ λ1 + 15 [nm], and when λ2 ≦ λ ≦ λ2 + 15 [nm]. In the case where the reflectance at the first optical functional surface is 1% or less and the wavelength λ of the light beam incident perpendicularly to the second optical functional surface is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ In the case of λ ≦ λ2 + 40 [nm], the reflectance at the second optical function surface is 1 [%] or less, and therefore reflection can be prevented for wavelengths in these bands. Further, in the first optical function surface, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], and the second optical function In terms of function, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is reduced. Unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of wavelengths λ1 to λ2, the antireflection film can be used without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 12 is the optical element according to claim 11,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm],
The second optical functional surface has a reflectance of 1 [%] or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm].

  According to the twelfth aspect of the invention, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance at the first optical functional surface is 1% or less, and the wavelength λ is λ3 When ≦ λ ≦ λ3 + 30 [nm], the reflectance at the second optical functional surface is 1% or less, and therefore reflection can be prevented even for wavelengths in these bands.

The invention according to claim 13 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed such that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ Forming at least two optical functional surfaces of 40 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

Here, the surface angle is an angle formed by the normal of the optical function surface and the optical axis.
According to the invention of claim 13, when the wavelength λ of the light beam perpendicularly incident on the optical function surface is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm] Since the reflectance in the optical functional surface is 1 [%] or less, reflection can be prevented for wavelengths in these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike a conventional antireflection film that prevents reflection of the entire light beam in a wide wavelength range of λ1 to λ2, the number of layers of the antireflection film without impairing the antireflection function for the light beam of wavelength λ1 and the light beam of wavelength 2 Can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 14 is the optical element according to claim 13,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface has a reflectance of 1 [%] or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm].

  According to the fourteenth aspect of the present invention, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance in the optical function surface is 1 [%] or less. Reflection can also be prevented.

The invention according to claim 15 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] <θ⊥max < 90 [°]
Or forming at least two optical functional surfaces satisfying 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

According to the invention described in claim 15, when the wavelength λ of the light beam perpendicularly incident on the optical function surface is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm] Since the reflectance on the optical functional surface is 1% or less, reflection can be prevented for wavelengths within these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance on the optical function surface shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Therefore, unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of wavelengths λ1 to λ2, the antireflection function is performed without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. The number of layers of the film can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 16 is the optical element according to claim 15,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface has a reflectance of 1 [%] or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm].

  According to the sixteenth aspect of the present invention, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance in the optical function surface is 1 [%] or less. Reflection can also be prevented.

The invention according to claim 17 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ At least one first optical functional surface of 40 [°];
0 [°] ≦ θmax ≦ 40 [°] and 40 [°] <θ⊥max <90 [°]
Or 40 [°] <θmax <90 [°] and at least one second optical functional surface satisfying 0 [°] ≦ θ⊥max ≦ 40 [°],
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength in the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

According to the seventeenth aspect of the present invention, there are a case where the wavelength λ of the light beam perpendicularly incident on the first optical function surface is λ1 ≦ λ ≦ λ1 + 15 [nm], and a case where λ2 ≦ λ ≦ λ2 + 15 [nm]. In the case where the reflectance at the first optical functional surface is 1% or less and the wavelength λ of the light beam incident perpendicularly to the second optical functional surface is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ In the case of λ ≦ λ2 + 40 [nm], the reflectance at the second optical function surface is 1 [%] or less, and therefore reflection can be prevented for wavelengths in these bands. Further, in the first optical function surface, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], and the second optical function In terms of function, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is reduced. Unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of wavelengths λ1 to λ2, the antireflection film can be used without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 18 is the optical element according to claim 17,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm],
The second optical functional surface has a reflectance of 1 [%] or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm].

  According to the invention of claim 18, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance at the first optical functional surface is 1% or less, and the wavelength λ is λ3 When ≦ λ ≦ λ3 + 30 [nm], the reflectance at the second optical function surface is 1 [%] or less, and therefore reflection can be prevented even for wavelengths within these bands.

The invention according to claim 19 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ At least one first optical functional surface of 40 [°];
40 [°] <θmax <90 [°] and at least one second optical functional surface satisfying 40 [°] <θ⊥max <90 [°], wherein the first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength in the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ2 + 130 [nm], the reflectance is 1.5 [%] or less.

According to the nineteenth aspect of the present invention, the case where the wavelength λ of the light beam perpendicularly incident on the first optical functional surface is λ1 ≦ λ ≦ λ1 + 15 [nm], and the case where λ2 ≦ λ ≦ λ2 + 15 [nm] are satisfied. In the case where the reflectance at the first optical function surface is 1% or less and the wavelength λ of the light beam perpendicularly incident on the second optical function surface is λ1 ≦ λ ≦ λ2 + 130 [nm], 2 Since the reflectance on the optical function surface is 1.5 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the first optical function surface, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. Unlike the above, the number of antireflection films can be reduced without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 20 is the optical element according to claim 19,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm],
The second optical functional surface has a reflectance of 1.5 [%] or less when the wavelength λ is λ1 ≦ λ ≦ λ3 + 120 [nm].

  According to the invention of claim 20, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance at the first optical functional surface is 1% or less, and the wavelength λ is λ1. When ≦ λ ≦ λ3 + 120 [nm], the reflectance at the second optical functional surface is 1.5 [%] or less, and therefore reflection can be prevented even for wavelengths within these bands. .

The invention according to claim 21 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] <θ⊥max < 90 [°]
Or at least one first optical functional surface satisfying 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°],
Forming at least one second optical functional surface satisfying 40 [°] <θmax <90 [°] and 40 [°] <θ⊥max <90 [°],
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ2 + 130 [nm], the reflectance is 1.5 [%] or less.

According to the invention of claim 21, when the wavelength λ of the light beam perpendicularly incident on the first optical functional surface is λ1 ≦ λ ≦ λ1 + 50 [nm], and when λ2 ≦ λ ≦ λ2 + 40 [nm] In the case where the reflectance on the first optical function surface is 1% or less and the wavelength λ of the light beam perpendicularly incident on the second optical function surface is λ1 ≦ λ ≦ λ2 + 130 [nm], 2 Since the reflectance on the optical function surface is 1.5 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the first optical function surface, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. Unlike the above, the number of antireflection films can be reduced without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 22 is the optical element according to claim 21,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm],
The second optical functional surface has a reflectance of 1.5 [%] or less when the wavelength λ is λ1 ≦ λ ≦ λ3 + 120 [nm].

  According to a twenty-second aspect of the present invention, when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the first optical functional surface is 1% or less, and the wavelength λ is λ1. When ≦ λ ≦ λ3 + 120 [nm], the reflectance at the second optical functional surface is 1.5 [%] or less, and therefore reflection can be prevented even for wavelengths within these bands. .

The invention described in claim 23 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
An optical element body, and an antireflection film provided on both surfaces of the optical element body and forming a first optical functional surface on the laser light source side and a second optical functional surface on the information recording medium side of the optical pickup device. Prepared,
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance exhibits a maximum value larger than 1 [%].

Here, the laser light source side and the information recording medium side are the laser light source side and the information recording medium side in the optical path of the used light beam.
According to the twenty-third aspect of the present invention, when the wavelength λ of the light beam perpendicularly incident on the first optical functional surface is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance on the first optical functional surface is 1 [ %] Or less, and when the wavelength λ of the light beam perpendicularly incident on the second optical function surface is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm] 2 Since the reflectance on the optical function surface is 1% or less, reflection can be prevented for wavelengths in these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance at the second optical function surface exhibits a maximum value larger than 1 [%], that is, an antireflection function. Therefore, unlike the conventional antireflection film that prevents reflection of the entire light flux in a wide wavelength range of wavelengths λ1 to λ2, the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2 is not impaired. The number of antireflection films can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 24 is the optical element according to claim 23,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less,
The second optical functional surface is
When the wavelength λ is λ2 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less.

  According to a twenty-fourth aspect of the invention, when the wavelength λ is λ1 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the first optical functional surface is 1% or less, and the wavelength λ is λ2. When ≦ λ ≦ λ3 + 30 [nm], the reflectance at the second optical function surface is 1 [%] or less, and therefore reflection can be prevented even for wavelengths within these bands.

The invention described in claim 25 is provided in an optical pickup device for recording and / or reproducing information, and has a wavelength λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and a wavelength λ2 (630 [nm] ≦ λ2 ≦). 670 [nm]), and an optical element that collects light beams having a plurality of wavelengths on an information recording medium,
A first optical element body disposed on the laser light source side of the optical pickup device;
A second optical element body disposed on the information recording medium side;
Provided on both surfaces of the first optical element body to form a first optical functional surface on the laser light source side and a second optical functional surface on the information recording medium side, and provided on both surfaces of the second optical element body An antireflection film formed with a third optical functional surface on the laser light source side and a fourth optical functional surface on the information recording medium side,
The first optical functional surface and the second optical functional surface are:
When the wavelength λ of the vertically incident light beam is λ = λ1 and λ = λ2, the reflectance is 1% or less,
When the wavelength λ is a certain wavelength within the range of λ1 <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The third optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1 [%] or less,
The fourth optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%].

According to the twenty-fifth aspect of the present invention, when the wavelength λ of the vertically incident light beam is λ = λ1, and when λ = λ2, the reflectance on the first and second optical function surfaces is 1 [ %] Or less, and the wavelength λ is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance at the third optical function surface is 1 [%] or less, and the wavelength λ is λ1 ≦ λ ≦ λ1 + 50. In the case of [nm] and in the case of λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance on the fourth optical function surface is 1 [%] or less. Can prevent reflection. Further, when the wavelength λ is a certain wavelength within the range of λ1 <λ <λ2, the reflectance at the first and second optical function surfaces shows a maximum value larger than 1 [%], and the wavelength λ is When the wavelength is within a range of λ1 + 50 [nm] <λ <λ2, the reflectance at the fourth optical function surface shows a maximum value larger than 1 [%], that is, the antireflection function is reduced. Unlike conventional antireflection films that prevent reflection of the entire light flux in a wide wavelength range of wavelengths λ1 to λ2, the layers of the antireflection film are not impaired without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. The number can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.
Even if the optical element body is made of optical plastic, the antireflection film may be cracked by the stress of the antireflection film, or the adhesion between the antireflection film and the optical element body may be reduced. Can be prevented, that is, environmental resistance can be improved.

The invention according to claim 26 is the optical element according to claim 25,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface and the second optical functional surface are:
When the wavelength λ is λ = λ3, the reflectance is 1% or less,
The third optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less,
The fourth optical functional surface is
When the wavelength λ is λ2 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less.

  According to a twenty-sixth aspect of the present invention, when the wavelength λ is λ = λ3, the reflectance at the first and second optical function surfaces is 1% or less, and the wavelength λ is λ1 ≦ λ ≦. When λ3 + 30 [nm], the reflectance at the third functional surface is 1% or less, and when the wavelength λ is λ2 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the fourth optical functional surface is Since the reflectance is 1 [%] or less, reflection can be prevented even for wavelengths in these bands.

The invention according to claim 27 is the optical element according to any one of claims 1 to 26,
It is an objective lens having a numerical aperture of 0.65 or more.

  According to the twenty-seventh aspect, since the objective lens has a numerical aperture of 0.65 or more, recording and / or reproduction can be performed using AOD as an information recording medium.

The invention according to claim 28 is the optical element according to any one of claims 1 to 27,
The antireflection film includes a low refractive index material having a refractive index n of 1.3 ≦ n ≦ 1.55 with respect to a light beam having a wavelength of 500 [nm];
It is formed from at least two kinds of materials among high refractive index materials satisfying 1.7 ≦ n ≦ 2.5.

  According to the invention of claim 28, the same effect as that of any one of claims 1 to 27 can be obtained.

The invention according to claim 29 is the optical element according to claim 28,
The low refractive index material is a material mainly composed of MgF ₂ or SiO ₂ ,
The high refractive index material is characterized by being a material mainly composed of TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZrO ₂ , HfO _2, or CeF ₃ .

  According to the twenty-ninth aspect, the same effect as that of the twenty-eighth aspect can be obtained.

The invention according to claim 30 is the optical element according to any one of claims 1 to 27,
The antireflection film includes a low refractive index material having a refractive index n of 1.3 ≦ n <1.55 with respect to a light beam having a wavelength of 500 [nm];
A medium refractive index material with 1.55 ≦ n <1.7;
It is formed of at least three kinds of materials among high refractive index materials satisfying 1.7 ≦ n <2.5.

  According to the invention of claim 30, the same effect as that of any one of claims 1 to 27 can be obtained.

The invention according to claim 31 is the optical element according to claim 30,
The low refractive index material is a material mainly composed of MgF ₂ or SiO ₂ ,
The medium refractive index material is a material mainly composed of Al ₂ O ₃ ,
The high refractive index material is characterized by being a material mainly composed of TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZrO ₂ , HfO _2, or CeF ₃ .

