CN102007538A - Objective lens and optical pickup device - Google Patents

Abstract

An optical pickup device and an objective lens which allow simple configuration and reduced costs of the optical pickup device by properly recording and/or reproducing information in/from three kinds of disks of different recording densities. On the optical surface of the objective lens, an optical path difference imparting structure is formed. The optical path difference imparting structure is obtained by superimposing a first foundation structure being a blazed structure and a second foundation structure being a stepped structure such that the positions of all the step portions of the first foundation structure coincide with the positions of the step portions of the second foundation structure.

Description

Object lens and optical take-up apparatus

Technical field

The present invention relates to and to exchange optical take-up apparatus and the use therein object lens that carry out information record and/or regeneration possibly to different types of CD.

Background technology

In recent years, in the optical take-up apparatus, as being used for the information of reproduced light disc recording and to the light source of cd-rom recording of information, the short wavelengthization of the LASER Light Source of using is made progress to some extent, for example, bluish violet semiconductor laser and utilize second harmonic to carry out the LASER Light Source practicability more and more of the blue SHG laser equiwavelength 400～420nm of infrared semiconductor laser wavelength conversion.Use the words of these bluish violet color laser light sources, when the object lens that use with DVD (digital universal disc) identical numerical aperture (NA), can write down the information of 15～20GB to the CD of diameter 12cm, the NA of object lens is brought up at 0.85 o'clock, can write down the information of 23～25GB to the CD of diameter 12cm.In this instructions, will use the CD and the photomagneto disk of bluish violet color laser light source to be generically and collectively referred to as " high density compact disc ".

When using the high density compact disc of NA 0.85 object lens; increase owing to resulting from the coma aberration that disc tilt (skew) produces; so the protective seam that has also thin when designing than DVD (having only 0.1mm with respect to the 0.6mm of DVD) is to reduce the coma aberration amount that tilts to cause.But, only can be to such high density compact disc recording/reproducing information definitely, also insufficient as the value of dvd playback/sound-track engraving apparatus (optical information recording regenerator) product.Now, consider the DVD that writing down variety of information and the present situation of CD (mini disk) sale, light can be to high density compact disc recording/reproducing information not enough, DVD and CD that for example user is held can carry out the information recording/reproducing equally definitely, are only the only way which must be passed of the commodity value of dvd playback/sound-track engraving apparatus that raising uses as high density compact disc.For this background, wish to carry at high density compact disc and have not only any performance of all keeping interchangeability but also can carrying out the information recording/reproducing definitely high density compact disc, DVD, CD with the optical take-up apparatus in dvd playback/sound-track engraving apparatus.

As not only to any method of all keeping interchangeability but also can carrying out the information recording/reproducing definitely of high density compact disc, DVD, CD, the recording density that can consider the CD of corresponding information recording/reproducing is optionally switched high density compact disc is used optical system with optical system and DVD, CD method, but need a plurality of optical systems like this, be unfavorable for miniaturization, cost rises in addition.

Therefore, realize low cost, in having the optical take-up apparatus of interchangeability, also preferably make high density compact disc, reduce the optic number of packages that constitutes optical take-up apparatus as far as possible with optical system and DVD, CD optical system universalization in order to simplify the optical take-up apparatus structure.Yet, make way facing to the object lens universalization of CD configuration, be to help optical take-up apparatus designs simplification and cost degradation most.For obtaining can be to the object lens of the common use of the mutually different multiple CD of recording/reproducing wavelength; the optical path difference that must form the wavelength interdependence with spherical aberration in to object optical system is paid structure, reduces the different different spherical aberrations that cause generation with protective layer thickness of wavelength

In the patent documentation 1 optical element of record be used to have optical path difference pays structure can be to the object lens of high density compact disc and DVD in the past, the common use of CD.

The look-ahead technique document

Patent documentation

Patent documentation 1: the spy opens the 2006-185576 communique

Summary of the invention

The problem that the invention desire solves

Yet,, pay structure in the optical path difference that has formed addition the 1st optical path difference function formation on the 2nd optical path difference function on the object lens in order to realize to exchange use to high density compact disc, DVD, CD according to disclosed technology in the patent documentation 1.But, when the 1st optical path difference function and the 2nd optical path difference function not being paid the addition of relation ground, final optical path difference is paid in the structure, shown in Figure 3 as patent documentation 1, and kick appears in the lowest point, calixconcavity appears in summit, structure becomes complicated, is difficult to constitute mould, and material is difficult for entering the mould depths during moulding, be difficult to moulding object lens optical surface transfer printing ideal form, be difficult to obtain the optical characteristics of being hoped.

The present invention considers the problems referred to above, the optical take-up apparatus that purpose is to provide a kind of object lens and adopts these object lens, in optical take-up apparatus and the object lens, though adopt simple lens as object lens, but also can carry out information record and/or regeneration definitely to high density compact disc (especially BD), 3 kinds of different dishes of recording density such as DVD, CD, wherein, object lens can be brought into play the optical characteristics of being hoped, prevent that simultaneously forming die structure from becoming too complicated, good transfer printing can be realized, simple structure and low cost can be realized.

With the means that solve problem

In order to solve above-mentioned problem, the invention of record is a kind of objective lens for optical pickup device in the 1st, in the described optical take-up apparatus, the 1st light beam of the wavelength X 1 (μ m) that penetrates with the 1st light source carries out the optically focused spot to the information recording surface of the 1st CD of protective seam with thickness t 1 and forms; (information recording surface of the 2nd CD of the protective seam of t1≤t2) carries out the optically focused spot and forms the 2nd light beam of the wavelength X 2 (λ 1＜λ 2) that penetrates with the 2nd light source to having thickness t 2; (information recording surface of the 3rd CD of the protective seam of t2＜t3) carries out the optically focused spot and forms the 3rd light beam of the wavelength X 3 (λ 2＜λ 3) that penetrates with the 3rd light source to having thickness t 3; Objective lens for optical pickup device is characterised in that,

On the optical surface of described object lens, form optical path difference and paid structure,

Described optical path difference is paid the 1st base configuration that structure is a flame-shaped structure and overlapping the forming of the 2nd base configuration of ladder configuration, when overlapping, makes the position consistency of the step of the position of all steps of described the 1st base configuration and described the 2nd base configuration,

Make L, M, when N is arbitrary integer, described the 1st light beam incides described optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that L diffraction light has maximum, described the 2nd light beam incides described optical path difference pays that M diffraction light has maximum diffraction light quantity in the diffraction light that takes place when textural, and described the 3rd light beam incides described optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that N diffraction light has maximum.

For example, when on exchanging, forming flame profile diffraction structure or stairstepping diffraction structure any with object lens, the combination of the diffraction number of times of the 1st light beam that diffraction efficiency is high, the 2nd light beam and the 3rd light beam is certain, so, there is the problem of design freedom decline.As described herein, by overlapping base configuration, can select diffraction number of times arbitrarily like this, design freedom improves, and can use single optical path difference function to design simultaneously, so design easily.And, make all step positions of described the 1st base configuration and the step position consistency of described the 2nd base configuration when overlapping, can simplify described optical path difference like this and pay structure, process the mould of object lens easily, resin and glass enter the mould depths easily during the object lens moulding, can improve manufacturing accuracy, can access light quantity, can reduce light loss near design load.

The object lens of the 2nd record are the inventions of record in the 1st, it is characterized in that, described the 2nd base configuration is 4 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(1.2λ1-0.4λ1)/(n-1)≤d1≤(1.2λ1+0.4λ1)/(n-1)

(1.25λ1-0.2λ1)/(n-1)≤d21≤(1.25λ1+0.2λ1)/(n-1)

(3.75λ1-0.2λ1)/(n-1)≤d22≤(3.75λ1+0.2λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

The object lens of the 3rd record are the inventions of record in the 1st or the 2nd, it is characterized in that, it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.95λ1-0.2λ1)/(n-1)≤d0≤(4.95λ1+0.2λ1)/(n-1)。

The object lens of the 4th record be the 1st to the 3rd any one in the invention of record, it is characterized in that, satisfy:

|L|＝2、M＝0、|N|＝1，

The sign symbol of L and N is different.

The object lens of the 5th record are the inventions of record in the 1st, it is characterized in that, described the 2nd base configuration is 6 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d21≤(1.2λ1+0.2λ1)/(n-1)

(6λ1-0.2λ1)/(n-1)≤d22≤(6λ1+0.2λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

The object lens of the 6th record are the inventions of record in the 1st or the 5th, it is characterized in that, it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(5λ1-0.2λ1)/(n-1)≤d0≤(5λ1+0.2λ1)/(n-1)。

The object lens of the 7th record are the inventions of record in the 1st, the 5th or the 6th, it is characterized in that, satisfy:

L＝0、|M|＝2、|N|＝3，

The sign symbol of M and N is identical.

The object lens of the 8th record are the inventions of record in the 1st, it is characterized in that, described the 2nd base configuration is 7 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.31λ1-0.2λ1)/(n-1)≤d21≤(1.31λ1+0.2λ1)/(n-1)

(7.86λ1-0.2λ1)/(n-1)≤d22≤(7.86λ1+0.2λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

The object lens of the 9th record are the inventions of record in the 1st or the 5th, it is characterized in that, it is the 7 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.86λ1-0.2λ1)/(n-1)≤d0≤(4.86λ1+0.2λ1)/(n-1)。

The object lens of the 10th record are the inventions of record in the 1st, the 8th or the 9th, it is characterized in that, satisfy:

|L|＝1、|M|＝3、|N|＝4，

The sign symbol of L, M, N is identical.

The object lens of the 11st record be the 1st to the 10th any one in the record invention, it is characterized in that,

The optical surface of described object lens has the ring-band shape middle section, the ring-band shape neighboring area that is formed on described its central area that contain optical axis at least, be formed on the neighboring area of ring-band shape around the described neighboring area,

Described the 1st light beam that passes described middle section and described neighboring area and described neighboring area is concentrated on the information recording surface of described the 1st CD,

Described the 2nd light beam that passes described middle section and described neighboring area is concentrated on the information recording surface of described the 2nd CD,

Described the 3rd light beam that passes described middle section is concentrated on the information recording surface of described the 3rd CD,

Described first optical path difference is paid structure and is arranged on the described middle section.

The optical take-up apparatus of the 12nd record wherein has object lens, and the 1st light beam of the wavelength X 1 (μ m) that these object lens penetrate with the 1st light source carries out the optically focused spot to the information recording surface of the 1st CD of protective seam with thickness t 1 and forms; (information recording surface of the 2nd CD of the protective seam of t1≤t2) carries out the optically focused spot and forms the 2nd light beam of the wavelength X 2 (λ 1＜λ 2) that penetrates with the 2nd light source to having thickness t 2; The 3rd light beam of the wavelength X 3 (λ 2＜λ 3) that penetrates with the 3rd light source to have thickness t 3 (information recording surface of the 3rd CD of the protective seam of t2＜t3) carries out the optically focused spot and forms, and optical take-up apparatus is characterised in that,

On the optical surface of described object lens, form first optical path difference and paid structure,

Described first optical path difference is paid the 1st base configuration that structure is a flame-shaped structure and overlapping the forming of the 2nd base configuration of ladder configuration, when overlapping, makes the position consistency of the step of the position of all steps of described the 1st base configuration and described the 2nd base configuration,

Make L, M, when N is arbitrary integer, described the 1st light beam incides described first optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that L diffraction light has maximum, described the 2nd light beam incides described first optical path difference pays that M diffraction light has maximum diffraction light quantity in the diffraction light that takes place when textural, and described the 3rd light beam incides described first optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that N diffraction light has maximum.