  According to the invention of claim 31, the same effect as that of the invention of claim 30 can be obtained.

Invention of Claim 32 in the optical element as described in any one of Claims 1-31,
The optical element body is made of plastic.

Here, as the plastic, optical plastics such as polycarbonate resin, polymethyl methacrylate resin, norbornene resin, and alicyclic olefin resin can be used. As the norbornene-based resin, a polyolefin-based resin is preferably used.
According to the invention of Claim 32, the same effect as that of any one of Claims 1 to 31 can be obtained.

Invention of Claim 33 in the optical element as described in any one of Claims 1-31,
The optical element body is made of glass.

Here, as the glass, a glass material for a low melting point glass mold can be used, and specifically, M-BaCD5 (trade name, manufactured by HOYA) or the like can be used.
According to the invention of Claim 33, the same effect as that of any one of Claims 1 to 31 can be obtained.

The invention according to claim 34 is the optical element according to any one of claims 1 to 33,
A base layer is interposed between the optical element body and the antireflection film,
The refractive index n ₀ ′ of the underlayer is characterized by | n ₀ ′ −n ₀ | ≦ 0.1, where n ₀ is the refractive index of the optical element body.

According to the thirty-fourth aspect, since the base layer is interposed between the optical element body and the antireflection film, the adhesion of the antireflection film to the optical element body can be improved.
Further, since the refractive index n ₀ ′ of the base layer satisfies | n ₀ ′ −n ₀ | ≦ 0.1 with respect to the refractive index n ₀ of the optical element body, the optical function is deteriorated by providing the base layer. Can be prevented.

The invention according to claim 35 is an optical pickup device,
The optical element according to any one of claims 1 to 34 and a laser light source,
At least one of recording information on the optical recording medium and reproducing information recorded on the optical recording medium by condensing the light beam emitted from the laser light source onto the optical recording medium by the optical element. One of them can be executed.

  According to the invention of Claim 35, the same effect as that of any one of Claims 1 to 34 can be obtained.

  According to the first aspect of the present invention, the number of antireflection films can be reduced without impairing the antireflection function for the light flux having the wavelength λ1 and the light flux having the wavelength 2. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.

  According to the second aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained, as well as the luminous flux of the use wavelength λ1 of the AOD or Blu-ray disc, the luminous flux of the use wavelength λ2 of the DVD, The reflection of the CD with the luminous flux having the wavelength λ3 can be prevented with an antireflection film having a small number of layers.

  According to the third aspect of the present invention, the same effect as that of the first or second aspect of the invention can be obtained, and a light flux of 0 [°] ≦ θmax ≦ 40 [°] Accurate recording and playback can be performed.

  According to the invention described in claims 4 to 6, the same effect as in the invention described in any one of claims 1 to 3 can be obtained, and the antireflection film can be obtained without impairing the antireflection function. The number of layers can be reduced.

  According to the invention described in claims 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, an antireflection film is obtained without impairing the antireflection function for the light flux of wavelength λ1 and the light flux of wavelength 2. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film can be suppressed.

  According to the invention described in claims 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, claims 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 are described. As a matter of course, the same effect as that of the present invention can be obtained, and reflection can also be prevented for a wavelength λ in a band near λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]).

  According to the twenty-seventh aspect of the invention, the same effects as those of the first to twenty-sixth aspects of the invention can be obtained, and recording and / or reproduction is performed using the AOD as an information recording medium. be able to.

According to the invention described in claims 28 and 30, the same effect as in the invention described in any one of claims 1 to 27 can be obtained.
According to the invention described in claims 29 and 31, the same effect as in the invention described in claims 28 and 30 can be obtained.
According to invention of Claim 32,33, the effect similar to the invention as described in any one of Claims 1-31 can be acquired.

  According to the thirty-fourth aspect of the invention, it is possible to obtain the same effect as the invention according to any one of the first to thirty-third aspects. Therefore, the adhesion of the antireflection film to the optical element body can be improved.

  According to the invention of Claim 35, the same effect as that of any one of Claims 1 to 34 can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
First, an embodiment of an optical pickup device according to the present invention will be described.
FIG. 1 is a schematic configuration diagram of an optical pickup device 1 according to the first embodiment.
As shown in this figure, the optical pickup device 1 includes a first light source 2a and a second light source 2b that emit laser light.

The first light source 2a emits a first light flux having a wavelength λ1, and the wavelength λ1 is 380 [nm] ≦ λ1 ≦ 450 [nm], and in this embodiment, λ1 = 405 [nm]. The wavelength λ1 is a wavelength used for the AOD (information recording medium) 100. The thickness t1 of the protective substrate 101 of the AOD 100 is 0.5 [mm] ≦ t1 ≦ 0.7 [mm].
The second light source 2b emits a second light flux having a wavelength λ2. The wavelength λ2 is 640 [nm] ≦ λ2 ≦ 680 [nm], and in this embodiment, λ2 = 650 [nm]. This wavelength λ2 is a wavelength used for the DVD (information recording medium) 200. The thickness t2 of the protective substrate 201 of the DVD 200 is 0.5 [mm] ≦ t2 ≦ 0.7 [mm].

The light beams emitted from the first light source 2a and the second light source 2b are condensed on the AOD 100 and the DVD 200 by the condensing optical system 3.
The condensing optical system 3 includes first and second collimating lenses 30 a and 30 b, first to third beam splitters 31 a to 31 c, and an objective lens (optical element) 5.
The first and second collimating lenses 30a and 30b are configured so that light beams emitted from the first and second light sources 2a and 2b are parallel light.

The beam splitter 31a transmits the first light beam emitted from the first light source 2a in the direction of the objective lens 5, and guides reflected light from the AOD 100, that is, return light, to the first photodetector 4a. . A sensor lens group 33a is disposed between the beam splitter 31a and the first photodetector 4a.
The beam splitter 31b transmits the second light beam emitted from the second light source 2b in the direction of the beam splitter 31c, and guides the reflected light from the DVD 200 to the second photodetector 4b. A sensor lens group 33b is disposed between the beam splitter 31b and the second photodetector 4b.
The beam splitter 31c places the first light beam from the first light source 2a and the second light beam from the second light source 2b on the same optical path.

  As shown in FIG. 2, the objective lens 5 includes a lens body (optical element body) 50 and an antireflection film 51, and is mounted on a two-dimensional actuator (not shown) that can move in a predetermined direction. The numerical aperture NA of the objective lens 5 is 0.65, and the maximum incident / exit angle θmax of the light beam having the wavelength λ1 on the optical function surfaces 52 and 53 is 0 [°] ≦ θmax ≦ 40 [°].

The lens body 50 is made of plastic or glass and has a refractive index n ₀ of 1.45 ≦ n ₀ ≦ 1.65.
Here, as the plastic used for the lens body 50, optical plastics such as polycarbonate resin, polymethyl methacrylate resin, norbornene resin, and alicyclic olefin resin can be used. As the norbornene-based resin, a polyolefin-based resin is preferably used. Moreover, as glass used for the lens body 50, a glass material for low melting glass mold can be used, and specifically, M-BaCD5 (trade name, manufactured by HOYA) or the like can be used.

The antireflection film 51 is provided on at least one surface of the lens main body 50, in this embodiment, both surfaces, and forms optical function surfaces 52 and 53. The reflectance of the light beam perpendicularly incident on the optical functional surfaces 52 and 53 shows a maximum value of 1% or more between the wavelengths λ1 and λ2, and is relatively low at the wavelengths λ1 and λ2. . Therefore, the first light flux and the second light flux are prevented from being reflected by the optical function surfaces 52 and 53.
The antireflection film 51 includes a low refractive index material having a refractive index n of 1.3 ≦ n ≦ 1.55 with respect to a light beam having a wavelength of 500 [nm], and
Of the high refractive index material satisfying 1.7 ≦ n ≦ 2.5, it is composed of at least two layers and not less than 30 layers. Here, as the low refractive index material, a material mainly composed of MgF ₂ or SiO ₂ can be used. As the high refractive index material, a material mainly composed of TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZrO ₂ , HfO ₂ or CeF ₃ can be used. Further, for the formation of the antireflection film 51, methods such as vapor deposition, sputtering, CVD, and coating are used.

Further, the layers included in the anti-reflection film 51, a first layer from the side close to the lens body 50 in this order, the second layer, ... When the n-th layer, the refractive index n ₁ and the optical film thickness nd ₁ of the first layer The refractive index n ₂ and the optical film thickness nd _{2 of} the second layer are
1.7 ≦ n ₁ ≦ 2.5, 225 [nm] ≦ nd ₁ ≦ 275 [nm]
1.3 ≦ n ₂ ≦ 1.55, 100 [nm] ≦ nd ₂ ≦ 150 [nm]
It has become.

In addition, it is preferable to interpose a base layer (not shown) between the lens body 50 and the antireflection film 51. In this case, the adhesion of the antireflection film 51 to the lens body 50 can be improved. Further, the refractive index n ₀ ′ of the underlayer is preferably | n ₀ ′ −n ₀ | ≦ 0.1 with respect to the refractive index n ₀ of the lens body 50. In this case, the optical function is prevented from being deteriorated by providing the base layer.

  Since the operation of the optical pickup device 1 configured as described above is well known and will not be described in detail, the first light beam emitted from the first light source 2a passes through the first beam splitter 31a, The light is collimated by one collimating lens 30a and passes through the third beam splitter 31c.

Next, the first light beam is condensed on the information recording surface of the AOD 100 by the objective lens 5 to form a spot on the optical axis L. The first light flux that forms the spot is modulated and reflected by the information pits on the information recording surface, and passes through the objective lens 5 again. Here, since the reflection of the first light beam on the optical function surfaces 52 and 53 is prevented by the antireflection film 51, the first light beam passes through the objective lens 5 without reducing the light amount.
Next, the first light beam passes through the third beam splitter 31c and the first collimating lens 30a, is reflected by the first beam splitter 31a, and is branched.
And the branched 1st light beam injects into the 1st photodetector 4a through the sensor lens group 33a. The first photodetector 4a detects a spot of incident light and outputs a signal, and obtains a read signal of information recorded in the AOD 100 using the output signal.

  In addition, focus detection and track detection are performed by detecting a change in the amount of light due to a change in the shape of the spot or a change in position on the first photodetector 4a. Based on the detection result, the two-dimensional actuator moves the objective lens 5 in the focus direction and the tracking direction so that the first light beam accurately forms a spot on the information recording surface.

  On the other hand, after passing through the second beam splitter 31b, the second light beam emitted from the second light source 2b is collimated by the second collimating lens 30b, reflected by the third beam splitter 31c, and reaches the objective lens 5. .

Next, the second light beam is condensed on the information recording surface of the DVD 200 by the objective lens 5 to form a spot on the optical axis L. The second light flux that forms the spot is modulated and reflected by the information pits on the information recording surface, and passes through the objective lens 5 again. Here, since the reflection of the second light flux on the optical function surfaces 52 and 53 is prevented by the antireflection film 51, the second light flux passes through the objective lens 5 without reducing the amount of light.
Next, the second light beam is reflected by the third beam splitter 31c and branched.
The branched second light beam passes through the second collimating lens 30b, is reflected and branched by the second beam splitter 31b, and enters the second photodetector 4b through the sensor lens group 33a. The following is the same as in the case of the first light flux.

According to the optical pickup device 1 as described above, unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of wavelengths λ1 to λ2, the antireflection function for the first light flux and the second light flux is provided. The number of antireflection films 51 can be reduced without loss. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51 can be suppressed.
Further, even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51 due to the stress of the antireflection film 51, or the adhesion between the antireflection film 51 and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

In the above embodiment, the wavelength of the second light source has been described as being 640 [nm] or more and 680 [nm] or less, but may be 750 [nm] or more and 850 [nm] or less. In this case, a CD can be used instead of the DVD 200 as the information recording medium.

<Second Embodiment>
Next, a second embodiment of the optical pickup device according to the present invention will be described. In addition, the same code | symbol is attached | subjected to the component similar to the said 1st Embodiment, and the description is abbreviate | omitted.

  Unlike the first optical pickup device 1, the optical pickup device 1 </ b> A according to the second embodiment includes an objective lens 5 </ b> A instead of the objective lens 5.

As shown in FIG. 2, the objective lens 5A includes a lens body 50 and an antireflection film 51A.
The antireflection film 51A is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52A and 53A. The reflectivity of the light beam perpendicularly incident on the optical functional surfaces 52A and 53A exhibits a maximum value of 1% or more between the wavelengths λ1 and λ2, and is relatively low at the wavelengths λ1 and λ2. . Accordingly, the first light flux and the second light flux are prevented from being reflected by the optical functional surfaces 52A and 53A.
The antireflection film 51A includes a low refractive index material having a refractive index n of 1.3 ≦ n <1.55 with respect to a light beam having a wavelength of 500 [nm], and
A medium refractive index material with 1.55 ≦ n <1.7;
Of the high refractive index material satisfying 1.7 ≦ n <2.5, it is formed of at least three kinds of materials and not less than three layers and not more than 30 layers. Here, as the low refractive index material, a material mainly composed of MgF ₂ or SiO ₂ can be used. Further, as the medium refractive index material, a material mainly composed of Al ₂ O ₃ can be used. As the high refractive index material, a material mainly composed of TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZrO ₂ , HfO ₂ or CeF ₃ can be used.