The optical take-up apparatus of the 13rd record is the invention of record in the 12nd, it is characterized in that, described the 2nd base configuration is 4 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(1.2λ1-0.4λ1)/(n-1)≤d1≤(1.2λ1+0.4λ1)/(n-1)

(1.25λ1-0.4λ1)/(n-1)≤d21≤(1.25λ1+0.4λ1)/(n-1)

(3.75λ1-0.4λ1)/(n-1)≤d22≤(3.75λ1+0.4λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

The optical take-up apparatus of the 14th record is the invention of record in the 12nd or the 13rd, it is characterized in that, it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.95λ1-0.4λ1)/(n-1)≤d0≤(4.95λ1+0.4λ1)/(n-1)

The optical take-up apparatus of the 15th record be the 12nd to the 14th any one in the invention of record, it is characterized in that, satisfy:

|L|＝2、M＝0、|N|＝1，

The sign symbol of L and N is different.

The optical take-up apparatus of the 16th record is the invention of record in the 12nd, it is characterized in that, described the 2nd base configuration is 6 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.2λ1-0.4λ1)/(n-1)≤d21≤(1.2λ1+0.4λ1)/(n-1)

(6λ1-0.4λ1)/(n-1)≤d22≤(6λ1+0.4λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

The optical take-up apparatus of the 17th record is the invention of record in the 12nd or the 16th, it is characterized in that, it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(5λ1-0.4λ1)/(n-1)≤d0≤(5λ1+0.4λ1)/(n-1)。

The optical take-up apparatus of the 18th record is the invention of record in the 12nd, the 16th or the 17th, it is characterized in that, satisfies:

L＝0、|M|＝2、|N|＝3，

The sign symbol of M, N is identical.

The optical take-up apparatus of the 19th record is the invention of record in the 12nd, it is characterized in that, described the 2nd base configuration is 7 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.31λ1-0.4λ1)/(n-1)≤d21≤(1.31λ1+0.4λ1)/(n-1)

(7.86λ1-0.4λ1)/(n-1)≤d22≤(7.86λ1+0.4λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

The optical take-up apparatus of the 20th record is the invention of record in the 12nd or the 19th, it is characterized in that, it is the 7 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.86λ1-0.4λ1)/(n-1)≤d0≤(4.86λ1+0.4λ1)/(n-1)。

The optical take-up apparatus of the 21st record is the invention of record in the 12nd, the 19th or the 20th, it is characterized in that, satisfies:

|L|＝1、|M|＝3、|N|＝4，

The sign symbol of L, M, N is identical.

The optical take-up apparatus of the 22nd record be the 12nd to the 21st any one in the record invention, it is characterized in that,

The optical surface of described object lens has the ring-band shape middle section, the ring-band shape neighboring area that is formed on described its central area that contain optical axis at least, be formed on the neighboring area of ring-band shape around the described neighboring area,

Described the 1st light beam that passes described middle section and described neighboring area and described neighboring area is concentrated on the information recording surface of described the 1st CD,

Described the 2nd light beam that passes described middle section and described neighboring area is concentrated on the information recording surface of described the 2nd CD,

Described the 3rd light beam that passes described middle section is concentrated on the information recording surface of described the 3rd CD,

Described first optical path difference is paid structure and is arranged on the described middle section.

The optical take-up apparatus of the 23rd record be the 12nd to the 22nd any one in the record invention, it is characterized in that, the imaging multiplying power m3 of the imaging multiplying power m1 of the described object lens when described the 1st light beam incides on the described object lens, the imaging multiplying power m2 of the described object lens when described the 2nd light beam incides on the described object lens, the described object lens when described the 3rd light beam incides on the described object lens, satisfy following formula (1), (2), (3) respectively:

-0.02＜m1＜0.02 (1)

-0.02＜m2＜0.02 (2)

-0.02＜m3＜0.02 (3)。

Optical take-up apparatus of the present invention has 3 light sources of the 1st light source, the 2nd light source, the 3rd light source at least.Optical take-up apparatus of the present invention further have be used for making the 1st beam condenser on the information recording surface of the 1st CD, make the 2nd beam condenser on the information recording surface of the 2nd CD, make the light-gathering optics of the 3rd beam condenser on the information recording surface of the 3rd CD.In addition, optical take-up apparatus of the present invention also has photo detector, is used for accepting the folded light beam of the information recording surface of the 1st CD, the 2nd CD or the 3rd CD.At this moment, preferred the 1st CD is that BD (Blu-ray Disc) or HD DVD (hereinafter referred to as HD), the 2nd CD are DVD, and preferred the 3rd CD is CD, but is not limited thereto.The 1st CD, the 2nd CD or the 3rd CD also can be the multiplayer optical disks with a plurality of information recording surfaces.

BD carries out the information recording/reproducing with the object lens of NA0.85, and the thickness of protective substrate is the 0.1mm degree.HD carries out the information recording/reproducing with the object lens of NA0.65 to 0.67, and the thickness of protective substrate is the 0.6mm degree.DVD be thickness that the object lens with NA0.60～0.67 degree carry out information recording/reproducing, protective substrate be the 0.6mm degree DVD series CD general name, comprise DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD+R, DVD+RW etc.In this instructions, CD is that the thickness that the object lens with NA0.45～0.53 degree carry out information recording/reproducing, protective substrate is the general name of the CD series CD of 1.2mm degree, comprises CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW etc.Recording density is that BD is the highest, below reduces in proper order by HD, DVD, CD.

The thickness t 1 of relevant protective substrate, t2, t3, the formula that preferably meets the following conditions (4), (5), (6), but be not limited thereto:

0.0750mm≤t1≤0.1125mm or

0.5mm≤t1≤0.7mm (4)

0.5mm≤t2≤0.7mm (5)

1.0mm≤t3≤1.3mm (6)。

In this instructions, the 1st light source, the 2nd light source, the 3rd light source be LASER Light Source preferably.Can preferably adopt semiconductor laser and silicon laser etc. as LASER Light Source.The 3rd wavelength X 3 (λ 3＞λ 2) formula that meets the following conditions (7), (8) of the 3rd light beam that the 2nd wavelength X 2 (λ 2＞λ 1) of the 2nd light beam that the 1st wavelength X the 1, the 2nd light source of the 1st light beam that preferred the 1st light source penetrates penetrates, the 3rd light source penetrate:

1.5×λ1＜λ2＜1.7×λ1 (7)

1.9×λ1＜λ3＜2.1×λ1 (8)。

Respectively with BD or HD, DVD and CD during as the 1st CD, the 2nd CD, the 3rd CD, the 1st wavelength X 1 of the 1st light source is preferably below 0.44 μ m more than the 0.35 μ m, more preferably below 0.415 μ m more than the 0.38 μ m, the 2nd wavelength X 2 of the 2nd light source is preferably below 0.68 μ m more than the 0.57 μ m, more preferably below 0.67 μ m more than the 0.63 μ m, the 3rd wavelength X 3 of the 3rd light source is preferably below 0.88 μ m more than the 0.75 μ m, more preferably below 0.82 μ m more than the 0.76 μ m.

In addition, can make at least 2 light source cellizations in the 1st light source, the 2nd light source, the 3rd light source.Blocking is meant that for example the 1st light source and the 2nd light source are fixed and is accommodated in 1 plug-in unit, but is not limited to this, broad sense then comprise 2 light sources be fixed on the aberration correction can not state.In addition, can also on light source, add and make also 1 plug-in unitization of aftermentioned photo detector.

As photo detector, preferably adopt photodetectors such as photodiode.The light that reflects on the information recording surface of CD incides photo detector, can obtain reading the signal that reads of recorded information on each CD with its output signal.And the light quantity that can detect the change of shape of the spot on the photo detector and change in location changes, and focuses on to detect and tracking detects, and detects according to this to make object lens move forward into line focusing and tracking.Photo detector also can be made up of a plurality of photodetectors.Photo detector also can have main photodetector and secondary photodetector.Photo detector can be the photodetector both sides of the key light for example used at the record regenerating of the receiving information photodetector of establishing 2 pairs, accept to follow the tracks of the secondary light of adjusting usefulness by the photodetector of these 2 pairs.Photo detector also can have and the corresponding a plurality of photo detectors of each light source.

Light-gathering optics has object lens.Light-gathering optics can have only object lens, but light-gathering optics also can also have coupled lens such as collimation lens except object lens.Coupled lens is meant the simple lens or the lens combination of the change beam divergence angle that is configured between object lens and the light source.Collimation lens is a kind of of coupled lens, is that the light that will incide collimation lens becomes the lens that directional light penetrates.Light-gathering optics and can have optical element such as diffraction optical element is used for the light beam that light source penetrates is divided into two side beams of usefulness such as main beam that the information record regenerating uses and tracking.In this instructions, object lens are meant the optical system with beam condenser function on the optical disc information record surface that light source is penetrated that is configured in facing on the CD position in optical take-up apparatus.Preferred object lens are meant the optical system with beam condenser function on the optical disc information record surface that light source is penetrated that is configured in facing on the CD position in optical take-up apparatus, and by gearing at least can be on optical axis direction the optical system of a displacement body.Object lens are single lens objective preferably, but also can be made of a plurality of optical elements.In addition, object lens can be glass lenss, also can be plastic lenss, or also can be to have established the hybrid lens that optical path difference is paid structure with light-cured resin etc. on glass lens.In addition, the plane of refraction of preferred object lens is aspheric surfaces.It is aspheric surface that also preferred object lens are established the basal surface that optical path difference pays structure.

In addition, when making object lens be glass lens, preferably use glass branchpoint Tg at the glass material below 400 ℃.By using glass branchpoint Tg, can die life can be prolonged like this with lower temperature moulding at the glass material below 400 ℃.As the low glass material of this glass branchpoint Tg, K-PG325, the K-PG375 (being name of product) of for example Sumita Optical Glass Co., Ltd.'s manufacturing arranged.

But, in general glass lens because proportion greater than resin lens, institute drives the burden increase of the driver of object lens so that object lens are the words weight of glass lens increases.Therefore, when making object lens be glass lens, preferably use the little glass material of proportion.Concrete preferred specific gravity is below 3.0, more preferably below 2.8.

In addition, when making object lens be plastic lens, the preferred cyclic polyolefin resinous materials of using, especially preferred following resin material in the cyclic polyolefin resinous materials: during 25 ℃ of temperature to the refractive index of wavelength 405nm in 1.52 to 1.60 scopes, in-5 ℃ to 70 ℃ temperature ranges, follow temperature variation to the variations in refractive index rate dN/dT of wavelength 405nm (℃ ^-1)-20 * 10 ^-5To-5 * 10 ^-5(more preferably-10 * 10 ^-5To-8 * 10 ^-5) in the scope.In addition, when making object lens be plastic lens, preferably make coupled lens also be plastic lens.

Below object lens are recorded and narrated.At least one optical surface of object lens has the neighboring area of middle section and its central area.At least one optical surface of object lens also can have neighboring area around the neighboring area.Preferred middle section is the zone that contains objective lens optical axis, but also can be the zone that does not contain.Preferred middle section, neighboring area and neighboring area are located on the same optical surface.As shown in Figure 1, to be provided in a side of and to be with the optical axis on the same optical surface be the concentric circles at center for preferred middle section CN, neighboring area MD, neighboring area OT.In addition, preferably on the middle section of object lens, establish the 1st optical path difference and pay structure.Can also on the neighboring area, establish the 2nd optical path difference and pay structure.When having neighboring area, neighboring area can be a plane of refraction, also can establish the 3rd optical path difference on neighboring area and pay structure.Preferred middle section, neighboring area, neighboring area be adjacency respectively, but between also can be slightly gapped.

Preferred the 1st optical path difference is paid structure and is located on the zone more than 70% of object lens middle section area, more preferably more than 90%.More preferably the 1st optical path difference pay structure be located at middle section comprehensively on.Preferred the 2nd optical path difference is paid structure and is located on the zone more than 70% of object lens neighboring area area, more preferably more than 90%.More preferably the 2nd optical path difference pay structure be located at the neighboring area comprehensively on.Preferred the 3rd optical path difference is paid structure and is located on the zone more than 70% of the neighboring area of object lens area, more preferably more than 90%.More preferably the 3rd optical path difference pay structure be located at neighboring area comprehensively on.

To pay structure be general name to the structure of incident beam additional optical path difference to so-called optical path difference in this instructions.Optical path difference is paid and is comprised also in the structure that the phase differential of paying phase differential pays structure.Phase differential is paid and is comprised diffraction structure in the structure.Optical path difference of the present invention is paid structure and be can be described as diffraction structure.Optical path difference is paid structure and is had step, preferably has a plurality of steps.By this step to incident beam additional optical path difference and/or phase differential.Paying the additional optical path difference of structure by optical path difference can be the integral multiple of incident beam wavelength, also can be the non-integral multiple of incident beam wavelength.Step can be held the configuration of periodic intervals ground on the optical axis vertical direction, also can hold the configuration of aperiodicity compartment of terrain on the optical axis vertical direction.

The preferred light path difference is paid structure, and to have with the optical axis be the endless belt of a plurality of concentric circles at center.Optical path difference is paid structure can get various cross sectional shapes (cross sectional shape that contains the face of optical axis).Especially it is that the overlapping cross sectional shape that contains optical axis is that the 1st base configuration of flame-shaped structure and the cross sectional shape that contains optical axis are the superimposed structure of the 2nd base configuration of ladder configuration that preferred the 1st optical path difference is paid structure.

The flame-shaped structure is shown in Fig. 2 (a) and (b), be meant and have optical path difference to pay the cross sectional shape that contains optical axis of the optical element of structure be saw-toothed shape, in other words, relatively the basal surface optical path difference is paid and is constructed that both out of plumb was also not parallel, and has the dip plane.In addition, ladder configuration is shown in Fig. 2 (c), be meant have optical path difference pay the cross sectional shape that contains optical axis of the optical element of structure be have a plurality of little step-like, in other words, optical path difference is paid the face that structure only is parallel to the face of basal surface and is parallel to optical axis, the face that does not have relative basal surface to tilt, be have a plurality of along with on the basal surface direction forward and the little structure that the length of optical axis direction changes gradually.In addition, when base configuration was ladder configuration, basal surface was the face with curvature, owing to light reflects on basal surface, so the phenomenon of the different refraction angle differences of the distance of leaving optical axis is arranged.Therefore, compare at the upper in-migration of the direction that is parallel to optical axis basal surface is got the situation of ladder configuration, preferably come basal surface is got ladder configuration at the identical optical length of light ray propagation direction top offset.In this instructions, " X is cut apart " is meant with the face of the ring-band shape of the optical axis vertical direction corresponding (relative) of 1 ladder configuration and distinguished by step, be divided into X, " small stair " is meant the step of optical axis direction minimum in 1 ladder configuration, and " big step " is meant the step of optical axis direction maximum in 1 ladder configuration.

When overlapping the 1st base configuration and the 2nd base configuration, preferred overlapping the 2nd base configuration that is different from the 1st base configuration on the 1st base configuration makes the position consistency of the step of the position of all steps of the 1st base configuration and the 2nd base configuration this moment.As preferred configuration, the deep-seated that makes the deep-seated of the flame-shaped structure shown in Fig. 3 (a) put the ladder configuration shown in P1 and Fig. 3 (b) is put P2 and is as one man carried out overlapping.Can obtain the 1st optical path difference shown in Fig. 3 (c) thus and pay structure.In this instructions,, be called the flame-shaped terrace structure with the overlapping flame-shaped structure in position consistency ground of the big step of this step position that makes flame-shaped and ladder configuration and the structure shown in Fig. 3 (c) that ladder configuration obtains.The flame-shaped terrace structure is that optical path difference is paid structure and had the face that favours basal surface and the face that is parallel to optical axis, be have a plurality of along with on the basal surface direction forward and the structure of the little structure that the length of optical axis direction changes gradually.And, can be to the endless belt of a plurality of units of overlapping the 2nd base configuration of endless belt of a unit of the 1st base configuration.In addition, the position of all step of the 2nd base configuration can be not and the position consistency of the step of the 1st base configuration.That is to say to have with the step position of the 1st base configuration inconsistent in the step of the 2nd base configuration.The 2nd optical path difference pay structure, the 3rd optical path difference pay structure can be overlapping also can not overlapping base configuration, can get the structure of the arbitrary shape shown in Fig. 2 and Fig. 3 this moment.

The preferred light path difference pays structure or base configuration is that certain unit shape is made structure periodically repeatedly.Here said " unit shape do periodically repeatedly " comprises also that certainly same shape is with one-period shape repeatedly.And the cycle unit shape of 1 unit is held the shape that cycle regularly is elongated gradually and shorten gradually, is also included among " the unit shape is done periodically repeatedly ".

Optical path difference is paid structure or base configuration and is had flame-shaped when structure, is that the zigzag shape of unit shape is made shape repeatedly.Can be that same zigzag shape is done repeatedly shown in Fig. 2 (a), also can shown in Fig. 2 (b) be along with on the basal surface direction forward and the size of zigzag shape becomes big shape or the shape that diminishes gradually.In addition, also can be the shape that the size of zigzag shape becomes the combination of shapes that the size of big shape and zigzag shape diminishes gradually gradually.But even the situation that the size of zigzag shape changes gradually, also preferred zigzag shape is almost constant in the size of optical axis direction (or light passes direction).In the flame-shaped structure, it is dark that the length of the optical axis direction of 1 zigzag shape (also can be the length of passing the radiation direction of zigzag shape) is called tooth pitch, and it is wide that the length of the optical axis vertical direction of 1 zigzag shape is called tooth pitch.Can also be following shape: be the shape that the step of flame-shaped structure is tossed about towards optical axis (center) in a certain zone, in other zones are the step of flame-shaped structure shapes towards optical axis (center), establish betwixt to be used for switching flame-shaped structure step towards necessary transition zone.This transition zone is the zone that is equivalent to optical path difference extreme value of a function point showing with the optical path difference function when paying the additional optical path difference of structure by optical path difference.The optical path difference function is held extreme point, and the slope of optical path difference function is little, so can relax the endless belt tooth pitch, can suppress optical path difference and pay the transmitance reduction that the structure form error causes.

Optical path difference is paid structure or base configuration when having ladder configuration, is that the stairstepping of unit shape is made shape repeatedly.Can get the identical little stairstepping of which floor (for example shown in Fig. 2 (c) 5 cut apart structure) shown in Fig. 2 (c) and make repeatedly shape etc.And, also can be along with on the basal surface direction forward and the size of ladder becomes the shape that the size of big shape and ladder diminishes gradually gradually, still, the length of preferred light direction of principal axis (or light passes direction) is almost constant.

Optical path difference is paid structure and is had scale-of-two shape shape shown in Fig. 2 (d) when (this structure claims that again 2 cut apart ladder configuration), can be along with on the basal surface direction forward and binary size becomes the shape that the size of big shape and ladder diminishes gradually gradually, but the length that preferred light passes direction is almost constant.

Subsequent with reference to Fig. 6～Figure 26, the example that various first optical path differences are paid structure is done and is described in more detail.L shown in the example, M, N, expression is incided first optical path difference with the 1st light beam, and to pay the diffraction diffraction of light number of times that has the maximum diffraction light quantity in the diffraction light that when structure take place be that to incide the diffraction diffraction of light number of times that has the maximum diffraction light quantity in the diffraction light that takes place when first optical path difference is paid structure be M time, the 3rd light beam integer L, M, the N when inciding first optical path difference and paying the diffraction diffraction of light number of times that has the maximum diffraction light quantity in the diffraction light of generation when constructing and be N time for L time, the 2nd light beam.

First optical path difference is paid structure example 1

In the example 1, the 2nd base configuration that is depicted as ladder configuration as Fig. 6 (b) is 4 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Fig. 6 (a) formula meets the following conditions:

(1.2λ1-0.4λ1)/(n-1)≤d1≤(1.2λ1+0.4λ1)/(n-1)

(1.25λ1-0.2λ1)/(n-1)≤d21≤(1.25λ1+0.2λ1)/(n-1)

(3.75λ1-0.2λ1)/(n-1)≤d22≤(3.75λ1+0.2λ1)/(n-1)。

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

We can say that following formula means that the step height d1 of the optical axis direction of the 1st base configuration is the step height that the 1st light beam wavelength λ 1 is provided 1.2 λ, 1 ± 0.4 λ, 1 optical path difference.The step height d21 that can also say the little optical axis direction that means the 2nd base configuration is the step height that the 1st light beam wavelength λ 1 is provided 1.25 λ, 1 ± 0.2 λ, 1 optical path difference, and the step height d22 of the big optical axis direction of the 2nd base configuration is the step height that the 1st light beam wavelength λ 1 is provided 3.75 λ, 1 ± 0.2 λ, 1 optical path difference.

The optical path difference of fireworks shape structure is paid in the structure as the 1st base configuration, and diffraction efficiency can be calculated according to the formula shown in following several 1.

[several 1]

Flame profile

${\mathrm{\η}}_m={\left[\frac{\sin \left(\mathrm{\π}({\mathrm{\αm}}_B-m)\right)}{\mathrm{\π}({\mathrm{\αm}}_B-m)}\right]}^2$ Wherein, $\mathrm{\α}=\frac{{\mathrm{\λ}}_B}{\mathrm{\λ}}\left[\frac{n\left(\mathrm{\λ}\right)-1}{n\left({\mathrm{\λ}}_B\right)-1}\right]$

η m: the diffraction efficiency of diffraction number of times m

λ: wavelength

N (λ): the refractive index during λ

M: diffraction number of times

λ B: reference wavelength (flame wavelength)

N (λ B): the refractive index during λ B

MB: the diffraction number of times of flameization

The step height d of the optical axis direction of step and the relation of diffraction number of times m can be represented with m=(n-1) d/ λ.

And in the ladder configuration as the 2nd base configuration, diffraction efficiency can be calculated according to the formula shown in following several 2.