Among the layers included in the antireflection film 51A, the refractive index n ₁ and film thickness nd ₁ of the first layer, the refractive index n ₂ and film thickness nd ₂ of the second layer, and the refractive index n of the third layer. ₃ and film thickness nd ₃ are
1.7 ≦ n ₁ ≦ 2.5, 125 [nm] ≦ nd ₁ ≦ 175 [nm],
1.55 ≦ n ₂ <1.7, 75 [nm] ≦ nd ₂ ≦ 125 [nm],
1.3 ≦ n ₃ <1.55, 100 [nm] ≦ nd ₃ ≦ 150 [nm],
It has become.

The operation of the optical pickup device 1A as described above is the same as the operation of the optical pickup device 1 in the first embodiment.
Also with this optical pickup device 1A, the same effect as in the first embodiment can be obtained.

<Third Embodiment>
Next, a third embodiment of the optical pickup device according to the present invention will be described. In addition, the same code | symbol is attached | subjected to the component similar to the said 1st Embodiment, and the description is abbreviate | omitted.

FIG. 3 is a schematic configuration diagram of an optical pickup device 1B according to the second embodiment.
As shown in this figure, the optical pickup device 1B is different from the optical pickup device 1 in the first embodiment, and further includes a third light source 2c, a collimator lens 30c, a beam splitter 31d, and a diffraction plate 6, and Instead of the objective lens 5, an objective lens 5B is provided.

The third light source 2c emits a third light flux having a wavelength λ3, and the wavelength λ3 is 750 [nm] ≦ λ3 ≦ 850 [nm], and in this embodiment, λ3 = 780 [nm]. The wavelength λ3 is a use wavelength for the CD (third optical information recording medium) 300. The thickness t3 of the protective substrate 301 of the CD 300 is 1.1 [mm] ≦ t3 ≦ 1.3 [mm].
The third collimating lens 30c converts the light beam emitted from the third light source 2c into parallel light.
The beam splitter 31d places the third light flux from the third light source 2c and the first light flux and the second light flux transmitted through the beam splitter 31c on the same optical path. A diffractive plate 6 is disposed between the beam splitter 31d and the third light source 2c to guide the reflected light from the CD 300 to the third photodetector 4c.

As shown in FIG. 2, the objective lens 5B includes a lens body (optical element body) 50B and an antireflection film 51B having an antireflection function for the first light beam, the second light beam, and the third light beam. .
The antireflection film 51B is provided on at least one surface of the lens main body 50, in this embodiment, both surfaces, and forms optical function surfaces 52B and 53B. The reflectance of the light beam perpendicularly incident on the optical functional surfaces 52B and 53B exhibits a maximum value of 1% or more between the wavelengths λ1 and λ2, and is relatively low at the wavelengths λ1 and λ2. . Accordingly, the first light flux and the second light flux are prevented from being reflected by the optical function surfaces 52B and 53B.
The antireflection film 51B includes a low refractive index material having a refractive index n of 1.3 ≦ n ≦ 1.55 for a light beam having a wavelength of 500 [nm], and
Among the high refractive index materials satisfying 1.7 ≦ n ≦ 2.5, the layers are formed of at least two types of materials and not less than 4 layers and not more than 30 layers.

Of the layers included in the antireflection film 51B, the refractive index n ₁ and the optical film thickness nd ₁ of the first layer, the refractive index n ₂ and the optical film thickness nd ₂ of the second layer, and the refraction of the third layer. a rate n ₃ and the optical thickness nd _3, the refractive index n ₄ and the optical thickness nd ₄ of the fourth layer,
1.7 ≦ n ₁ ≦ 2.5, 25 [nm] ≦ nd ₁ ≦ 75 [nm],
1.3 ≦ n ₂ ≦ 1.55, 25 [nm] ≦ nd ₂ ≦ 75 [nm],
1.7 ≦ n ₃ ≦ 2.5, 225 [nm] ≦ nd ₃ ≦ 275 [nm],
1.3 ≦ n ₄ ≦ 1.55, 135 [nm] ≦ nd ₄ ≦ 185 [nm]
It has become.

Of the operations of the optical pickup apparatus 1B configured as described above, recording and / or reproduction using the AOD 100 and the DVD 200 is the same as that of the optical pickup apparatus 1 in the first embodiment.
In the recording and / or reproduction using the CD 300 in the operation of the optical pickup device 1B, first, the third light beam emitted from the third light source 2c passes through the diffraction plate 6 and then the third collimating lens. The light is collimated at 30 c, reflected by the fourth beam splitter 31 d, and reaches the objective lens 5.

Next, the third light beam is condensed on the information recording surface of the CD 300 by the objective lens 5 to form a spot on the optical axis L. The third light flux that forms the spot is modulated and reflected by the information pits on the information recording surface, and passes through the objective lens 5 again. Here, since the reflection of the second light beam on the optical function surfaces 52 and 53 is prevented by the antireflection film 51, the third light beam passes through the objective lens 5 without reducing the amount of light.
Next, the third light flux is reflected by the fourth beam splitter 31d and branched.
Then, the branched third light beam passes through the third collimating lens 30c, changes its path when passing through the diffraction plate 6, and enters the third photodetector 4c. The following is the same as in the case of the first light flux.

According to the optical pickup device 1B as described above, unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of wavelengths λ1 to λ3, the first light flux, the second light flux, and the third light flux. The number of antireflection films 51B can be reduced without impairing the antireflection function. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51B can be suppressed.
Even when the lens body 50 is made of an optical plastic, a crack occurs in the antireflection film 51B due to the stress of the antireflection film 51B, or the adhesion between the antireflection film 51B and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Fourth embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> C according to the fourth embodiment includes an objective lens 5 </ b> C instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5C includes a lens body 50 and an antireflection film 51C.

The antireflection film 51C is provided on at least one surface of the lens main body 50, in this embodiment, both surfaces, and forms optical functional surfaces 52C and 53C. More specifically, the antireflection film 51C has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed so as to be as follows. That is, the thickness of the antireflection film 5C is substantially uniform.
The optical function surfaces 52C and 53C have a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°]. Further, the optical function surfaces 52C and 53C have reflectivity when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm]. 1 [%] or less. Further, the optical functional surfaces 52C and 53C exhibit a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1C described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1C, the wavelength λ of the light beam perpendicularly incident on the optical functional surfaces 52C and 53C is λ1 ≦ λ ≦ λ1 + 15 [nm], and the case where λ2 ≦ λ ≦ λ2 + 15 [nm]. Since the reflectance at the optical functional surfaces 52C and 53C is 1% or less, reflection can be prevented for wavelengths within these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in a wide wavelength range of λ1 to λ2, the number of layers of the antireflection film 51C is reduced without impairing the antireflection function for the first light flux and the second light flux. Can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51C can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51C due to the stress of the antireflection film 51C, or the adhesion between the antireflection film 51C and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Fifth embodiment>
Unlike the first optical pickup apparatus 1, the optical pickup apparatus 1 </ b> D in the fifth embodiment includes an objective lens 5 </ b> D instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5D includes a lens body 50 and an antireflection film 51D.

The antireflection film 51D is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52D and 53D. More specifically, the antireflection film 51D has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed so as to be as follows. That is, the thickness of the antireflection film 5D is substantially uniform.
The optical function surfaces 52D and 53D have a maximum incident / exit angle θmax within the effective diameter of 40 [°] <θmax <90 [°]. Further, the optical function surfaces 52D and 53D have reflectivity when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. 1 [%] or less. Further, the optical functional surfaces 52D and 53D exhibit a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1D described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1D, the wavelength λ of the light beam perpendicularly incident on the optical function surfaces 52D and 53D is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ λ ≦ λ2 + 40 [nm]. Since the reflectance at the optical functional surfaces 52D and 53D is 1% or less, reflection can be prevented for wavelengths within these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike a conventional antireflection film that prevents reflection of the entire light flux in a wide wavelength range of λ1 to λ2, the number of layers of the antireflection film 51D is reduced without impairing the antireflection function for the first light flux and the second light flux. Can be reduced. Therefore, it is possible to reduce the production cost and to suppress the change in spectral characteristics due to the permeation of moisture between the layers of the antireflection film 51D.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51D due to the stress of the antireflection film 51D, or the adhesion between the antireflection film 51D and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Sixth Embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> E according to the sixth embodiment includes an objective lens 5 </ b> E instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5E includes a lens body 50 and an antireflection film 51E.

The antireflection film 51E is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52E and 53E. More specifically, the antireflection film 51E has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed so as to be as follows. That is, the thickness of the antireflection film 5E is substantially uniform.
The optical function surface 52E has a maximum incident / exit angle θmax within the effective diameter of 40 [°] <θmax <90 [°]. The optical function surface 52E has a reflectance of 1 [1] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. %] Or less. Further, the optical functional surface 52E exhibits a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.
The optical function surface 53E has a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°]. The optical function surface 53E has a reflectance of 1 [1] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm]. %] Or less. The optical function surface 53E exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1E is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1E, when the wavelength λ of the light beam perpendicularly incident on the optical function surface 53E is λ1 ≦ λ ≦ λ1 + 15 [nm], and when λ2 ≦ λ ≦ λ2 + 15 [nm]. The reflectance at the optical functional surface 53E is 1% or less, and the wavelength λ of the light beam incident perpendicularly to the optical functional surface 52E is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ λ ≦ λ2 + 40 [ In the case of [nm], since the reflectance at the optical functional surface 52E is 1% or less, reflection can be prevented for wavelengths within these bands. Further, the optical functional surface 53E exhibits a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, and the optical functional surface 52E. In the case where the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents the reflection of the entire light beam in the wide wavelength range of λ1 to λ2, the number of layers of the antireflection film 51E is reduced without impairing the antireflection function for the first light beam and the second light beam. Can be reduced. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51E can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51E due to the stress of the antireflection film 51E, or the adhesion between the antireflection film 51E and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In the present embodiment, the optical function surface 52E is described as a light incident surface, and the optical function surface 53E is described as a light output surface. However, the optical function surface 52E may be a light output surface and the optical function surface 53E may be a light output surface. good.

<Seventh embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1F according to the seventh embodiment includes an objective lens 5F instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5F includes a lens body 50 and an antireflection film 51F.

The antireflection film 51F is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52F and 53F. More specifically, the antireflection film 51F has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the thickness of the antireflection film 5F is not uniform.
In the optical function surfaces 52F and 53F, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [ °] ≦ θ⊥max ≦ 40 [°]. Further, the optical function surfaces 52F and 53F have reflectivity when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm]. 1 [%] or less. Further, the optical functional surfaces 52F and 53F exhibit a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1F described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1F, the wavelength λ of the light beam perpendicularly incident on the optical function surfaces 52F and 53F is λ1 ≦ λ ≦ λ1 + 15 [nm] and the case where λ2 ≦ λ ≦ λ2 + 15 [nm]. Since the reflectance at the optical functional surfaces 52F and 53F is 1% or less, reflection can be prevented for wavelengths in these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in the wide wavelength range of λ1 to λ2, the number of layers of the antireflection film 51F is reduced without impairing the antireflection function for the first light flux and the second light flux. Can be reduced. Therefore, it is possible to reduce the production cost and to suppress the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51F.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51F due to the stress of the antireflection film 51F, or the adhesion between the antireflection film 51F and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Eighth Embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1G according to the eighth embodiment includes an objective lens 5G instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5G includes a lens body 50 and an antireflection film 51G.

The antireflection film 51G is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52G and 53G. More specifically, the antireflection film 51G has a {(maximum film thickness within the effective diameter for the first light flux) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the thickness of the antireflection film 5G is not uniform.
The optical function surfaces 52G and 53G have a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°] and 40 [ °] <θ⊥max <90 [°]
Alternatively, 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. The optical function surfaces 52G and 53G have a reflectance when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. 1 [%] or less. Further, the optical functional surfaces 52G and 53G exhibit a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1G described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1G, the wavelength λ of the light beam perpendicularly incident on the optical function surfaces 52G and 53G is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ λ ≦ λ2 + 40 [nm]. Since the reflectance at the optical functional surfaces 52G and 53G is 1% or less, reflection can be prevented for wavelengths within these bands. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in a wide wavelength range of λ1 to λ2, the number of layers of the antireflection film 51G is reduced without impairing the antireflection function for the first light flux and the second light flux. Can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51G can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51G due to the stress of the antireflection film 51G, or the adhesion between the antireflection film 51G and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Ninth embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> I according to the ninth embodiment includes an objective lens 5 </ b> I instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5I includes a lens body 50 and an antireflection film 51I.