[several 2]

Stairstepping

${\mathrm{\η}}_m={[\frac{\sin \mathrm{\π}\frac{m}{N}}{\mathrm{\πm}}\·\frac{\sin \mathrm{\π}(\mathrm{\β}-m)}{\sin \mathrm{\π}\frac{(\mathrm{\β}-m)}{N}}]}^2$ Wherein, $\mathrm{\β}=d\·N\·\frac{{\mathrm{\λ}}_B}{\mathrm{\λ}}\left[\frac{n\left(\mathrm{\λ}\right)-1}{n\left({\mathrm{\λ}}_B\right)-1}\right]$

η m: the diffraction efficiency of diffraction number of times m

λ: wavelength

N (λ): the refractive index during λ

M: diffraction number of times

λ B: the reference wavelength of phase-shifted

N (λ B): the refractive index during λ B

D: phase-shifted amount (unit: λ B)

N: ladder number (cutting apart number)

In this example, shown in Fig. 6 (a) and (b), make the 1st base configuration identical with being oriented of the 2nd base configuration overlapping towards carrying out." identical towards " is meant on the cross section that is containing objective lens optical axis, with the optical axis is the longitudinal axis, when being transverse axis with the optical axis vertical direction, the direction (bottom right falls or the lower-left falls) of the inclined-plane tendency of flame-shaped structure, the direction of being inclined to the enveloping surface inclined-plane of each layer of envelope ladder configuration is identical.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Fig. 6 (c), be the 4 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(4.95λ1-0.2λ1)/(n-1)≤d0≤(4.95λ1+0.2λ1)/(n-1)

(1.25λ1-0.2λ1)/(n-1)≤d00≤(1.25λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

We can say, following formula means that it is the step height that the 1st light beam wavelength λ 1 is provided 1.25 λ, 1 ± 0.2 λ, 1 optical path difference that the 1st optical path difference is paid the step height d00 of the little optical axis direction of structure, and the step height d0 that the 1st optical path difference is paid the big optical axis direction of structure is the step height that the 1st light beam wavelength λ 1 is provided 4.95 λ, 1 ± 0.2 λ, 1 optical path difference.

In this example, satisfy | L|=2, M=0, | N|=1, the sign symbol of L and N is different.Preferred L is for just.

Passing the 1st light beam that the 1st optical path difference pays structure, to leave the optical axis phase place more leading more and pass the 3rd light beam that the 1st optical path difference pays structure and leave the optical axis phase place more when backward more, perhaps passing the 1st light beam that the 1st optical path difference pays structure, to leave the optical axis phase place more backward more and pass the 3rd light beam that the 1st optical path difference pays structure and leave the optical axis phase place more when leading more, and the sign symbol that can be described as L and N is different.The 1st optical path difference is paid and is constructed when being the structure repeatedly of stairstepping, preferably in a stairstepping of unit structure, the leading and phase lag of above-mentioned phase place is arranged.

The 1st optical path difference of example 1 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 77%, the 2nd light beam at the 1st light beam and is about the 68%, the 3rd light beam and is about 57%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

Optical path difference is paid in the structure, and diffraction efficiency can be calculated according to the formula shown in following several 3.

[several 3]

General expression

F (x): the expression optical path difference is paid the function of constructing the phase differential that provides

First optical path difference is paid structure example 2

In the example 2, the 2nd base configuration that is depicted as ladder configuration as Fig. 7 (b) is 6 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Fig. 7 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d21≤(1.2λ1+0.2λ1)/(n-1)

(6λ1-0.2λ1)/(n-1)≤d22≤(6λ1+0.2λ1)/(n-1)。

In this example, shown in Fig. 7 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out." different towards " are meant on the cross section that is containing objective lens optical axis, with the optical axis is the longitudinal axis, when being transverse axis with the optical axis vertical direction, the direction (bottom right falls or the lower-left falls) of the inclined-plane tendency of flame-shaped structure, the direction of being inclined to the enveloping surface inclined-plane of each layer of envelope ladder configuration is opposite.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Fig. 7 (c), be the 6 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(5λ1-0.2λ1)/(n-1)≤d0≤(5λ1+0.2λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d00≤(1.2λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy L=0, | M|=2, | N|=3, the sign symbol of M, N is identical.Preferred M, N are for just.

Passing the 2nd light beam that the 1st optical path difference pays structure, to leave the optical axis phase place more leading more and to pass the 3rd light beam that the 1st optical path difference pays structure also be to leave the optical axis phase place more when leading more, perhaps passing the 2nd light beam that the 1st optical path difference pays structure, to leave the optical axis phase place more backward more and to pass the 3rd light beam that the 1st optical path difference pays structure also be to leave the optical axis phase place more when backward more, and the sign symbol that can be described as M and N is identical.The 1st optical path difference is paid and is constructed when being the structure repeatedly of stairstepping, preferably in a stairstepping of unit structure, the leading and phase lag of above-mentioned phase place is arranged.

The 1st optical path difference of example 2 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 80%, the 2nd light beam at the 1st light beam and is about the 62%, the 3rd light beam and is about 54%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 3

In the example 3, the 2nd base configuration that is depicted as ladder configuration as Fig. 8 (b) is 7 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Fig. 8 (a) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.31λ1-0.2λ1)/(n-1)≤d21≤(1.31λ1+0.2λ1)/(n-1)

(7.86λ1-0.2λ1)/(n-1)≤d22≤(7.86λ1+0.2λ1)/(n-1)。

In this example, shown in Fig. 8 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Fig. 8 (c), be the 7 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(4.86λ1-0.2λ1)/(n-1)≤d0≤(4.86λ1+0.2λ1)/(n-1)

(1.31λ1-0.2λ1)/(n-1)≤d00≤(1.31λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=3, | N|=4, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 3 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 69%, the 2nd light beam at the 1st light beam and is about the 65%, the 3rd light beam and is about 64%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 4

In the example 4, the 2nd base configuration that is depicted as ladder configuration as Fig. 9 (b) is 7 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Fig. 9 (a) formula meets the following conditions:

(4λ1-0.4λ1)/(n-1)≤d1≤(4λ1+0.4λ1)/(n-1)

(1.28λ1-0.2λ1)/(n-1)≤d21≤(1.28λ1+0.2λ1)/(n-1)

(7.68λ1-0.2λ1)/(n-1)≤d22≤(7.68λ1+0.2λ1)/(n-1)。

In this example, shown in Fig. 9 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Fig. 9 (c), be the 7 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(3.68λ1-0.2λ1)/(n-1)≤d0≤(3.68λ1+0.2λ1)/(n-1)

(1.28λ1-0.2λ1)/(n-1)≤d00≤(1.28λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=2, | M|=4, | N|=5, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 4 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 67%, the 2nd light beam at the 1st light beam and is about the 68%, the 3rd light beam and is about 60%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 5

In the example 5, the 2nd base configuration that is depicted as ladder configuration as Figure 10 (b) is 5 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 10 (a) formula meets the following conditions:

(2λ1-0.4λ1)/(n-1)≤d1≤(2λ1+0.4λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d21≤(1.2λ1+0.2λ1)/(n-1)

(4.8λ1-0.2λ1)/(n-1)≤d22≤(4.8λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 10 (a) and (b), make the 1st base configuration identical with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 10 (c), be the 5 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(6.8λ1-0.2λ1)/(n-1)≤d0≤(6.8λ1+0.2λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d00≤(1.2λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=3, M=0, | N|=1, the sign symbol difference of L, N.Preferred L is for just.

The 1st optical path difference of example 5 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 88%, the 2nd light beam at the 1st light beam and is about the 70%, the 3rd light beam and is about 57%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 6

In the example 6, the 2nd base configuration that is depicted as ladder configuration as Figure 11 (b) is 2 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 11 (a) formula meets the following conditions:

(4λ1-0.4λ1)/(n-1)≤d1≤(4λ1+0.4λ1)/(n-1)

(1.1λ1-0.2λ1)/(n-1)≤d21≤(1.1λ1+0.2λ1)/(n-1)

(1.1λ1-0.2λ1)/(n-1)≤d22≤(1.1λ1+0.2λ1)/(n-1)。

Here the situation (example 7,8,18,19 is also identical) that comprises d21=d22.

In this example, shown in Figure 11 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 11 (c), be the 2 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(2.9λ1-0.2λ1)/(n-1)≤d0≤(2.9λ1+0.2λ1)/(n-1)

(1.1λ1-0.2λ1)/(n-1)≤d00≤(1.1λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=4, M=3, | N|=3, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 6 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 97%, the 2nd light beam at the 1st light beam and is about the 74%, the 3rd light beam and is about 45%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 7

In the example 7, the 2nd base configuration that is depicted as ladder configuration as Figure 12 (b) is 2 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 12 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(2λ1-0.2λ1)/(n-1)≤d21≤(2λ1+0.2λ1)/(n-1)

(2λ1-0.2λ1)/(n-1)≤d22≤(2λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 12 (a) and (b), make the 1st base configuration identical with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 12 (c), be the 2 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(3λ1-0.2λ1)/(n-1)≤d0≤(3λ1+0.2λ1)/(n-1)

(2λ1-0.2λ1)/(n-1)≤d00≤(2λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=1, | N|=1, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 7 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 82%, the 2nd light beam at the 1st light beam and is about the 91%, the 3rd light beam and is about 57%.According to this example, can access than the high diffraction efficiency of flame-shaped structure.

First optical path difference is paid structure example 8

In the example 8, the 2nd base configuration that is depicted as ladder configuration as Figure 13 (b) is 2 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 13 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(3.1λ1-0.2λ1)/(n-1)≤d21≤(3.1λ1+0.2λ1)/(n-1)

(3.1λ1-0.2λ1)/(n-1)≤d22≤(3.1λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 13 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 13 (c), be the 2 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(3.1λ1-0.2λ1)/(n-1)≤d0≤(3.1λ1+0.2λ1)/(n-1)

(2.1λ1-0.2λ1)/(n-1)≤d00≤(2.1λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=1, | N|=1, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 8 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 90%, the 2nd light beam at the 1st light beam and is about the 85%, the 3rd light beam and is about 50%.According to this example, can access than the high diffraction efficiency of flame-shaped structure.

First optical path difference is paid structure example 9

In the example 9, the 2nd base configuration that is depicted as ladder configuration as Figure 14 (b) is 7 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 14 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.29λ1-0.2λ1)/(n-1)≤d21≤(1.29λ1+0.2λ1)/(n-1)

(7.74λ1-0.2λ1)/(n-1)≤d22≤(7.74λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 14 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 14 (c), be the 7 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(6.74λ1-0.2λ1)/(n-1)≤d0≤(6.74λ1+0.2λ1)/(n-1)

(1.29λ1-0.2λ1)/(n-1)≤d00≤(1.29λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=2, | N|=3, sign symbol is that the symbol of L is different with the symbol of M and N, M is identical with the symbol of N.Preferred L is for negative.

The 1st optical path difference of example 9 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 76%, the 2nd light beam at the 1st light beam and is about the 76%, the 3rd light beam and is about 64%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 10

In the example 10, the 2nd base configuration that is depicted as ladder configuration as Figure 15 (b) is 8 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 15 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.13λ1-0.2λ1)/(n-1)≤d21≤(1.13λ1+0.2λ1)/(n-1)

(7.91λ1-0.2λ1)/(n-1)≤d22≤(7.91λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 15 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 15 (c), be the 8 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(6.91λ1-0.2λ1)/(n-1)≤d0≤(6.91λ1+0.2λ1)/(n-1)

(1.13λ1-0.2λ1)/(n-1)≤d00≤(1.13λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=2, | M|=2, | N|=3, sign symbol is that the symbol of L is different with the symbol of M and N, M is identical with the symbol of N.Preferred L is for just.

The 1st optical path difference of example 10 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 95%, the 2nd light beam at the 1st light beam and is about the 70%, the 3rd light beam and is about 51%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 11

In the example 11, the 2nd base configuration that is depicted as ladder configuration as Figure 16 (b) is 8 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 16 (a) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.37λ1-0.2λ1)/(n-1)≤d21≤(1.37λ1+0.2λ1)/(n-1)

(9.59λ1-0.2λ1)/(n-1)≤d22≤(9.59λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 16 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 16 (c), be the 8 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(6.59λ1-0.2λ1)/(n-1)≤d0≤(6.59λ1+0.2λ1)/(n-1)

(1.37λ1-0.2λ1)/(n-1)≤d00≤(1.37λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy L=0, | M|=3, | N|=4, the sign symbol of M, N is identical.Preferred M, N are for just.

The 1st optical path difference of example 11 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 61%, the 2nd light beam at the 1st light beam and is about the 81%, the 3rd light beam and is about 71%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 12

In the example 12, the 2nd base configuration that is depicted as ladder configuration as Figure 17 (b) is 9 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 17 (a) formula meets the following conditions:

(2λ1-0.4λ1)/(n-1)≤d1≤(2λ1+0.4λ1)/(n-1)

(1.11λ1-0.2λ1)/(n-1)≤d21≤(1.11λ1+0.2λ1)/(n-1)

(8.88λ1-0.2λ1)/(n-1)≤d22≤(8.88λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 17 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 17 (c), be the 9 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(6.88λ1-0.2λ1)/(n-1)≤d0≤(6.88λ1+0.2λ1)/(n-1)

(1.11λ1-0.2λ1)/(n-1)≤d00≤(1.11λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=4, | N|=5, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 12 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 91%, the 2nd light beam at the 1st light beam and is about the 66%, the 3rd light beam and is about 48%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 13

In the example 13, the 2nd base configuration that is depicted as ladder configuration as Figure 18 (b) is 10 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 18 (a) formula meets the following conditions:

(2λ1-0.4λ1)/(n-1)≤d1≤(2λ1+0.4λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d21≤(1.2λ1+0.2λ1)/(n-1)

(10.8λ1-0.2λ1)/(n-1)≤d22≤(10.8λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 18 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 18 (c), be the 10 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(8.8λ1-0.2λ1)/(n-1)≤d0≤(8.8λ1+0.2λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d00≤(1.2λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=0, | M|=4, | N|=5, the sign symbol of M, N is identical.Preferred M, N are for just.

The 1st optical path difference of example 13 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 88%, the 2nd light beam at the 1st light beam and is about the 76%, the 3rd light beam and is about 57%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 14

In the example 14, the 2nd base configuration that is depicted as ladder configuration as Figure 19 (b) is 10 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 19 (a) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.33λ1-0.2λ1)/(n-1)≤d21≤(1.33λ1+0.2λ1)/(n-1)

(11.97λ1-0.2λ1)/(n-1)≤d22≤(11.97λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 19 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 19 (c), be the 10 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(8.97λ1-0.2λ1)/(n-1)≤d0≤(8.97λ1+0.2λ1)/(n-1)

(1.33λ1-0.2λ1)/(n-1)≤d00≤(1.33λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=0, | M|=4, | N|=5, the sign symbol of M, N is identical.Preferred M, N are for just.

The 1st optical path difference of example 14 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 74%, the 2nd light beam at the 1st light beam and is about the 85%, the 3rd light beam and is about 65%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 15

In the example 15, the 2nd base configuration that is depicted as ladder configuration as Figure 20 (b) is 6 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 20 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.19λ1-0.2λ1)/(n-1)≤d21≤(1.19λ1+0.2λ1)/(n-1)

(5.95λ1-0.2λ1)/(n-1)≤d22≤(5.95λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 20 (a) and (b), make the 1st base configuration identical with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 20 (c), be the 6 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(6.95λ1-0.2λ1)/(n-1)≤d0≤(6.95λ1+0.2λ1)/(n-1)

(1.19λ1-0.2λ1)/(n-1)≤d00≤(1.19λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=2, | M|=1, | N|=2, sign symbol is that the symbol of L is different with the symbol of M, N, the symbol of M, N is identical.Preferred L is for just.

The 1st optical path difference of example 15 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 86%, the 2nd light beam at the 1st light beam and is about the 74%, the 3rd light beam and is about 54%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 16

In the example 16, the 2nd base configuration that is depicted as ladder configuration as Figure 21 (b) is 4 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 21 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(3.25λ1-0.2λ1)/(n-1)≤d21≤(3.25λ1+0.2λ1)/(n-1)

(9.75λ1-0.2λ1)/(n-1)≤d22≤(9.75λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 21 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 21 (c), be the 4 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(8.75λ1-0.2λ1)/(n-1)≤d0≤(8.75λ1+0.2λ1)/(n-1)

(3.25λ1-0.2λ1)/(n-1)≤d00≤(3.25λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=0, | M|=1, | N|=2, the sign symbol of M, N is identical.Preferred M, N are for just.

The 1st optical path difference of example 16 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 81%, the 2nd light beam at the 1st light beam and is about the 89%, the 3rd light beam and is about 61%.According to this example, can access the high diffraction efficiency of rate of exchange trapezoidal configuration.

First optical path difference is paid structure example 17

In the example 17, the 2nd base configuration that is depicted as ladder configuration as Figure 22 (b) is 4 ladder configuration of cutting apart.The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 22 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(3.22λ1-0.2λ1)/(n-1)≤d21≤(3.22λ1+0.2λ1)/(n-1)

(9.66λ1-0.2λ1)/(n-1)≤d22≤(9.66λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 22 (a) and (b), make the 1st base configuration identical with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 22 (c), be the 4 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(10.66λ1-0.2λ1)/(n-1)≤d0≤(10.66λ1+0.2λ1)/(n-1)

(3.22λ1-0.2λ1)/(n-1)≤d00≤(3.22λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=2, | M|=0, | N|=1, the sign symbol difference of L, N.Preferred L is for just.

The 1st optical path difference of example 17 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 78%, the 2nd light beam at the 1st light beam and is about the 72%, the 3rd light beam and is about 58%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 18

In the example 18, the 2nd base configuration that is depicted as ladder configuration as Figure 23 (b) is 2 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 23 (a) formula meets the following conditions:

(2λ1-0.4λ1)/(n-1)≤d1≤(2λ1+0.4λ1)/(n-1)

(3.05λ1-0.2λ1)/(n-1)≤d21≤(3.05λ1+0.2λ1)/(n-1)

(3.05λ1-0.2λ1)/(n-1)≤d22≤(3.05λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 23 (a) and (b), make the 1st base configuration identical with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 23 (c), be the 2 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(5.05λ1-0.2λ1)/(n-1)≤d0≤(5.05λ1+0.2λ1)/(n-1)

(3.05λ1-0.2λ1)/(n-1)≤d00≤(3.05λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=2, | M|=1, | N|=0, the sign symbol of L, M is identical.Preferred L, M are for just.

The 1st optical path difference of example 18 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 98%, the 2nd light beam at the 1st light beam and is about the 91%, the 3rd light beam and is about 41%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

First optical path difference is paid structure example 19

In the example 19, the 2nd base configuration that is depicted as ladder configuration as Figure 24 (b) is 2 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 24 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(5λ1-0.2λ1)/(n-1)≤d21≤(5λ1+0.2λ1)/(n-1)

(5λ1-0.2λ1)/(n-1)≤d22≤(5λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 24 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 24 (c), be the 2 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(5λ1-0.2λ1)/(n-1)≤d0≤(5λ1+0.2λ1)/(n-1)

(4λ1-0.2λ1)/(n-1)≤d00≤(4λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=1, | N|=0, the sign symbol of L, M is identical.Preferred L, M are for just.

The 1st optical path difference of example 19 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 82%, the 2nd light beam at the 1st light beam and is about the 83%, the 3rd light beam and is about 54%.According to this example, can access the diffraction efficiency higher than ladder configuration.

First optical path difference is paid structure example 20

In the example 20, the 2nd base configuration that is depicted as ladder configuration as Figure 25 (b) is 3 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 25 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(2λ1-0.2λ1)/(n-1)≤d21≤(2λ1+0.2λ1)/(n-1)

(4λ1-0.2λ1)/(n-1)≤d22≤(4λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 25 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 25 (c), be the 3 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(3λ1-0.2λ1)/(n-1)≤d0≤(3λ1+0.2λ1)/(n-1)

(2λ1-0.2λ1)/(n-1)≤d00≤(2λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=0, | N|=1, the sign symbol of L, N is identical.Preferred L, N are for just.

The 1st optical path difference of example 20 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 100%, the 2nd light beam at the 1st light beam and is about the 88%, the 3rd light beam and is about 44%.According to this example, can access the diffraction efficiency higher than ladder configuration.

First optical path difference is paid structure example 21

In the example 21, the 2nd base configuration that is depicted as ladder configuration as Figure 26 (b) is 3 ladder configuration of cutting apart (scale-of-two structures).The length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of the 2nd base configuration (μ m), the 2nd base configuration and be depicted as the length d 1 (μ m) of optical axis direction of step of the 1st base configuration of flame-shaped structure as Figure 26 (a) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(3λ1-0.2λ1)/(n-1)≤d21≤(3λ1+0.2λ1)/(n-1)

(6λ1-0.2λ1)/(n-1)≤d22≤(6λ1+0.2λ1)/(n-1)。

In this example, shown in Figure 26 (a) and (b), make the 1st base configuration different with being oriented of the 2nd base configuration overlapping towards carrying out.

First optical path difference that overlapping the 1st base configuration and the 2nd base configuration obtain is paid structure shown in Figure 26 (c), be the 3 flame ladder configuration of cutting apart, first optical path difference is paid the length d 00 (μ m) of optical axis direction of the length d 0 (μ m) of optical axis direction of the maximum step of structure and the small stair that first optical path difference is paid structure, and formula meets the following conditions:

(5λ1-0.2λ1)/(n-1)≤d0≤(5λ1+0.2λ1)/(n-1)

(3λ1-0.2λ1)/(n-1)≤d00≤(3λ1+0.2λ1)/(n-1)。

More preferably the 1st optical path difference of middle section is paid all step of structure height d0, d00 and is satisfied above-mentioned conditional, but, step away from optical axis must be a step height of having considered object lens aspherical shape curved surface, the step height d0, the d00 that leave the step of optical axis have the tendency that becomes big gradually, have the step that is slightly larger than above-mentioned conditional sometimes.Therefore, preferred the 1st optical path difference is paid structure and is satisfied above-mentioned conditional at least near the d0 and the d00 of optical axis.

In this example, satisfy | L|=1, | M|=1, | N|=2, the sign symbol of L, M, N is identical.Preferred L, M, N are for just.