The antireflection film 51I is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52I and 53I. More specifically, the antireflection film 51I has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the film thickness of the antireflection film 5I is not uniform.
The optical functional surface 52I has a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] < θ⊥max <90 [°]
Alternatively, 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. The optical function surface 52I has a reflectance of 1 [1] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. %] Or less. Further, the optical functional surface 52I exhibits a maximum value with a reflectance higher than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.
In the optical function surface 53I, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. The optical function surface 53I has a reflectance of 1 [1] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm]. %] Or less. Further, the optical functional surface 53I exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1I described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1I, when the wavelength λ of the light beam perpendicularly incident on the optical function surface 53I is λ1 ≦ λ ≦ λ1 + 15 [nm], and when λ2 ≦ λ ≦ λ2 + 15 [nm]. The reflectance at the optical functional surface 53I is 1% or less, and the wavelength λ of the light beam incident perpendicularly to the optical functional surface 52I is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ λ ≦ λ2 + 40 [ In the case of [nm], since the reflectance at the optical functional surface 52I is 1% or less, reflection can be prevented for wavelengths in these bands. Further, the optical function surface 53I shows a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, and the optical function surface 52I. In the case where the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in the wide wavelength range of λ1 to λ2, the number of layers of the antireflection film 51I is reduced without impairing the antireflection function for the first light flux and the second light flux. Can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51I can be suppressed.
Even when the lens body 50 is made of an optical plastic, a crack occurs in the antireflection film 51I due to the stress of the antireflection film 51I, or the adhesion between the antireflection film 51I and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In the present embodiment, the optical function surface 52I is described as a light incident surface and the optical function surface 53I is defined as a light output surface. However, the optical function surface 52I may be a light output surface and the optical function surface 53I may be a light output surface. good.

<Tenth Embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> J according to the tenth embodiment includes an objective lens 5 </ b> J instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5J includes a lens body 50 and an antireflection film 51J.

The antireflection film 51J is provided on at least one surface of the lens main body 50, in this embodiment, both surfaces, and forms optical function surfaces 52J and 53J. More specifically, the antireflection film 51J has a {(maximum film thickness within the effective diameter for the first light flux) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the thickness of the antireflection film 5J is nonuniform.
The optical function surface 52J has a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 40 [°] <θmax <90 [°] and 40 [°]. <Θ⊥max <90 [°]. Further, the optical function surface 52J is configured to suppress the reflectance to 1.5 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ2 + 130 [nm].
In the optical function surface 53J, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°]. ≦ θ⊥max ≦ 40 [°]. The optical function surface 53J has a reflectance of 1 [1] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm]. %] Or less. Further, the optical functional surface 53J exhibits a maximum value with a reflectance higher than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1J is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1J, when the wavelength λ of the light beam perpendicularly incident on the optical function surface 53J is λ1 ≦ λ ≦ λ1 + 15 [nm], and when λ2 ≦ λ ≦ λ2 + 15 [nm]. When the reflectance at the optical function surface 53J is 1% or less and the wavelength λ of the light beam perpendicularly incident on the optical function surface 52J is λ1 ≦ λ ≦ λ2 + 130 [nm], Since the reflectance is 1.5 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the optical function surface 53J, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. In contrast, the number of antireflection films 51J can be reduced without impairing the antireflection function for the first light flux and the second light flux. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51J can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film J due to the stress of the antireflection film 51J, or the adhesion between the antireflection film 51J and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In this embodiment, the optical function surface 52J is described as a light incident surface, and the optical function surface 53J is described as a light output surface. However, the optical function surface 52J may be a light output surface and the optical function surface 53J may be a light output surface. good.

<Eleventh embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> K according to the eleventh embodiment includes an objective lens 5 </ b> K instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5K includes a lens body 50 and an antireflection film 51K.

The antireflection film 51K is provided on at least one surface of the lens body 50, that is, both surfaces in the present embodiment, and forms optical function surfaces 52K and 53K. More specifically, the antireflection film 51K has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the thickness of the antireflection film 5K is not uniform.
The optical function surface 52K has a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 40 [°] <θmax <90 [°] and 40 [°] < θ⊥max <90 [°]. The optical function surface 52K is configured to suppress the reflectance to 1.5 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ2 + 130 [nm].
In the optical function surface 53K, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] < θ⊥max <90 [°]
Alternatively, 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. The optical function surface 53K has a reflectance of 1 [1] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. %] Or less. Further, the optical functional surface 53K exhibits a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1K described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1K, when the wavelength λ of the light beam perpendicularly incident on the optical function surface 53K is λ1 ≦ λ ≦ λ1 + 50 [nm], and when λ2 ≦ λ ≦ λ2 + 40 [nm]. When the reflectance at the optical functional surface 53K is 1% or less and the wavelength λ of the light beam perpendicularly incident on the optical functional surface 52K is λ1 ≦ λ ≦ λ2 + 130 [nm], the optical functional surface 52K Since the reflectance is 1.5 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the optical function surface 53K, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. In contrast, the number of antireflection films 51K can be reduced without impairing the antireflection function for the first light flux and the second light flux. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51K can be suppressed.
Even when the lens body 50 is made of an optical plastic, a crack occurs in the antireflection film K due to the stress of the antireflection film 51K, or the adhesion between the antireflection film 51K and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In this embodiment, the optical function surface 52K is described as a light incident surface, and the optical function surface 53K is described as a light output surface. However, the optical function surface 52K may be used as a light output surface and the optical function surface 53K may be used as a light output surface. good.

<Twelfth embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> L according to the twelfth embodiment includes an objective lens 5 </ b> L instead of the objective lens 5.
As shown in FIG. 2, the objective lens 5L includes a lens body 50 and an antireflection film 51L.

The antireflection films 51L are provided on both surfaces of the lens body 50, and form optical function surfaces 52L and 53L.
The optical function surface 52L suppresses the reflectance to 1 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ2 + 40 [nm].
The optical function surface 53L has a reflectance of 1 [%] when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. It is designed to keep it below. In addition, the optical functional surface 53L exhibits a maximum value with a reflectance greater than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1L described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1L, when the wavelength λ of the light beam perpendicularly incident on the optical function surface 52L is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance at the optical function surface 52L is 1 [%] or less. In the case where the wavelength λ of the light beam perpendicularly incident on the optical function surface 53L is λ1 ≦ λ ≦ λ1 + 50 [nm] and in the case where λ2 ≦ λ ≦ λ2 + 40 [nm], the optical function surface 53L Since the reflectance is 1 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the optical function surface 53L, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, antireflection. Since the function is lowered, the number of layers of the antireflection film 51L can be reduced without impairing the antireflection function for the first light flux and the second light flux unlike the conventional case. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51L can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51L due to the stress of the antireflection film 51L, or the adhesion between the antireflection film 51L and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In the present embodiment, the optical function surface 52L is described as a light incident surface, and the optical function surface 53L is described as a light output surface. However, the optical function surface 52L may be a light output surface and the optical function surface 53L may be a light output surface. good.

<Thirteenth embodiment>
Unlike the first optical pickup device 1, the optical pickup device 1 </ b> M according to the thirteenth embodiment includes an objective lens 5 </ b> M instead of the objective lens 5.
As shown in FIG. 4, the objective lens 5M includes two lens bodies 501, 502 and an antireflection film 51M.
The lens body 501 is disposed on the laser light sources 2a and 2b side, and the lens body 502 is disposed on the information recording medium side such as AOD100.

The antireflection film 51M is provided on both surfaces of the lens bodies 501 and 502, and forms optical function surfaces 54 to 57.
The optical function surface 54 on the laser light sources 2a and 2b side and the optical function surface 55 on the information recording medium side with respect to the lens body 501 have a case where the wavelength λ of the vertically incident light beam is λ = λ1, and λ = λ2. In this case, the reflectance is suppressed to 1% or less.
The optical function surface 56 on the laser light sources 2a and 2b side with respect to the lens main body 502 has a reflectance of 1 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ2 + 40 [nm]. It is supposed to suppress.
The optical function surface 57 on the information recording medium side with respect to the lens body 502 has a case where the wavelength λ of the light beam perpendicularly incident is λ1 ≦ λ ≦ λ1 + 50 [nm] and a case where λ2 ≦ λ ≦ λ2 + 40 [nm]. The reflectance is suppressed to 1 [%] or less. The optical function surface 57 exhibits a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1M described above is the same as that of the optical pickup device 1 in the first embodiment.
According to the optical pickup device 1M, when the wavelength λ of the light beam perpendicularly incident on the optical function surfaces 54 and 55 is λ = λ1, and when λ = λ2, the optical function surfaces 54 and 55 When the reflectance is 1 [%] or less and the wavelength λ of the light beam perpendicularly incident on the optical function surface 56 is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance at the optical function surface 56 is 1 [%]. The optical function surface is obtained when the wavelength λ of the light beam perpendicularly incident on the optical function surface 57 is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm]. Since the reflectance at 57 is 1 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the optical function surface 57, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, antireflection. Since the function is lowered, the number of layers of the antireflection film 51M can be reduced without impairing the antireflection function for the first light flux and the second light flux unlike the conventional case. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51M can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51M due to the stress of the antireflection film 51M, or the adhesion between the antireflection film 51M and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Fourteenth embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1N according to the fourteenth embodiment includes an objective lens 5N instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5N includes a lens body 50 and an antireflection film 51N.

The antireflection film 51N is provided on at least one surface of the lens main body 50, in this embodiment, both surfaces, and forms optical function surfaces 52N and 53N. More specifically, the antireflection film 51N has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed so as to be as follows. That is, the thickness of the antireflection film 5N is substantially uniform.
The optical function surfaces 52N and 53N have a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°]. The optical functional surfaces 52N and 53N have a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 ≦ λ ≦ λ3 + 15. In the case of [nm], the reflectance is suppressed to 1 [%] or less. Further, the optical functional surfaces 52N and 53N exhibit a maximum value having a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1N described above is the same as that of the optical pickup device 1B in the third embodiment.
According to this optical pickup device 1N, the case where the wavelength λ of the light beam perpendicularly incident on the optical functional surfaces 52N and 53N is λ1 ≦ λ ≦ λ1 + 15 [nm] and the case where λ2 ≦ λ ≦ λ2 + 15 [nm] are satisfied. In the case of λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectivity at the optical functional surfaces 52N and 53N is 1% or less, and therefore reflection is prevented for wavelengths within these bands. Can do. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of λ1 to λ3, the antireflection film 51N does not impair the antireflection function for the first light flux, the second light flux, and the third light flux. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51N can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51N due to the stress of the antireflection film 51N, or the adhesion between the antireflection film 51N and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Fifteenth embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1O according to the fifteenth embodiment includes an objective lens 5O instead of the objective lens 5B.
The objective lens 5O includes a lens body 50 and an antireflection film 51O, as shown in FIG.

The antireflection film 51O is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52O and 53O. More specifically, the antireflection film 51O has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed so as to be as follows. That is, the thickness of the antireflection film 5O is substantially uniform.
The optical function surfaces 52O and 53O have a maximum incident / exit angle θmax within the effective diameter of 40 [°] <θmax <90 [°]. The optical function surfaces 52O and 53O have a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm], λ2 ≦ λ ≦ λ2 + 40 [nm], and λ3 ≦ λ ≦ λ3 + 30. In the case of [nm], the reflectance is suppressed to 1 [%] or less. Further, the optical functional surfaces 52O and 53O exhibit a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1O is the same as that of the optical pickup device 1B in the third embodiment.
According to this optical pickup device 1O, the case where the wavelength λ of the light beam perpendicularly incident on the optical function surfaces 52O and 53O is λ1 ≦ λ ≦ λ1 + 50 [nm] and the case where λ2 ≦ λ ≦ λ2 + 40 [nm] are satisfied. In the case of λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the optical functional surfaces 52O and 53O is 1% or less, and therefore, reflection is prevented for wavelengths within these bands. Can do. Further, when the wavelength λ is a certain wavelength in the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in the wide wavelength range of λ1 to λ3, the antireflection film 51O is obtained without impairing the antireflection function for the first light flux, the second light flux, and the third light flux. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51O can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51O due to the stress of the antireflection film 51O, or the adhesion between the antireflection film 51O and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Sixteenth Embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1P according to the sixteenth embodiment includes an objective lens 5P instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5P includes a lens body 50 and an antireflection film 51P.