The 1st optical path difference of example 21 is paid in the structure, and the diffraction efficiency when the 3rd wavelength that the 2nd wavelength that can make the 1st wavelength of the 1st light beam be about 405nm, the 2nd light beam is about 655nm, the 3rd light beam is about 785nm is about the 100%, the 2nd light beam at the 1st light beam and is about the 80%, the 3rd light beam and is about 40%.According to this example, can make the number of times that in the diffraction structure of common flame-shaped structure and ladder configuration, can not obtain be maximum diffraction efficiency.

On the middle section of object lens, establish the 1st optical path difference and pay structure, and on the neighboring area of object lens, establish the 2nd optical path difference and pay when constructing, can be located on the different optical surface of object lens, but preferably be located on the same optical surface.So the eccentric error in the time of can reducing manufacturing on the same optical surface by being located at is preferred.In addition, compare on the face that is located at object lens CD side, preferred the 1st optical path difference pay the structure and the 2nd optical path difference pay the structure be located on the face of object lens light source side.

Object lens make and pass object lens and be provided with the 1st optical path difference and pay the 1st light beam of the middle section of structure, the 2nd light beam and the 3rd light beam and form optically focused spot ground optically focused respectively.Preferred object lens make pass object lens be provided with the 1st optical path difference pay the 1st light beam of the middle section of structure can the information record and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 1st CD.In addition, object lens make pass object lens be provided with the 1st optical path difference pay the 2nd light beam of the middle section of structure can information record and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 2nd CD.And, object lens make pass object lens be provided with the 1st optical path difference pay the 3rd light beam of the middle section of structure can information record and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 3rd CD.In addition; the thickness t 1 of the 1st CD protecting substrate and the thickness t 2 of the 2nd CD protecting substrate are not simultaneously; preferred the 1st optical path difference is paid the 1st light beam and the 2nd light beam that structure is paid structure to passing the 1st optical path difference; revise owing to the thickness t 1 of the 1st CD protecting substrate and the thickness t 2 different spherical aberrations that produce of the 2nd CD protecting substrate, and/or the spherical aberration that produces owing to the 1st light beam is different with the wavelength of the 2nd light beam.And; preferred the 1st optical path difference is paid the 1st light beam and the 3rd light beam that structure is paid structure to passing the 1st optical path difference; revise owing to the thickness t 1 of the 1st CD protecting substrate and the thickness t 3 different spherical aberrations that produce of the 3rd CD protecting substrate, and/or the spherical aberration that produces owing to the 1st light beam is different with the wavelength of the 3rd light beam.

When the focal length during at the 1st light beam is the center thickness of f1 (mm), object lens when being d (mm) with object lens, preferably satisfy following formula (7):

0.7≤d/f1≤2.0 (7)。

More preferably satisfy following formula (7) ':

1.0≤d/f1≤1.5 (7)’。

By said structure, can not reduce optical path difference and pay the tooth pitch ground of structure and guarantee the manufacturing of object lens is become operating distance as the CD of the 3rd CD easily, and can keep high light utilization ratio.

In addition, the formula that preferably meets the following conditions:

2.1mm≤Φ≤4.2mm。

The effective diameter of object lens when Φ represents the use of the 1st CD.By satisfying above-mentioned scope, the operating distance as the CD of the 3rd CD can be guaranteed no problem distance on reality is used, simultaneously, be plastic lens even for example make object lens, the aberration in the time of also can be with temperature variation changes the unchallenged degree that maintains.

Object lens are provided with the 2nd optical path difference and pay when constructing, and object lens make the 1st light beam and the 2nd light beam that pass the neighboring area form optically focused spot ground optically focused respectively with it.Preferred object lens make and pass object lens and be provided with the 1st light beam that the 2nd optical path difference is paid the neighboring area of structure, can the information record and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 1st CD.In addition, object lens are provided with the 2nd optical path difference and pay when structure, and object lens make the 2nd light beam that passes the neighboring area with it, can the information record and/or again the dried rhizome of rehmannia be concentrated on the information recording surface of the 2nd CD.In addition, preferred the 2nd optical path difference is paid structure and is revised owing to pass the chromosphere surface aberrations that the wavelength difference of the 1st light beam that the 2nd optical path difference pays structure and the 2nd light beam causes generation.

As preferred configuration, can enumerate the 3rd light beam that passes the neighboring area and be not used in the record of the 3rd CD and/or the form of regeneration.Preferably make the 3rd light beam that passes the neighboring area on the 3rd optical disc information record surface, forming the not contribution of optically focused spot.That is to say that object lens are provided with the 2nd optical path difference and pay when constructing, and preferably make the 3rd light beam that passes the neighboring area form hot spot on the information recording surface of the 3rd CD by it.As shown in Figure 4, preferably pass in the spot that the 3rd light beam of object lens forms on the information recording surface of the 3rd CD, outside from optical axis (or spot central part), have spot pars intermedia SMD, the light quantity density that the high spot central part SCN of light quantity density, light quantity density be lower than the spot central part successively and be higher than the spot periphery SOT that the spot pars intermedia is lower than the spot central part.The spot central part is used for the information record and/or the regeneration of CD, and spot pars intermedia and spot periphery are not used in the information record and/or the regeneration of CD.In the above-mentioned situation, claim that this spot periphery is a hot spot.That is to say, preferably pass the 3rd light beam that the 2nd optical path difference that is located on the object lens neighboring area is paid structure, on the information recording surface of the 3rd CD, form the spot periphery.But also might not be aforesaid hot spot, the pars intermedia but the high spot central part of light quantity density is speckless on every side has only light quantity density to be lower than the spot periphery of spot central part, at this moment, claims that this spot periphery is a hot spot.The optically focused spot or the spot of said here the 3rd light beam, the preferably spot on the 1st pinpointed focus.

Preferred configuration when having neighboring area can enumerate that the 1st light beam that passes neighboring area is used for the record and/or the regeneration of the 1st CD, the 2nd light beam and the 3rd light beam that passes neighboring area is not used in the record of the 2nd CD and the 3rd CD and/or the form of regeneration.Preferably make the 2nd light beam that passes neighboring area and the 3rd light beam respectively on the information recording surface of the 2nd CD and the 3rd CD, forming the not contribution of optically focused spot.That is to say that when object lens had neighboring area, the 2nd light beam and the 3rd light beam that preferably pass the neighboring area of object lens formed hot spot on the information recording surface of the 2nd CD and the 3rd CD.In other words, the 2nd light beam and the 3rd light beam that preferably passes the neighboring area of object lens forms the spot periphery on the information recording surface of the 2nd CD and the 3rd CD.

Neighboring area has the 3rd optical path difference when paying structure, also can make the 3rd optical path difference pay that structure changes slightly to the wavelength that passes the 3rd optical path difference and pay the 1st light beam modifying factor the 1st light source of structure and the chromosphere surface aberration that produces.Wavelength change slightly be meant ± 10nm is with interior change.For example the 1st light beam is when wavelength X 1 generation ± 5nm changes, preferably pay the spherical aberration that the 1st light beam of neighboring area is passed in structure compensation by the 3rd optical path difference, the variable quantity that makes the wavefront aberration on the 1st optical disc information record surface is below 0.070 λ 2rms more than the 0.001 λ 2rms.

It can be single ladder configuration and single flame-shaped structure that the 2nd optical path difference is paid structure, also can be the structure of overlapping flame-shaped structure and thick (tooth pitch is big) flame-shaped structure.The 2nd optical path difference is paid and is constructed when being this superimposed structure, can make this flame-shaped structure (when the 2nd optical path difference is paid structure, non-thick (tooth pitch is little) diffraction structure) to the suitable optical path difference of the 1st wavelength X 1 even-multiple that the 1st light beam is paid the 1st light beam, the phase place of the 1st light beam wave front is not changed.And when the 3rd wavelength X 3 of the 3rd light beam was the wavelength of almost even-multiple of the 1st wavelength of the 1st light beam, by paying the optical path difference of the 3rd light beam integral multiple, the phase place of same the 3rd light beam wave front did not change.Above-mentioned formation has the advantage that this diffraction structure does not influence the 1st light beam and the 3rd beam condenser.When even-multiple quite is meant and is natural number with n, (2n-0.1) * λ (2n+0.1) * λ scope below 1 more than 1.

Form the 1st optical path difference and pay structure by overlapping the 1st base configuration and the 2nd base configuration, can make the emergent light direction of the 1st light beam that passes the 1st optical path difference and pay structure, the 2nd light beam, the 3rd light beam all different, so, even the 1st light beam, the 2nd light beam, the 3rd light beam all incide on the object lens with identical imaging multiplying power (for example all being directional light), also can revise the aberration that adopts different types of CD and cause generation, can exchange.

When object lens are plastic lens, also can pay structure as the 1st optical path difference with on the 1st base configuration and the 2nd base configuration, using the structure of further overlapping the 3rd base configuration of structure as the temperature characterisitic correction.But the 1st CD is HD, because influence of temperature variation is very not big, so, also can on object lens, not establish as the base configuration of temperature characterisitic correction with structure.The step height of the optical axis direction of concrete preferred the 3rd base configuration, be to the 1st light beam provide the 1st wavelength summary 10 wavelength branch optical path differences, the 2nd light beam is provided the summary 6 wavelength branch optical path differences of the 2nd wavelength, the 3rd light beam is provided the step height of the summary 5 wavelength branch optical path differences of the 3rd wavelength.

When object lens are plastic lens, also can with as the temperature characterisitic correction with tectonic stacking the structure of base configuration, pay structure as the 2nd optical path difference.But the 1st CD is HD, because influence of temperature variation is very not big, so, also can on object lens, not establish as the base configuration of temperature characterisitic correction with structure.The step height of the optical axis direction of concrete preferred the 3rd base configuration, be to the 1st light beam provide the 1st wavelength summary 5 wavelength branch optical path differences, the 2nd light beam is provided the summary 3 wavelength branch optical path differences of the 2nd wavelength, the 3rd light beam is provided the step height of the summary 2 wavelength branch optical path differences of the 3rd wavelength.

When being provided with neighboring area and object lens and being plastic lens, preferably further establish the 3rd optical path difference on neighboring area and pay structure, at this moment, it can be the structure that has the 3rd base configuration at least that the 3rd optical path difference is paid structure.

As mentioned above, preferred step height is within reason big.It is that the step of the base configuration that obtains of overlapping a plurality of base configuration and this optical path difference certain endless belt of paying structure is when just being higher than reference value that optical path difference is paid structure, just reduce by 10 λ B/ (n-1) (μ m) by the step that makes endless belt, can avoid influencing optical property, reduce too big step height.As reference value, can set arbitrarily, but the preferred reference value is 10 λ B/ (n-1) (μ m).

In addition, from making the few viewpoint of preferred elongated endless belt, preferred the 1st optical path difference is paid the value of all endless belt of structure (step height/tooth pitch is wide) below 1, more preferably below 0.8.More preferably all optical path differences are paid the value of all endless belt (step height/tooth pitch is wide) of structure below 1, more preferably below 0.8.