The antireflection film 51P is provided on at least one surface of the lens body 50, that is, both surfaces in the present embodiment, and forms optical function surfaces 52P and 53P. More specifically, the antireflection film 51P has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5 [%]. The film is formed so as to be as follows. That is, the thickness of the antireflection film 5P is substantially uniform.
The optical function surface 52P has a maximum incident / exit angle θmax within the effective diameter of 40 [°] <θmax <90 [°]. The optical function surface 52P has a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm], λ2 ≦ λ ≦ λ2 + 40 [nm], and λ3 ≦ λ ≦ λ3 + 30 [nm]. ], The reflectance is suppressed to 1% or less. The optical function surface 52P exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.
The optical function surface 53P has a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°]. The optical function surface 53P has a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 ≦ λ ≦ λ3 + 15 [nm]. ], The reflectance is suppressed to 1% or less. In addition, the optical functional surface 53P exhibits a maximum value with a reflectance higher than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1P described above is the same as that of the optical pickup device 1B in the third embodiment.
According to this optical pickup device 1P, the wavelength λ of the light beam perpendicularly incident on the optical function surface 53P is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 In the case of ≦ λ ≦ λ3 + 15 [nm], the reflectance at the optical function surface 53P is 1% or less, and the wavelength λ of the light beam perpendicularly incident on the optical function surface 52P is λ1 ≦ λ ≦ λ1 + 50 [nm]. , Λ2 ≦ λ ≦ λ2 + 40 [nm], and λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the optical function surface 52P is 1% or less. Reflection can be prevented for wavelengths within these bands. Further, the optical function surface 53P shows a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, and the optical function surface 52P In the case where the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in the wide wavelength range of λ1 to λ3, the antireflection film 51P is provided without impairing the antireflection function for the first light flux, the second light flux, and the third light flux. The number of layers can be reduced. Therefore, it is possible to reduce the production cost and to suppress the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51P.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51P due to the stress of the antireflection film 51P, or the adhesion between the antireflection film 51P and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In the present embodiment, the optical function surface 52P is described as a light incident surface, and the optical function surface 53P is described as a light output surface. However, the optical function surface 52P may be a light output surface and the optical function surface 53P may be a light output surface. good.

<Seventeenth embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1Q according to the seventeenth embodiment includes an objective lens 5Q instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5Q includes a lens body 50 and an antireflection film 51Q.

The antireflection film 51Q is provided on at least one surface of the lens body 50, or both surfaces in the present embodiment, and forms optical function surfaces 52Q and 53Q. More specifically, the antireflection film 51Q has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5 [%]. The film is formed to be larger. That is, the thickness of the antireflection film 5Q is not uniform.
In the optical function surfaces 52Q and 53Q, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [ °] ≦ θ⊥max ≦ 40 [°]. The optical function surfaces 52Q and 53Q have a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 ≦ λ ≦ λ3 + 15. In the case of [nm], the reflectance is suppressed to 1 [%] or less. In addition, the optical functional surfaces 52Q and 53Q exhibit a maximum value with a reflectance higher than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1Q described above is the same as that of the optical pickup device 1B in the third embodiment.
According to the optical pickup device 1Q, the wavelength λ of the light beam perpendicularly incident on the optical function surfaces 52Q and 53Q is λ1 ≦ λ ≦ λ1 + 15 [nm], and the case where λ2 ≦ λ ≦ λ2 + 15 [nm]. In the case of λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance at the optical functional surfaces 52Q and 53Q is 1% or less. Can do. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in the wide wavelength range of λ1 to λ3, the antireflection film 51Q is not impaired without impairing the antireflection function for the first light flux, the second light flux, and the third light flux. The number of layers can be reduced. Therefore, it is possible to reduce the production cost and to suppress the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51Q.
Even when the lens body 50 is made of an optical plastic, a crack occurs in the antireflection film 51Q due to the stress of the antireflection film 51Q, or the adhesion between the antireflection film 51Q and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Eighteenth embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1R according to the eighteenth embodiment includes an objective lens 5R instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5R includes a lens body 50 and an antireflection film 51R.

The antireflection film 51R is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical functional surfaces 52R and 53R. More specifically, the antireflection film 51R has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the film thickness of the antireflection film 5R is not uniform.
The optical function surfaces 52R and 53R have a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°] and 40 [ °] <θ⊥max <90 [°]
Alternatively, 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. Further, the optical function surfaces 52R and 53R have a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 ≦ λ ≦ λ3 + 15. In the case of [nm] and in the case of λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectivity is suppressed to 1 [%] or less. Further, the optical functional surfaces 52R and 53R exhibit a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. It has become.

The operation of the optical pickup device 1R described above is the same as that of the optical pickup device 1B in the third embodiment.
According to the optical pickup device 1R, the wavelength λ of the light beam perpendicularly incident on the optical functional surfaces 52R and 53R is λ1 ≦ λ ≦ λ1 + 15 [nm], and the case where λ2 ≦ λ ≦ λ2 + 15 [nm]. In the case of λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectivity at the optical functional surfaces 52R and 53R is 1% or less, and therefore reflection is prevented for wavelengths within these bands. Can do. Further, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents reflection of the entire light flux in a wide wavelength range of λ1 to λ3, the antireflection film 51R is obtained without impairing the antireflection function for the first light flux, the second light flux, and the third light flux. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51R can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51R due to the stress of the antireflection film 51R, or the adhesion between the antireflection film 51R and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

<Nineteenth embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1T according to the nineteenth embodiment includes an objective lens 5T instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5T includes a lens body 50 and an antireflection film 51T.

The antireflection film 51T is provided on at least one surface of the lens body 50, in this embodiment, both surfaces, and forms optical function surfaces 52T and 53T. More specifically, the antireflection film 51T has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5 [%]. The film is formed to be larger. That is, the thickness of the antireflection film 5T is not uniform.
The optical function surface 52G has a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] < θ⊥max <90 [°]
Alternatively, 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. The optical functional surface 52G has a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm], λ2 ≦ λ ≦ λ2 + 40 [nm], and λ3 ≦ λ ≦ λ3 + 30 [nm]. ], The reflectance is suppressed to 1% or less. Further, the optical functional surface 52G exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.
In the optical function surface 53G, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. The optical function surface 53G has a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 ≦ λ ≦ λ3 + 15 [nm]. ], The reflectance is suppressed to 1% or less. Further, the optical functional surface 53G exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1T described above is the same as that of the optical pickup device 1B in the third embodiment.
According to this optical pickup device 1T, the wavelength λ of the light beam perpendicularly incident on the optical function surface 53T is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 In the case of ≦ λ ≦ λ3 + 15 [nm], the reflectance at the optical function surface 53T is 1% or less, and the wavelength λ of the light beam perpendicularly incident on the optical function surface 52T is λ1 ≦ λ ≦ λ1 + 50 [nm]. , Λ2 ≦ λ ≦ λ2 + 40 [nm], and λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the optical functional surface 52T is 1% or less. Reflection can be prevented for wavelengths within these bands. Further, the optical function surface 53T exhibits a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, and the optical function surface 52T. In the case where the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, the antireflection function is lowered. Unlike the conventional antireflection film that prevents the reflection of the entire light flux in the wide wavelength range of λ1 to λ3, the antireflection film 51T does not impair the antireflection function for the first light flux, the second light flux, and the third light flux. The number of layers can be reduced. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51T can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51T due to the stress of the antireflection film 51T, or the adhesion between the antireflection film 51T and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In the present embodiment, the optical function surface 52T is described as a light incident surface, and the optical function surface 53T is described as a light output surface. However, the optical function surface 52T may be a light output surface and the optical function surface 53T may be a light output surface. good.

<20th Embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1U according to the twentieth embodiment includes an objective lens 5U instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5U includes a lens body 50 and an antireflection film 51U.

The antireflection film 51U is provided on at least one surface of the lens body 50, that is, both surfaces in the present embodiment, and forms optical functional surfaces 52U and 53U. More specifically, the antireflection film 51U has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the thickness of the antireflection film 5U is not uniform.
The optical function surface 52U has a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 40 [°] <θmax <90 [°] and 40 [°]. <Θ⊥max <90 [°]. Further, the optical function surface 52U is configured to suppress the reflectance to 1.5 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ3 + 120 [nm].
In the optical function surface 53U, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°]. ≦ θ⊥max ≦ 40 [°]. Further, the optical function surface 53U has a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 ≦ λ ≦ λ3 + 15 [nm]. ], The reflectance is suppressed to 1% or less. In addition, the optical functional surface 53U exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1U described above is the same as that of the optical pickup device 1B in the third embodiment.
According to this optical pickup device 1U, the wavelength λ of the light beam perpendicularly incident on the optical function surface 53U is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3 In the case of ≦ λ ≦ λ3 + 15 [nm], the reflectance at the optical function surface 53U is 1% or less, and the wavelength λ of the light beam perpendicularly incident on the optical function surface 52U is λ1 ≦ λ ≦ λ3 + 120 [ nm], the reflectance at the optical functional surface 52U is 1.5 [%] or less, and therefore reflection can be prevented for wavelengths within these bands. Further, in the optical function surface 53U, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. In contrast, the number of antireflection films 51U can be reduced without impairing the antireflection function for the first light flux, the second light flux, and the third light flux. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51U can be suppressed.
Even when the lens body 50 is made of an optical plastic, a crack occurs in the antireflection film 51U due to the stress of the antireflection film 51U, or the adhesion between the antireflection film 51U and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In the present embodiment, the optical function surface 52U is described as a light incident surface, and the optical function surface 53U is described as a light output surface. However, the optical function surface 52U may be a light output surface and the optical function surface 53U may be a light output surface. good.

<Twenty-first embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1V according to the twenty-first embodiment includes an objective lens 5V instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5V includes a lens body 50 and an antireflection film 51V.

The antireflection film 51V is provided on at least one surface of the lens main body 50, in this embodiment, both surfaces, and forms optical function surfaces 52V and 53V. More specifically, the antireflection film 51V has a {(maximum film thickness within the effective diameter for the first light beam) − (minimum film thickness within the effective diameter)} / average film thickness value of 5%. The film is formed to be larger. That is, the film thickness of the antireflection film 5V is not uniform.
The optical function surface 52V has a maximum incident / exit angle θmax within the effective diameter and a maximum surface angle θ⊥max within the effective diameter of 40 [°] <θmax <90 [°] and 40 [°]. <Θ⊥max <90 [°]. Further, the optical function surface 52V is configured to suppress the reflectance to 1.5 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ3 + 120 [nm].
In the optical function surface 53V, the maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 40 [°]. <Θ⊥max <90 [°]
Alternatively, 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°]. Further, the optical function surface 53V has a case where the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm], λ2 ≦ λ ≦ λ2 + 40 [nm], and λ3 ≦ λ ≦ λ3 + 30 [nm]. ], The reflectance is suppressed to 1% or less. Further, the optical functional surface 53V exhibits a maximum value with a reflectance larger than 1% when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1V described above is the same as that of the optical pickup device 1B in the third embodiment.
According to the optical pickup device 1V, the wavelength λ of the light beam perpendicularly incident on the optical function surface 53V is λ1 ≦ λ ≦ λ1 + 15 [nm], λ2 ≦ λ ≦ λ2 + 15 [nm], and λ3. In the case of ≦ λ ≦ λ3 + 15 [nm], the reflectance at the optical function surface 53V is 1% or less, and the wavelength λ of the light beam perpendicularly incident on the optical function surface 52V is λ1 ≦ λ ≦ λ3 + 120 [ nm], the reflectance at the optical functional surface 52V is 1.5 [%] or less, and therefore reflection can be prevented for wavelengths within these bands. Further, in the optical functional surface 53V, when the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. In contrast, the number of antireflection films 51V can be reduced without impairing the antireflection function for the first light flux, the second light flux, and the third light flux. Therefore, the production cost can be reduced, and the change in the spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51V can be suppressed.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51V due to the stress of the antireflection film 51V, or the adhesion between the antireflection film 51V and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In this embodiment, the optical function surface 52V is described as a light incident surface, and the optical function surface 53V is described as a light output surface. However, the optical function surface 52V may be a light output surface and the optical function surface 53V may be a light output surface. good.

<Twenty-second embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1W according to the twenty-second embodiment includes an objective lens 5W instead of the objective lens 5B.
As shown in FIG. 2, the objective lens 5W includes a lens body 50 and an antireflection film 51W.

The antireflection films 51W are provided on both surfaces of the lens body 50, and form optical function surfaces 52W and 53W.
The optical function surface 52W is configured to suppress the reflectance to 1 [%] or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ3 + 30 [nm].
The optical function surface 53W has a reflectance of 1% when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ3 + 30 [nm]. It is designed to keep it below. Further, the optical functional surface 53W exhibits a maximum value with a reflectance higher than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1W described above is the same as that of the optical pickup device 1B in the third embodiment.
According to the optical pickup device 1W, when the wavelength λ of the light beam perpendicularly incident on the optical function surface 52W is λ1 ≦ λ ≦ λ3 + 30 [nm], the reflectance at the optical function surface 52W is 1% or less. In the case where the wavelength λ of the light beam perpendicularly incident on the optical function surface 53W is λ1 ≦ λ ≦ λ1 + 50 [nm] and in the case where λ2 ≦ λ ≦ λ3 + 30 [nm], the optical function surface 53W Since the reflectance is 1 [%] or less, reflection can be prevented for wavelengths within these bands. Further, in the optical functional surface 53W, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, antireflection. Since the function is reduced, the number of layers of the antireflection film 51W can be reduced without impairing the antireflection function for the first light beam, the second light beam, and the third light beam, unlike the conventional case. Therefore, the production cost can be reduced, and the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51W can be suppressed.
Even when the lens body 50 is made of an optical plastic, a crack occurs in the antireflection film 51W due to the stress of the antireflection film 51W, or the adhesion between the antireflection film 51W and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

  In this embodiment, the optical function surface 52W is described as a light incident surface, and the optical function surface 53W is described as a light output surface. However, the optical function surface 52W may be a light output surface and the optical function surface 53W may be a light output surface. good.

<Twenty-third Embodiment>
Unlike the third optical pickup device 1B, the optical pickup device 1X according to the twenty-third embodiment includes an objective lens 5X instead of the objective lens 5B.
As shown in FIG. 4, the objective lens 5X includes two lens bodies 501, 502 and an antireflection film 51X.
The lens body 501 is disposed on the laser light sources 2a to 2c side, and the lens body 502 is disposed on the information recording medium side such as AOD100.

The antireflection film 51 </ b> X is provided on both surfaces of the lens bodies 501 and 502 to form optical function surfaces 54 to 57.
The optical functional surface 54 on the laser light sources 2a to 2c side and the optical functional surface 55 on the information recording medium side with respect to the lens body 501 have a case where the wavelength λ of the vertically incident light beam is λ = λ1, and λ = In the case of λ2 and the case of λ = λ3, the reflectance is suppressed to 1 [%] or less.
The optical functional surface 56 on the laser light sources 2a, 2b side with respect to the lens body 502 has a reflectance of 1% or less when the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ3 + 30 [nm]. It is supposed to be suppressed.
The optical function surface 57 on the information recording medium side with respect to the lens body 502 has a wavelength λ of a light beam incident perpendicularly to λ1 ≦ λ ≦ λ1 + 50 [nm] and λ2 ≦ λ ≦ λ3 + 30 [nm]. The reflectance is suppressed to 1% or less. The optical function surface 57 exhibits a maximum value with a reflectance larger than 1 [%] when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2. Yes.

The operation of the optical pickup device 1X described above is the same as that of the optical pickup device 1B in the third embodiment.
According to the optical pickup device 1X, when the wavelength λ of the light beam incident perpendicularly to the optical function surfaces 54 and 55 is λ = λ1, λ = λ2, and λ = λ3. When the reflectance at the optical function surfaces 54 and 55 is 1% or less and the wavelength λ of the light beam perpendicularly incident on the optical function surface 56 is λ1 ≦ λ ≦ λ3 + 30 [nm], the optical function surface The reflectance at 56 is 1% or less, and the wavelength λ of the light beam perpendicularly incident on the optical function surface 57 is λ1 ≦ λ ≦ λ1 + 50 [nm], and λ2 ≦ λ ≦ λ3 + 30 [nm]. In some cases, the reflectance at the optical function surface 57 is 1% or less, and therefore reflection can be prevented for wavelengths within these bands. Further, in the optical function surface 57, when the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%], that is, antireflection. Since the function is reduced, the number of layers of the antireflection film 51X can be reduced without impairing the antireflection function for the first light beam, the second light beam, and the third light beam, unlike the conventional case. Therefore, it is possible to reduce the production cost, and it is possible to suppress the change in spectral characteristics due to the penetration of moisture between the layers of the antireflection film 51X.
Even when the lens body 50 is made of optical plastic, a crack occurs in the antireflection film 51X due to the stress of the antireflection film 51X, or the adhesion between the antireflection film 51X and the lens body 50 decreases. Can be prevented, that is, environmental resistance can be improved.

In the first to twenty-third embodiments, the numerical apertures of the objective lenses 5, 5A to 5X have been described as 0.65, but may be 0.85 to 0.9. In this case, a Blu-ray disc having a protective substrate thickness of 0.1 mm can be used as an information recording medium in place of the AOD 100.
In the first to twelfth and fourteenth to twenty-second embodiments, the objective lens has been described as including one lens body and antireflection films provided on both surfaces of the lens body. Two or more lens bodies and an antireflection film provided on the surface of each lens body may be provided.
In the first to 23rd embodiments, the optical element has been described as the objective lens 5, but it may be a beam shrinker or a beam expander.

  Hereinafter, the present invention will be described more specifically by giving examples and comparative examples. In the following embodiments, the wavelength λ1 is 405 [nm], λ2 is 650 [nm], and λ3 is 780 [nm].

<Example 1>
In Example 1, the antireflection film 51 of the objective lens 5 in the first embodiment was configured with two layers as shown in Table 1. The lens body was formed of BK7 (trade name: manufactured by Shot Glass).

  As a result of measuring the relationship between the reflectance at the optical functional surfaces 52 and 53 of the objective lens 5 and the wavelength of the incident light, the reflectance of the optical functional surfaces 52 and 53 is determined as shown in FIG. Although the maximum value was 2% or more with λ2, it was 1% or less in the vicinity of the wavelengths λ1 and λ2, indicating a minimum value.

  Therefore, the objective lens 5 of the first embodiment has an antireflection function for the first light flux having the wavelength λ1 and the second light flux having the wavelength λ2, and recording / reproduction is prevented by preventing a decrease in the amount of transmitted light. It can be seen that the certainty can be improved.

<Example 2>
In Example 2, the antireflection film 51A of the objective lens 5A in the second embodiment was configured with three layers as shown in Table 2.

The relationship between the reflectance at the optical function surfaces 52A and 53A of the objective lens 5A and the wavelength of the incident light was measured.
As a result of the measurement, the reflectance on the optical functional surfaces 52A and 53A of the objective lens 5A shows a maximum value of 2% or more between the wavelength λ1 and the wavelength λ2, as shown in FIG. , Λ2 and 1% or less in a wide wavelength range.
Therefore, the objective lens 5A of the second embodiment has an antireflection function for the first light flux having the wavelength λ1 and the second light flux having the wavelength λ2, and recording / reproduction can be prevented by preventing a decrease in the transmitted light amount. It turns out that certainty can be improved.

<Example 3>
In Example 3, the antireflection film 51B of the objective lens 5B in the third embodiment was configured with four layers as shown in Table 3.

  As a result of measuring the relationship between the reflectance at the optical function surfaces 52B and 53B of the objective lens 5B and the wavelength of the incident light, the reflectance at the optical function surfaces 52B and 53B is the wavelength λ1 and the wavelength as shown in FIG. Although the maximum value is 2% or more with λ2, it is 1% or less in the vicinity of the wavelengths λ1, λ2, and λ3.

  Therefore, the objective lens 5B of Example 3 has an antireflection function with respect to the first light flux having the wavelength λ1, the second light flux having the wavelength λ2, and the third light flux having the wavelength λ3. It can be seen that the reliability of recording / reproduction can be improved by preventing the decrease in the recording medium.

<Example 4>
In Example 4, the antireflection film 51B of the objective lens 5B in the third embodiment was configured with six layers as shown in Table 4.

As a result of measuring the relationship between the reflectance on the optical functional surfaces 52B and 53B of the objective lens 5B and the wavelength of the incident light, the reflectance on the optical functional surfaces 52B and 53B is the wavelength λ1 and the wavelength as shown in FIG. Although the maximum value is 2% or more with λ2, it is 1% or less in the vicinity of the wavelengths λ1, λ2, and λ3.
Therefore, the objective lens 5B of the fourth embodiment has an antireflection function for the first light flux with the wavelength λ1, the second light flux with the wavelength λ2, and the third light flux with the wavelength λ3, and the transmitted light amount. It can be seen that the reliability of recording / reproduction can be improved by preventing the decrease in the recording medium.

<Example 5>
In Example 5, the objective lens 5C in the fourth, fifth, and sixth embodiments was configured as shown in Table 5 as a so-called two-lens lens. The lens having a two-lens configuration is provided with two lens bodies. The focal length of the objective lens 5C was 2.2 [mm] with respect to a light beam having a wavelength of 408 [nm].

ここで、表５中、Ｓ１〜Ｓ４はそれぞれ対物レンズ５Ｃの光学機能面であり、レーザー光源２ａ，２ｂからＡＯＤ１００等の情報記録媒体に向かってＳ１〜Ｓ４の順に位置している。

Here, in Table 5, S1 to S4 are optical function surfaces of the objective lens 5C, and are positioned in the order of S1 to S4 from the laser light sources 2a and 2b toward the information recording medium such as AOD100.

  More specifically, the optical functional surfaces S1 and S2 are formed of an antireflection film having a two-layer structure shown in Table 1 above. The optical functional surfaces S3 and S4 were formed by an antireflection film having a seven-layer structure shown in Table 6.

As a result of measuring the transmittance of the objective lens 5C, the transmittance with respect to the light beam with a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to the light beam with a wavelength of 658 [nm] is 98 [%]. showed that.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5C on the optical functional surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical functional surfaces S1 and S2 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1 and λ2.
Further, as a result of measuring the relationship between the reflectance at the optical function surfaces S3 and S4 of the objective lens 5C and the wavelength of the incident light, the reflectance at the optical function surfaces S3 and S4 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1 and λ2.
Therefore, the objective lens 5C in the fifth embodiment has an antireflection function for the first and second light beams by the antireflection film 51C having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 6>
In Example 6, the objective lens 5O in the fourteenth, fifteenth, and sixteenth embodiments was configured as a so-called two-lens configuration lens as shown in Table 5 above.

  More specifically, the optical functional surfaces S1 and S2 are formed of an antireflection film having a six-layer structure shown in Table 4 above. The optical functional surfaces S3 and S4 were formed by an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittance of the objective lens 5O, the transmittance with respect to a light beam having a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to a light beam having a wavelength of 658 [nm] is 98 [%] and 785 [nm]. The transmittance with respect to a light flux having a wavelength of 97% was a good value of 97%.
Further, as a result of measuring the relationship between the reflectance on the optical function surfaces S1 and S2 of the objective lens 5O and the wavelength of the incident light, the reflectance on the optical function surfaces S1 and S2 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1, λ2, and λ3.
Further, as a result of measuring the relationship between the reflectance at the optical function surfaces S3 and S4 of the objective lens 5O and the wavelength of the incident light, the reflectance at the optical function surfaces S3 and S4 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1, λ2, and λ3.
Thus, the objective lens 5O in the sixth embodiment has an antireflection function for the first to third light beams by the antireflection film 51O having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 7>
In Example 7, the objective lenses 5F, 5I, 5J, and 5K in the seventh, ninth, tenth, eleventh, and thirteenth embodiments were configured as shown in Table 5 as so-called two-lens lenses.

  More specifically, the optical functional surfaces S1 and S2 are formed of an antireflection film having a two-layer structure shown in Table 1 above. The optical function surface S3 was formed of an antireflection film having a five-layer structure shown in Table 7. The optical function surface S4 was formed of an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittance of this objective lens, the transmittance with respect to the light beam with a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to the light beam with a wavelength of 658 [nm] is 98 [%]. Indicated.
Further, as a result of measuring the relationship between the reflectance of the objective lenses 5F, 5I, 5J and 5K on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is shown in FIG. Thus, although the maximum value of 1 [%] or more is shown between the wavelength λ1 + 15 [nm] and the wavelength λ2, it is 1 [%] or less near the wavelengths λ1 and λ2, indicating the minimum value.
Further, as a result of measuring the relationship between the reflectance on the optical function surface S3 and the wavelength of the incident light, the reflectance of the optical function surface S3 is 1.5 [% near the wavelengths λ1 and λ2, as shown in FIG. It was as follows.
Further, as a result of measuring the relationship between the reflectance of the optical function surface S4 and the wavelength of the incident light, the reflectance of the optical function surface S4 is between the wavelength λ1 + 50 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1 and λ2.
Therefore, the objective lens in Example 7 has an antireflection function for the first and second light fluxes by an antireflection film having a small number of layers, and recording / reproduction can be prevented by preventing a decrease in the amount of transmitted light. It turns out that certainty can be improved.

<Example 8>
In Example 8, the objective lenses 5Q, 5T, 5U, and 5W in the seventeenth, nineteenth, twenty, twenty-first, and twenty-third embodiments are configured as shown in Table 5 as so-called two-lens lenses.