With the thing image side numerical aperture that the 1st optical disc reproducing and/or needed for record information are wanted be NA1, thing image side numerical aperture that the 2nd optical disc reproducing and/or needed for record information are wanted is that (NA1 〉=NA2), the thing image side numerical aperture that the 3rd optical disc reproducing and/or needed for record information are wanted are NA3 (NA2＞NA3) to NA2.Preferred NA1 is more than 0.6 below 0.9.Especially preferred NA1 is 0.85.Preferred NA2 is more than 0.55 below 0.7.Especially preferred NA2 is 0.60 or 0.65.Preferred NA3 is more than 0.4 below 0.55.Especially preferred NA3 is 0.45 or 0.53.

The boundary of preferred object lens middle section and neighboring area is formed on the part of the above 1.2NA3 of 0.9NA3 following (more preferably 0.95NA3 is above, 1.15NA3 the is following) scope when being equivalent to the use of the 3rd light beam.More preferably the boundary of object lens middle section and neighboring area is formed on the part that is equivalent to NA3.On the part of the above 1.2NA2 of 0.9NA2 following (more preferably below the above 1.15NA2 of the 0.95NA2) scope the when boundary of preferred object lens neighboring area and neighboring area is formed on and is equivalent to the 2nd light beam and uses.More preferably the object lens neighboring area is formed on the part that is equivalent to NA2 with the boundary of neighboring area.

When the 3rd beam condenser that passes object lens was on the information recording surface of the 3rd CD, the preferred spheres surface aberration had the discontinuous portion in 1 place at least.In the above 1.2NA3 of 0.9NA3 when at this moment, preferred discontinuous portion exists in the use of the 3rd light beam following (more preferably the above 1.15NA3 of 0.95NA3 is following) scope.

In addition, the 3rd beam condenser that will pass object lens when spherical aberration does not continuously have discontinuous is on the information recording surface of the 3rd CD the time, the absolute value that also preferred NA2 goes up longitudinal spherical aberration at the absolute value of longitudinal spherical aberration more than the 0.03 μ m, on the NA3 below 0.02 μ m.More preferably the NA2 absolute value of going up longitudinal spherical aberration at the absolute value of longitudinal spherical aberration more than the 0.08 μ m, on the NA3 below 0.01 μ m.

In addition, can suitably set the diffraction efficiency of middle section according to the purposes of optical take-up apparatus to each wavelength.For example, the 1st CD is write down and during the optical take-up apparatus of regenerating, the 2nd and the 3rd CD only being regenerated, preferably pay attention to the diffraction efficiency that middle section and/or neighboring area are set in the 1st light beam ground.And the 1st CD is only regenerated, the 2nd and the 3rd CD is write down and during the optical take-up apparatus of regenerating, preferably payes attention to the diffraction efficiency that the 2nd and the 3rd light beam ground is set the diffraction efficiency of middle section, paid attention to setting neighboring area, the 2nd light beam ground.

Any occasion can both be guaranteed the diffraction efficiency of high the 1st light beam that is calculated by each regional area hamming by the formula of meeting the following conditions (9).

n11≤η21 (9)

Wherein, η 11 expressions the 1st light beam is in the diffraction efficiency of middle section, and η 21 expressions the 1st light beam is in the diffraction efficiency of neighboring area.The diffraction efficiency of middle section is when paying attention to the 2nd, the 3rd wavelength light beam, though the diffraction efficiency of the 1st light beam reduces on the middle section, but the numerical aperture of the 1st CD is during greater than the numerical aperture of the 3rd CD, consider the whole effective diameter of the 1st light beam, the diffraction efficiency of middle section reduces not very big influence.

Diffraction efficiency in this instructions can be defined as follows.

(1) divide middle section and neighboring area, measure with same material form have same focal point distance, lens thickness, a numerical aperture do not form the transmitance that the 1st and the 2nd optical path difference is paid the object lens of structure.The light beam on the neighboring area is incided in blocking when measuring the transmitance of middle section, and the light beam on the middle section is incided in blocking when measuring the transmitance of neighboring area.

(2) divide middle section and neighboring area, measure and have the transmitance that the 1st and the 2nd optical path difference is paid the object lens of structure.

(3) remove the result of above-mentioned (2) with the result of (1), with remove value be each regional diffraction efficiency.

In addition, can make the 1st light beam to the 3 light beams any two light beams the light utilization ratio more than 70%, the light utilization ratio of a remaining light beam is more than 30% below 70%.The light utilization ratio that also can make a remaining light beam is more than 40% below 60%.At this moment, preferably making the light utilization ratio is the 3rd light beam at the light beam of (or more than 40% below 60%) more than 30% below 70%.

Calculating of the light utilization ratio here is as follows: to have formed the light quantity that the 1st optical path difference pays in the airy's disk of the optically focused spot that the object lens of structure (also can form the 2nd optical path difference is paid structure and the 3rd optical path difference is paid structure) form on the information recording surface of CD is A, has a same focal point distance with what form with same material, thickness on the axle, numerical aperture, the 1st optical path difference that do not form of wavefront aberration is paid structure, the 2nd optical path difference is paid light quantity in structure and the 3rd optical path difference pay the optically focused spot that the object lens of structure form on the information recording surface of optical information recording medium the airy's disk when being B, is calculated by A/B.Here said airy's disk is that the optical axis with the optically focused spot is the circle of radius centered r '.Use r '=0.61 λ/NA to represent.

The 1st light beam, the 2nd light beam and the 3rd light beam can be used as directional light and incide on the object lens, also can be used as diverging light or restrain light to incide on the object lens.The imaging multiplying power m1 of object lens satisfied following formula (1) when preferred the 1st light beam incided on the object lens:

-0.02＜m1＜0.02 (1)。

And make the 1st light beam is diverging light when inciding on the object lens, when preferred the 1st light beam incides on the object lens imaging multiplying power m1 of object lens satisfy following formula (1 '):

-0.10＜m1＜0(1‘)。

In addition, making the 2nd light beam is directional light or when slightly directional light incided on the object lens, the imaging multiplying power m2 of object lens satisfied following formula (2) when preferred the 2nd light beam incided on the object lens:

-0.02＜m2＜0.02 (2)。

And make the 2nd light beam is diverging light when inciding on the object lens, when preferred the 2nd light beam incides on the object lens imaging multiplying power m2 of object lens satisfy following formula (2 '):

-0.10＜m2＜0(2‘)。

In addition, making the 3rd light beam is directional light or when slightly directional light incided on the object lens, the imaging multiplying power m3 of object lens satisfied following formula (3) when preferred the 3rd light beam incided on the object lens.When the 3rd light beam is directional light, easy generation problem during tracking, even but the present invention realizes the 3rd light beam is directional light, also can access better tracking, and can write down definitely and/or regenerate 3 kinds of different CDs.

-0.02＜m3＜0.02 (3)。

And make the 3rd light beam is diverging light when inciding on the object lens, when preferred the 3rd light beam incides on the object lens imaging multiplying power m3 of object lens satisfy following formula (3 '):

-0.10＜m3＜0(3‘)。

The operating distance of object lens (WD) is better below the above 1.5mm of 0.20mm when in addition, using the 3rd CD.Preferably below the above 1.20mm of 0.3mm.The WD of object lens is better below the above 1.3mm of 0.4mm when using the 2nd CD.The WD of object lens is better below the above 1.2mm of 0.4mm when using the 1st CD.

The optical information recording regenerator that the present invention relates to has optical disc apparatus, has above-mentioned optical take-up apparatus in this optical disc apparatus.

The optical disc apparatus of equipping in the optical information recording regenerator is explained, and optical disc apparatus has following manner: have only the dish that carries and can supporting CD, take out to the outside from the optical information recording regenerator body of taking in optical take-up apparatus etc.; Take out to the outside together with the optical drive drive unit body of taking in optical take-up apparatus etc.

Adopt in the optical information recording regenerator of above-mentioned each mode, roughly equip following component parts, but be not limited thereto.

Be accommodated in the optical take-up apparatus in shell etc.; Make the drive source of the optical take-up apparatus such as search motor that optical take-up apparatus week or periphery in CD move together with shell; Have to the optical take-up apparatus of the interior week of CD or the guided way of periphery direct light pick device shell etc. and transfer means; Carry out the Spindle Motor of CD rotation driving etc.

In the former mode, except above-mentioned each component parts, also be provided with the dish that carries and can supporting CD and be used for making loader mechanism that dish slides etc., not dish and loader mechanism in latter's mode are preferably established the drawer that is equivalent to the fuselage base from each component parts to the outside that can pull out.

The effect of invention

According to the present invention, can provide a kind of object lens machine to adopt the optical take-up apparatus of these object lens, wherein, can bring into play the optical characteristics of being hoped, simultaneously, prevent that forming die structure from becoming complicated, well transfer printing can realize simplification, the low cost of its structure.

Description of drawings

Fig. 1: be the figure that object lens OBJ one example of the present invention is seen from optical axis direction (a), (b) be sectional view.

Fig. 2: the optical path difference that object lens OBJ of the present invention is provided with is paid the model utility schematic cross-section of several examples (a)～(d) of structure.

Fig. 3: optical path difference is paid the synoptic diagram of tectonic stacking.

Fig. 4: the shape synoptic diagram of the optically focused spot of object lens of the present invention.

Fig. 5: the structure generalized schematic of optical take-up apparatus of the present invention.

Fig. 6: the optical path difference of example 1 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Fig. 7: the optical path difference of example 2 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Fig. 8: the optical path difference of example 3 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Fig. 9: the optical path difference of example 4 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 10: the optical path difference of example 5 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 11: the optical path difference of example 6 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 12: the optical path difference of example 7 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 13: the optical path difference of example 8 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 14: the optical path difference of example 9 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 15: the optical path difference of example 10 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 16: the optical path difference of example 11 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 17: the optical path difference of example 12 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 18: the optical path difference of example 13 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 19: the optical path difference of example 14 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 20: the optical path difference of example 15 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 21: the optical path difference of example 16 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 22: the optical path difference of example 17 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 23: the optical path difference of example 18 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 24: the optical path difference of example 19 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 25: the optical path difference of example 20 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Figure 26: the optical path difference of example 21 is paid in the structure, (a) schematic cross-section of the 1st base configuration, and (b) schematic cross-section of the 2nd base configuration, (c) overlapping optical path difference is paid the schematic cross-section of structure.

Symbol description

AC two shaft drives

PPS dichroism prism

The CL collimation lens

LD1 bluish violet semiconductor laser

The LM laser module

The OBJ object lens

The PL1 protective substrate

The PL2 protective substrate

The PL3 protective substrate

The PU1 optical take-up apparatus

The RL1 information recording surface

The RL2 information recording surface

The RL3 information recording surface

The CN middle section

The MD neighboring area

The neighboring area of OT

Embodiment

Embodiments of the present invention are described with reference to the accompanying drawings.Fig. 5 is the structure generalized schematic that can carry out the present embodiment optical take-up apparatus PU1 of information record and/or regeneration to different discs BD, DVD, CD definitely.This optical take-up apparatus PU1 can carry in optical information recording regenerator.Here be that the 1st CD, DVD are that the 2nd CD, CD are the 3rd CD with BD.The present invention is not limited to present embodiment.

Optical take-up apparatus PU1 has object lens OBJ, diaphragm ST, collimation lens CL, dichroism prism PPS, when BD is carried out the information recording/reproducing luminous ejaculation wavelength X 1=405nm laser beam (the 1st light beam) the 1st semiconductor laser LD1 (the 1st light source) and accept the incorporate unit MD1 of the 1st photo detector PD1, the laser module LM etc. of BD information recording surface RL1 folded light beam.