  More specifically, the optical functional surfaces S1 and S2 are formed of an antireflection film having a six-layer structure shown in Table 4 above. The optical function surface S3 was formed of an antireflection film having a nine-layer structure shown in Table 8. The optical function surface S4 was formed of an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittances of the objective lenses 5Q, 5T, 5U, and 5W, the transmittance with respect to a light beam having a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to a light beam having a wavelength of 658 [nm] is 98 [%. ] The transmittance with respect to a light beam having a wavelength of 785 [nm] was 97 [%], which was a good value.
Further, as a result of measuring the relationship between the reflectance of the objective lenses 5Q, 5T, 5U, and 5W on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is shown in FIG. Thus, although the maximum value of 1 [%] or more is shown between the wavelength λ1 + 15 [nm] and the wavelength λ2, it is 1 [%] or less in the vicinity of the wavelengths λ1, λ2, and λ3.
Further, as a result of measuring the relationship between the reflectance on the optical function surface S3 and the wavelength of the incident light, the reflectance of the optical function surface S3 is 1.5 in the vicinity of the wavelengths λ1, λ2, and λ3 as shown in FIG. [%] Or less.
Further, as a result of measuring the relationship between the reflectance of the optical function surface S4 and the wavelength of the incident light, the reflectance of the optical function surface S4 is between the wavelength λ1 + 50 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1, λ2, and λ3.
Accordingly, the objective lenses 5Q, 5T, 5U, and 5W in the eighth embodiment have an antireflection function for the first to third light beams by the antireflection films 51Q, 51T, 51U, and 51W having a small number of layers. It can be seen that the reliability of recording and reproduction can be improved by preventing the decrease in the amount of transmitted light.

<Example 9>
In Example 9, the objective lens 5D in the fifth embodiment was configured as a so-called single lens as shown in Table 9. The focal length of the objective lens 5E is 2.0 [mm] with respect to a light beam having a wavelength of 405 [nm].

ここで、表９中、Ｓ１，Ｓ２はそれぞれ対物レンズ５Ｄの光学機能面であり、レンズ本体５０に対して、Ｓ１はレーザー光源２ａ，２ｂ側に、Ｓ２はＡＯＤ１００等の情報記録媒体側に位置している。

Here, in Table 9, S1 and S2 are optical function surfaces of the objective lens 5D, respectively, with respect to the lens body 50, S1 is located on the laser light sources 2a and 2b side, and S2 is located on the information recording medium side such as AOD100. is doing.

  More specifically, the optical functional surfaces S1 and S2 are formed of an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittance of the objective lens 5D, the transmittance with respect to the light beam with the wavelength of 408 [nm] is 98 [%], and the transmittance with respect to the light beam with the wavelength of 658 [nm] is 98 [%]. showed that.
Further, as a result of measuring the relationship between the reflectance at the optical function surfaces S1 and S2 of the objective lens 5D and the wavelength of the incident light, the reflectance at the optical function surfaces S1 and S2 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1 and λ2.
Therefore, the objective lens 5D in Example 9 has an antireflection function for the first and second light beams by the antireflection film 51D having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 10>
In Example 10, the objective lens 5O in the fifteenth embodiment was configured as a so-called single lens as shown in Table 9 above.

  More specifically, the optical functional surfaces S1 and S2 are formed of an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittance of the objective lens 5O, the transmittance with respect to a light beam having a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to a light beam having a wavelength of 658 [nm] is 98 [%] and 785 [nm]. The transmittance with respect to a luminous flux having a wavelength of 97% was a good value of 97%.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5O on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1, λ2, and λ3.
From this, the objective lens 5O in Example 10 has an antireflection function for the first to third light beams by the antireflection film 51O having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 11>
In Example 11, the objective lens 5K in the eleventh and twelfth embodiments was configured as a so-called single lens as shown in Table 9 above.

  More specifically, the optical functional surface S1 was formed by an antireflection film having a five-layer structure shown in Table 7 above, and S2 was formed by an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittance of the objective lens 5K, the transmittance with respect to the light beam with a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to the light beam with a wavelength of 658 [nm] is 98 [%]. showed that.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5K on the optical function surface S1 and the wavelength of the incident light, the reflectance of the optical function surface S1 is determined as follows: wavelength λ1 + 15 [nm] and wavelength as shown in FIG. Although the maximum value is 1% or more with λ2, it is 1% or less near the wavelengths λ1 and λ2.
Further, as a result of measuring the relationship between the reflectance on the optical functional surface S2 and the wavelength of the incident light, the reflectance of the optical functional surface S2 is between the wavelength λ1 + 15 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1 and λ2.
Therefore, the objective lens 5K in the present Example 11 has an antireflection function for the first and second light beams by the antireflection film 51K having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 12>
In Example 12, the objective lens 5V in the 21st and 22nd embodiments was configured as a so-called single lens as shown in Table 9 above.

  More specifically, the optical functional surface S1 was formed by an antireflection film having a nine-layer structure shown in Table 8 above, and S2 was formed by an antireflection film having a seven-layer structure shown in Table 6 above.

As a result of measuring the transmittance of the objective lens 5V, the transmittance with respect to a light beam with a wavelength of 408 [nm] is 98 [%], and the transmittance with respect to a light beam with a wavelength of 658 [nm] is 98 [%] and 785 [nm]. The transmittance with respect to a light flux having a wavelength of 97% was a good value of 97%.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5V on the optical function surface S1 and the wavelength of the incident light, the reflectance of the optical function surface S1 is as shown in FIG. 11 with wavelengths λ1, λ2, and λ3. It was 1% or less in the vicinity.
Further, as a result of measuring the relationship between the reflectance on the optical functional surface S2 and the wavelength of the incident light, the reflectance of the optical functional surface S2 is between the wavelength λ1 + 15 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1, λ2, and λ3.
Therefore, the objective lens 5V in Example 12 has an antireflection function for the first to third light beams by the antireflection film 51V having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 13>
In Example 13, the objective lens 5W in the fifteenth embodiment is a so-called single lens, and the optical functional surfaces S1 and S2 are formed of an antireflection film having a 10-layer structure shown in Table 11. The antireflection film {(maximum film thickness within the effective diameter) − (minimum film thickness within the effective diameter)} / average film thickness is 5% or less, and the film thickness distribution is uniform. .

In the optical pickup device 1W using the objective lens 5W, it was possible to reliably perform recording / reproduction with the first to third light beams. Further, when the transmittances of the P-polarized light and the S-polarized light of the first to third light beams in the objective lens 5W were measured, they were almost equal as shown in Table 10.

  Further, as a result of measuring the relationship between the reflectance of the objective lens 5W on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1, λ2, and λ3.

  Therefore, the objective lens 5W in Example 13 has an antireflection function for the first to third light beams by the antireflection film 51W having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved. It can also be seen that the reliability of recording and reproduction can be further improved because the incident light quantity of the photodetector does not decrease due to the difference in transmittance between the P-polarized light and the S-polarized light.

<Example 14>
In Example 14, the objective lens 5W in the twenty-second embodiment is a so-called single-lens lens, the optical functional surface S1 is formed of an antireflection film having a nine-layer structure shown in Table 12, and the optical functional surface S2 is a front surface. An antireflection film having a nine-layer structure shown in FIG. The antireflection film {(maximum film thickness within the effective diameter) − (minimum film thickness within the effective diameter)} / average film thickness is 5% or less, and the film thickness distribution is uniform. .

In the optical pickup device 1W using the objective lens 5W, it was possible to reliably perform recording / reproduction with the first to third light beams.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5W on the optical function surface S1 and the wavelength of the incident light, the reflectance of the optical function surface S1 is determined as follows: wavelength λ1 + 50 [nm] and wavelength as shown in FIG. Although the maximum value is 1% or more with λ2, it is 1% or less in the vicinity of the wavelengths λ1, λ2, and λ3.
Further, as a result of measuring the relationship between the reflectance on the optical function surface S2 and the wavelength of the incident light, the reflectance of the optical function surface S2 is between the wavelength λ1 + 50 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1, λ2, and λ3.

  Therefore, the objective lens 5W in Example 14 has an antireflection function for the first to third light beams by the antireflection film 51W having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 15>
In Example 15, the objective lens 5W in the twenty-second embodiment is a so-called single-lens lens, the optical function surface S1 is formed of an antireflection film having a nine-layer structure shown in Table 12, and the optical function surface S2 is The antireflection film having a nine-layer structure shown in Table 13 was formed. The value of {(maximum film thickness within the effective diameter) − (minimum film thickness within the effective diameter)} / average film thickness of the antireflection film is larger than 5%, and the film thickness distribution is uneven. It was.

  When the transmittance of the objective lens 5W was measured, the transmittance was slightly lower than that of the objective lens 5W of Example 14, but the first example of the optical pickup device 1W using the objective lens 5W of Example 15 is also the first. Recording / reproduction can be reliably performed by the third light beam.

  Therefore, the objective lens 5W in Example 15 has an antireflection function for the first to third light beams by the antireflection film 51W having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 16>
In Example 16, the objective lens 5X in the fourteenth, fifteenth and sixteenth embodiments is a so-called two-lens lens, and the optical functional surfaces S1 and S2 are formed by an antireflection film having a six-layer structure shown in Table 4 above. The optical functional surfaces S3 and S4 were formed by an antireflection film having a 10-layer structure shown in Table 11 above. The antireflection film {(maximum film thickness within the effective diameter) − (minimum film thickness within the effective diameter)} / average film thickness is 5% or less, and the film thickness distribution is uniform. .

In the optical pickup device 1X using the objective lens 5X, recording and reproduction can be reliably performed by the first to third light beams. Further, when the transmittances of the P-polarized light and the S-polarized light of the first to third light beams in the objective lens 5X were measured, they were almost equal as shown in Table 14.

Further, as a result of measuring the relationship between the reflectance of the objective lens 5X on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is as shown in FIG. The maximum value between 1 nm and the wavelength λ2 is 1% or more, but it is 1% or less near the wavelengths λ1, λ2, and λ3.
Further, as a result of measuring the relationship between the reflectivity at the optical function surfaces S3 and S4 and the wavelength of the incident light, the reflectivity at the optical function surfaces S3 and S4 is as shown in FIG. However, it was 1 [%] or less in the vicinity of the wavelengths [lambda] 1, [lambda] 2, [lambda] 3.

  Therefore, the objective lens 5X in Example 16 has an antireflection function for the first to third light beams by the antireflection film 51X having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved. It can also be seen that the reliability of recording and reproduction can be further improved because the incident light quantity of the photodetector does not decrease due to the difference in transmittance between the P-polarized light and the S-polarized light.

<Example 17>
In Example 17, the objective lens 5X in the twenty-third embodiment is a so-called two-lens lens, and the optical function surfaces S1 and S2 are formed by an antireflection film having a six-layer structure shown in Table 4 above. S3 was formed by an antireflection film having a nine-layer structure shown in Table 12 above, and the optical functional surface S4 was formed by an antireflection film having a nine-layer structure shown in Table 13 above. The antireflection film {(maximum film thickness within the effective diameter) − (minimum film thickness within the effective diameter)} / average film thickness is 5% or less, and the film thickness distribution is uniform. .

In the optical pickup device 1X using the objective lens 5X, recording and reproduction can be reliably performed by the first to third light beams.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5X on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is as shown in FIG. Although the maximum value is 1% or more with respect to the wavelength λ2, it is 1% or less near the wavelengths λ1, λ2, and λ3.
Further, as a result of measuring the relationship between the reflectance on the optical functional surface S3 and the wavelength of the incident light, the reflectance of the optical functional surface S3 is 1% in the vicinity of the wavelengths λ1, λ2, and λ3 as shown in FIG. It was as follows.
Further, as a result of measuring the relationship between the reflectance at the optical function surface S4 and the wavelength of the incident light, the reflectance at the optical function surface S4 is between the wavelength λ1 + 50 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1, λ2, and λ3.

  Therefore, the objective lens 5X in Example 17 has an antireflection function for the first to third light beams by the antireflection film 51X having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

<Example 18>
In Example 18, the objective lens 5X in the twenty-third embodiment is a so-called two-lens lens, and the optical functional surfaces S1 and S2 are formed by an antireflection film having a six-layer structure shown in Table 4 above. S3 was formed by an antireflection film having a nine-layer structure shown in Table 12 above, and the optical functional surface S4 was formed by an antireflection film having a nine-layer structure shown in Table 13 above. The value of {(maximum film thickness within the effective diameter) − (minimum film thickness within the effective diameter)} / average film thickness of the antireflection film is larger than 5%, and the film thickness distribution is uneven. It was.

When the transmittance of the objective lens 5X was measured, the transmittance was slightly lower than that of the objective lens 5X of Example 17, but the first example of the optical pickup device 1X using the objective lens 5X of Example 18 is also the first. Recording / reproduction can be reliably performed by the third light beam.
Further, as a result of measuring the relationship between the reflectance of the objective lens 5X on the optical function surfaces S1 and S2 and the wavelength of the incident light, the reflectance of the optical function surfaces S1 and S2 is as shown in FIG. Although the maximum value is 1% or more with respect to the wavelength λ2, it is 1% or less near the wavelengths λ1, λ2, and λ3.
Further, as a result of measuring the relationship between the reflectance on the optical functional surface S3 and the wavelength of the incident light, the reflectance of the optical functional surface S3 is 1% in the vicinity of the wavelengths λ1, λ2, and λ3 as shown in FIG. It was as follows.
Further, as a result of measuring the relationship between the reflectance at the optical function surface S4 and the wavelength of the incident light, the reflectance at the optical function surface S4 is between the wavelength λ1 + 50 [nm] and the wavelength λ2, as shown in FIG. Although the maximum value was 1 [%] or more, it was 1 [%] or less in the vicinity of the wavelengths λ1, λ2, and λ3.

  Therefore, the objective lens 5X in Example 18 has an antireflection function for the first to third light beams by the antireflection film 51X having a small number of layers, and recording is performed by preventing a decrease in the amount of transmitted light. It turns out that the certainty of reproduction can be improved.

It is a figure which shows schematic structure of the optical pick-up apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the objective lens which concerns on this invention. It is a figure which shows schematic structure of other embodiment of the optical pick-up apparatus based on this invention. It is a longitudinal cross-sectional view which shows other embodiment of the objective lens which concerns on this invention. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 1. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 2. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 3. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 4. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 6. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 7. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 8. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 11. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the antireflection film of Table 12. It is a figure which shows the spectral reflectance curve in the optical function surface formed of the anti-reflective film of Table 13.

Explanation of symbols

1, 1A to 1X Optical pickup device 2a to 2c Laser light source 5, 5A to 5X Objective lens (optical element)
50 Lens body 51, 51A to 51X Antireflection film 52, 52A to 52X, 53, 53A to 53X Optical functional surface 501 Lens body (first optical element body)
502 Lens body (second optical element body)

Claims (35)

Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 800 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body to form at least one optical functional surface,
An optical element characterized in that the reflectance of a light beam perpendicularly incident on the optical function surface exhibits a maximum value of 1% or more between the wavelength λ1 and the wavelength λ2. The optical element according to claim 1, wherein
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical element according to claim 1, wherein the wavelength λ2 satisfies 630 [nm] ≦ λ2 ≦ 670 [nm]. The optical element according to claim 1 or 2,
An optical element characterized in that the maximum incident / exit angle θmax of the light flux having the wavelength λ1 on the optical function surface is 0 [°] ≦ θmax ≦ 40 [°]. In the optical element as described in any one of Claims 1-3,
The refractive index n ₀ of the optical element body is 1.45 ≦ n ₀ ≦ 1.65,
Of the layers included in the antireflection film, the first layer located closest to the optical element body has a refractive index n ₁ of 1.7 ≦ n ₁ ≦ 2.5 and an optical film thickness nd ₁ of 225 [nm. ] ≦ nd ₁ ≦ 275 [nm],
Second, the second layer located on the optical element body side has a refractive index n ₂ of 1.3 ≦ n ₂ ≦ 1.55 and an optical film thickness nd ₂ of 100 [nm] ≦ nd ₂ ≦ 150 [nm]. An optical element characterized by the above. In the optical element as described in any one of Claims 1-3,
The refractive index n ₀ of the optical element body is 1.45 ≦ n ₀ ≦ 1.65,
Of the layers included in the antireflection film, the first layer located closest to the optical element body has a refractive index n ₁ of 1.7 ≦ n ₁ ≦ 2.5 and an optical film thickness nd ₁ of 125 [nm. ] ≦ nd ₁ ≦ 175 [nm],
Second, the second layer located on the optical element body side has a refractive index n ₂ of 1.55 ≦ n ₂ <1.7 and an optical film thickness nd ₂ of 75 [nm] ≦ nd ₂ ≦ 125 [nm]. And
Third, the third layer located on the optical element body side has a refractive index n ₃ of 1.3 ≦ n ₃ <1.55 and an optical film thickness nd ₃ of 100 [nm] ≦ nd ₃ ≦ 150 [nm]. An optical element characterized by the above. In the optical element as described in any one of Claims 1-3,
The refractive index n ₀ of the optical element body is 1.45 ≦ n ₀ ≦ 1.65,
Of the layers included in the antireflection film, the first layer located closest to the optical element body has a refractive index n ₁ of 1.7 ≦ n ₁ ≦ 2.5 and an optical film thickness nd ₁ of 25 [nm. ] ≦ nd ₁ ≦ 75 [nm],
Second, the second layer located on the optical element body side has a refractive index n ₂ of 1.3 ≦ n ₂ ≦ 1.55 and an optical film thickness nd ₂ of 25 [nm] ≦ nd ₂ ≦ 75 [nm]. And
Third, the third layer located on the optical element body side has a refractive index n ₃ of 1.7 ≦ n ₃ ≦ 2.5 and an optical film thickness nd ₃ of 225 [nm] ≦ nd ₃ ≦ 275 [nm]. And
The fourth layer located fourth on the optical element body side has a refractive index n ₄ of 1.3 ≦ n ₄ ≦ 1.55 and an optical film thickness nd ₄ of 135 [nm] ≦ nd ₄ ≦ 185 [nm]. An optical element characterized by the above. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is 5% or less. Forming at least two optical functional surfaces having a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 15 [nm] <λ <λ2. The optical element according to claim 7.
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface is:
When the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm], the reflectance is 1 [%] or less. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is 5% or less. Forming at least two optical functional surfaces having a maximum incident / exit angle θmax within the effective diameter of 40 [°] <θmax <90 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. The optical element according to claim 9, wherein
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface is:
When the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is 5% or less. The first optical function surface having a maximum incident / exit angle θmax within the effective diameter of 0 [°] ≦ θmax ≦ 40 [°], and the maximum incident / exit angle θmax within the effective diameter of 40 [°] < and at least one second optical functional surface satisfying θmax <90 [°],
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength within the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. The optical element according to claim 11, wherein
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm],
The optical element according to claim 2, wherein the second optical functional surface has a reflectance of 1 [%] or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm]. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed such that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ Forming at least two optical functional surfaces of 40 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
An optical element characterized in that when the wavelength λ is a certain wavelength within a range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%]. The optical element according to claim 13.
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm]. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] <θ⊥max < 90 [°]
Or forming at least two optical functional surfaces satisfying 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°],
These optical functional surfaces
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. The optical element according to claim 15, wherein
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The optical functional surface has an reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm]. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ At least one first optical functional surface of 40 [°];
0 [°] ≦ θmax ≦ 40 [°] and 40 [°] <θ⊥max <90 [°]
Or 40 [°] <θmax <90 [°] and at least one second optical functional surface satisfying 0 [°] ≦ θ⊥max ≦ 40 [°],
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength in the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. The optical element according to claim 17,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm],
The optical element according to claim 2, wherein the second optical functional surface has a reflectance of 1 [%] or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm]. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 0 [°] ≦ θ⊥max ≦ At least one first optical functional surface of 40 [°];
40 [°] <θmax <90 [°] and at least one second optical functional surface satisfying 40 [°] <θ⊥max <90 [°], wherein the first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 15 [nm] and when λ2 ≦ λ ≦ λ2 + 15 [nm], the reflectance is 1 [%] or less,
When the wavelength λ is a certain wavelength in the range of λ1 + 15 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ2 + 130 [nm], the reflectance is 1.5 [%] or less. The optical element according to claim 19, wherein
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 15 [nm],
The second optical functional surface has an reflectance of 1.5 [%] or less when the wavelength λ is λ1 ≦ λ ≦ λ3 + 120 [nm]. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
One or more optical element bodies, and an antireflection film provided on the surface of the optical element body,
The antireflection film is
{(Maximum film thickness within the effective diameter for the light beam having the wavelength λ1) − (Minimum film thickness within the effective diameter)} / The film is formed so that the average film thickness is greater than 5%. The maximum incident / exit angle θmax within the effective diameter and the maximum surface angle θ⊥max within the effective diameter are 0 [°] ≦ θmax ≦ 40 [°] and 40 [°] <θ⊥max < 90 [°]
Or at least one first optical functional surface satisfying 40 [°] <θmax <90 [°] and 0 [°] ≦ θ⊥max ≦ 40 [°],
Forming at least one second optical functional surface satisfying 40 [°] <θmax <90 [°] and 40 [°] <θ⊥max <90 [°],
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
When the wavelength λ is a certain wavelength within the range of λ1 + 50 [nm] <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ2 + 130 [nm], the reflectance is 1.5 [%] or less. The optical element according to claim 21, wherein
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface has a reflectance of 1% or less when the wavelength λ is λ3 ≦ λ ≦ λ3 + 30 [nm],
The second optical functional surface has an reflectance of 1.5 [%] or less when the wavelength λ is λ1 ≦ λ ≦ λ3 + 120 [nm]. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
An optical element body, and an antireflection film provided on both surfaces of the optical element body and forming a first optical functional surface on the laser light source side and a second optical functional surface on the information recording medium side of the optical pickup device. Prepared,
The first optical functional surface is
When the wavelength λ of the vertically incident light beam is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
The second optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less,
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. 24. The optical element according to claim 23.
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less,
The second optical functional surface is
When the wavelength λ is λ2 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less. Provided in an optical pickup device that records and / or reproduces information, and includes a plurality of wavelengths λ1 (390 [nm] ≦ λ1 ≦ 430 [nm]) and wavelengths λ2 (630 [nm] ≦ λ2 ≦ 670 [nm]) An optical element for condensing a light beam having a wavelength of
A first optical element body disposed on the laser light source side of the optical pickup device;
A second optical element body disposed on the information recording medium side;
Provided on both surfaces of the first optical element body to form a first optical functional surface on the laser light source side and a second optical functional surface on the information recording medium side, and provided on both surfaces of the second optical element body An antireflection film formed with a third optical functional surface on the laser light source side and a fourth optical functional surface on the information recording medium side,
The first optical functional surface and the second optical functional surface are:
When the wavelength λ of the vertically incident light beam is λ = λ1 and λ = λ2, the reflectance is 1% or less,
When the wavelength λ is a certain wavelength within the range of λ1 <λ <λ2, the reflectance shows a maximum value larger than 1 [%],
The third optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1 [%] or less,
The fourth optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ1 + 50 [nm] and when λ2 ≦ λ ≦ λ2 + 40 [nm], the reflectance is 1% or less.
An optical element, wherein the reflectance exhibits a maximum value larger than 1 [%] when the wavelength λ is a certain wavelength within a range of λ1 + 50 [nm] <λ <λ2. The optical element according to claim 25,
The plurality of wavelengths include a wavelength λ3 (760 [nm] ≦ λ3 ≦ 800 [nm]),
The first optical functional surface and the second optical functional surface are:
When the wavelength λ is λ = λ3, the reflectance is 1% or less,
The third optical functional surface is
When the wavelength λ is λ1 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less,
The fourth optical functional surface is
When the wavelength λ is λ2 ≦ λ ≦ λ3 + 30 [nm], the reflectance is 1 [%] or less. In the optical element according to any one of claims 1 to 26,
An optical element characterized by being an objective lens having a numerical aperture of 0.65 or more. In the optical element according to any one of claims 1 to 27,
The antireflection film includes a low refractive index material having a refractive index n of 1.3 ≦ n ≦ 1.55 with respect to a light beam having a wavelength of 500 [nm];
An optical element characterized by being formed of at least two types of materials among high refractive index materials satisfying 1.7 ≦ n ≦ 2.5. The optical element according to claim 28, wherein
The low refractive index material is a material mainly composed of MgF ₂ or SiO ₂ ,
The optical element, wherein the high refractive index material is a material mainly composed of TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZrO ₂ , HfO ₂ or CeF ₃ . In the optical element according to any one of claims 1 to 27,
The antireflection film includes a low refractive index material having a refractive index n of 1.3 ≦ n <1.55 with respect to a light beam having a wavelength of 500 [nm];
A medium refractive index material with 1.55 ≦ n <1.7;
An optical element characterized by being formed of at least three kinds of materials among high refractive index materials satisfying 1.7 ≦ n <2.5. The optical element according to claim 30, wherein
The low refractive index material is a material mainly composed of MgF ₂ or SiO ₂ ,
The medium refractive index material is a material mainly composed of Al ₂ O ₃ ,
The optical element, wherein the high refractive index material is a material mainly composed of TiO ₂ , Ta ₂ O ₅ , CeO ₂ , ZrO ₂ , HfO ₂ or CeF ₃ . In the optical element as described in any one of Claims 1-31,
The optical element body is plastic molded. In the optical element as described in any one of Claims 1-31,
The optical element body is formed by glass molding. In the optical element as described in any one of Claims 1-33,
A base layer is interposed between the optical element body and the antireflection film,
The refractive index n ₀ of the base layer ', the refractive index of the optical element body when the n _0, | n _0' -n ₀ | optical element which is a ≦ 0.1. The optical element according to any one of claims 1 to 34 and a laser light source,
At least one of recording information on the optical recording medium and reproducing information recorded on the optical recording medium by condensing the light beam emitted from the laser light source onto the optical recording medium by the optical element. An optical pickup device capable of executing one of them.

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