The 2nd semiconductor laser EP1 (the 2nd light source) of luminous ejaculation wavelength X 2=658nm laser beam (the 2nd light beam) when laser module LM has DVD carried out the information recording/reproducing, the 3rd semiconductor laser EP2 (the 3rd light source) of luminous ejaculation wavelength X 3=785nm laser beam (the 3rd light beam) when CD is carried out the information recording/reproducing, accept the 2nd photo detector DS1 of DVD information recording surface RL2 folded light beam, accept the 3rd photo detector DS2 of CD information recording surface RL3 folded light beam, prism PS.

As Fig. 1 (a) and (b), the object lens OBJ of present embodiment, on its light source side aspherics face, be the middle section CN that contains optical axis that formed of centres circle shape ground with the optical axis, be configured in neighboring area MD around it, further be configured in its neighboring area OT on every side.Do not show among the figure, the 1st optical path difference that has formed overlapping the 1st base configuration and the 2nd base configuration on the middle section CN is paid structure, has formed the 2nd optical path difference on the MD of neighboring area and has paid structure.Have on the neighboring area OT and to have formed that the 3rd optical path difference is paid structure and do not form the plane of refraction that the 3rd optical path difference is paid structure.The 1st optical path difference pay structure can adopt 0 time diffraction light quantity for example making the 1st light beam that passes greater than 2 times diffraction light quantity of the diffraction light quantity of other any number of times, the 2nd light beam greater than 3 times diffraction light quantity of the diffraction light quantity of other any number of times, the 3rd light beam greater than the structure of the diffraction light quantity of other any number of times etc., but so long as this instructions first optical path difference is paid can adopting of record in the structure example 1～21.And the 2nd optical path difference is paid structure and the 3rd optical path difference and is paid structure and can pay the selection arbitrarily of structure fit ground with first optical path difference.For example, first optical path difference is paid structure when being above-mentioned example 1, and it is the structure of overlapping the 4th base configuration and the 5th base configuration that preferred the 2nd optical path difference is paid structure.Preferably making the 4th base configuration is that 1 diffraction light quantity is maximum structure when making the 1st light beam and the 2nd light beam; Making the 5th base configuration is that the 1st light beam is the structure that 0 diffraction light quantity maximum, the 2nd light beam are-1 diffraction light quantity maximums.In addition, have the 3rd optical path difference and pay when constructing, preferred the 3rd optical path difference is paid structure and is only formed by the 7th base configuration.The 7th base configuration is a flame-shaped structure, make 2 diffraction light quantities of the 1st light beam that passes greater than 1 diffraction light quantity of the diffraction light quantity of other any number of times, the 2nd light beam greater than 1 diffraction light quantity of the diffraction light quantity of other any number of times, the 3rd light beam diffraction light quantity greater than other any number of times.The area ratio of Fig. 1 (a) and (b) middle section, neighboring area, neighboring area is not correct expression.

The divergent beams of the 1st light beam (λ 1=405nm) that penetrates from bluish violet semiconductor laser LD1, see through dichroism prism PPS, after becoming parallel beam by collimation lens CL, by there not being illustrated quarter wave plate to be transformed into circularly polarized light from rectilinearly polarized light, its beam diameter is incided on the object lens OBJ by diaphragm ST regulation.By the light beam of the middle section of object lens OBJ, neighboring area, neighboring area optically focused, the protective substrate PL1 through thickness 0.1mm forms spot on the information recording surface RL1 of BD.

The folded light beam of on information recording surface RL1, modulating through information track, see through object lens OBJ, diaphragm ST once more, then by there not being illustrated quarter wave plate to be transformed into rectilinearly polarized light from circularly polarized light, CL becomes converging beam by collimation lens, after seeing through dichroism prism PPS, converge on the 1st and be subjected on the sensitive surface of light sub-prime PD1.With the 1st output signal that is subjected to light sub-prime PD1, make object lens OBJ focus on, follow the tracks of by 2 shaft drive AC, can read the information that BD goes up record thus.

The divergent beams of the 2nd light beam (λ 2=658nm) that penetrates from red semiconductor laser EP1, by after the prism PS reflection, through dichroism prism PPS reflection, become parallel beam by collimation lens CL after, through there not being the conversion of illustrated quarter wave plate polarized light, incide on the object lens OBJ.(light beam that passes neighboring area is by hot spotization by the middle section of object lens OBJ and neighboring area optically focused; formation spot periphery) light beam; protective substrate PL2 through thickness 0.6mm forms spot on the information recording surface RL2 of DVD, form the spot central part.

The folded light beam of on information recording surface RL2, modulating through information track, see through object lens OBJ, diaphragm ST once more, then through there not being the conversion of illustrated quarter wave plate polarized light, CL becomes converging beam by collimation lens, after dichroism prism PPS reflection, in prism, be reflected 2 times, converge on the 2nd then and be subjected to light sub-prime DS1.With the 2nd output signal that is subjected to light sub-prime DS1, can read the information that DVD goes up record.By carrying out the polarized light conversion at reciprocal Lu Shangyong λ quarter wave plate, compare with the situation that does not have the λ quarter wave plate, can improve the light utilization ratio.

The divergent beams of the 3rd light beam (λ 3=785nm) that penetrates from infrared semiconductor laser EP2, by after the prism PS reflection, by dichroism prism PPS reflection, become parallel beam by collimation lens CL after, through there not being the conversion of illustrated quarter wave plate polarized light, incide on the object lens OBJ.By the light beam of the middle section optically focused of object lens OBJ (light beam that passes neighboring area and neighboring area is formed the spot periphery by hot spotization), the protective substrate PL3 through thickness 1.2mm forms spot on the information recording surface RL3 of CD.

The folded light beam of on information recording surface RL3, modulating through information track, see through object lens OBJ, diaphragm ST once more, then through there not being the conversion of illustrated quarter wave plate polarized light, CL becomes converging beam by collimation lens, after dichroism prism PPS reflection, in prism, be reflected 2 times, converge on the 3rd then and be subjected to light sub-prime DS2.With the 3rd output signal that is subjected to light sub-prime DS2, can read the information that CD goes up record.By carrying out the polarized light conversion at reciprocal Lu Shangyong λ quarter wave plate, compare with the situation that does not have the λ quarter wave plate, can improve the light utilization ratio.

Claims (23)

1. object lens are used for optical take-up apparatus, and in the described optical take-up apparatus, the 1st light beam of the wavelength X 1 (μ m) that penetrates with the 1st light source carries out the optically focused spot to the information recording surface of the 1st CD of protective seam with thickness t 1 and forms; (information recording surface of the 2nd CD of the protective seam of t1≤t2) carries out the optically focused spot and forms the 2nd light beam of the wavelength X 2 (λ 1＜λ 2) that penetrates with the 2nd light source to having thickness t 2; (information recording surface of the 3rd CD of the protective seam of t2＜t3) carries out the optically focused spot and forms the 3rd light beam of the wavelength X 3 (λ 2＜λ 3) that penetrates with the 3rd light source to having thickness t 3; Object lens are characterised in that,

On the optical surface of described object lens, form first optical path difference and paid structure,

Described first optical path difference is paid the 1st base configuration that structure is a flame-shaped structure and overlapping the forming of the 2nd base configuration of ladder configuration, when overlapping, makes the position consistency of the step of the position of all steps of described the 1st base configuration and described the 2nd base configuration,

Make L, M, when N is arbitrary integer, described the 1st light beam incides described first optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that L diffraction light has maximum, described the 2nd light beam incides described first optical path difference pays that M diffraction light has maximum diffraction light quantity in the diffraction light that takes place when textural, and described the 3rd light beam incides described first optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that N diffraction light has maximum.

As in the claim 1 record object lens, it is characterized in that, described the 2nd base configuration is 4 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(1.2λ1-0.4λ1)/(n-1)≤d1≤(1.2λ1+0.4λ1)/(n-1)

(1.25λ1-0.2λ1)/(n-1)≤d21≤(1.25λ1+0.2λ1)/(n-1)

(3.75λ1-0.2λ1)/(n-1)≤d22≤(3.75λ1+0.2λ1)/(n-1)，

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

3. as the object lens of record in claim 1 or 2, it is characterized in that it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.95λ1-0.2λ1)/(n-1)≤d0≤(4.95λ1+0.2λ1)/(n-1)。

4. the object lens as putting down in writing in any one of claim 1 to 3 is characterized in that, satisfy:

|L|＝2、M＝0、|N|＝1，

The sign symbol of L and N is different.

As in the claim 1 record object lens, it is characterized in that, described the 2nd base configuration is 6 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.2λ1-0.2λ1)/(n-1)≤d21≤(1.2λ1+0.2λ1)/(n-1)

(6λ1-0.2λ1)/(n-1)≤d22≤(6λ1+0.2λ1)/(n-1)，

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

6. as the object lens of record in claim 1 or 5, it is characterized in that it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(5λ1-0.2λ1)/(n-1)≤d0≤(5λ1+0.2λ1)/(n-1)。

7. as the object lens of record in the claim 1,5 or 6, it is characterized in that, satisfy:

L＝0、|M|＝2、|N|＝3，

The sign symbol of M, N is identical.

As in the claim 1 record object lens, it is characterized in that, described the 2nd base configuration is 7 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.31λ1-0.2λ1)/(n-1)≤d21≤(1.31λ1+0.2λ1)/(n-1)

(7.86λ1-0.2λ1)/(n-1)≤d22≤(7.86λ1+0.2λ1)/(n-1)，

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

9. as the object lens of record in claim 1 or 5, it is characterized in that it is the 7 flame ladder configuration of cutting apart that described first optical path difference is paid structure, described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.86λ1-0.2λ1)/(n-1)≤d0≤(4.86λ1+0.2λ1)/(n-1)。

10. as the object lens of record in the claim 1,8 or 9, it is characterized in that, satisfy:

|L|＝1、|M|＝3、|N|＝4，

The sign symbol of L, M, N is identical.

11. the object lens as putting down in writing in any one of claim 1 to 10 is characterized in that,

The optical surface of described object lens has the ring-band shape middle section, the ring-band shape neighboring area that is formed on described its central area that contain optical axis at least, be formed on the neighboring area of ring-band shape around the described neighboring area,

Described the 1st light beam that passes described middle section and described neighboring area and described neighboring area is concentrated on the information recording surface of described the 1st CD,

Described the 2nd light beam that passes described middle section and described neighboring area is concentrated on the information recording surface of described the 2nd CD,

Described the 3rd light beam that passes described middle section is concentrated on the information recording surface of described the 3rd CD,

Described first optical path difference is paid structure and is arranged on the described middle section.

12. an optical take-up apparatus wherein has object lens, the 1st light beam of the wavelength X 1 (μ m) that these object lens penetrate with the 1st light source carries out the optically focused spot to the information recording surface of the 1st CD of protective seam with thickness t 1 and forms; The 2nd light beam of the wavelength X 2 (λ 1＜λ 2) that penetrates with the 2nd light source carries out the optically focused spot to the information recording surface of the 2nd CD of protective seam with thickness t 2 (t1≤t 2) and forms; The 3rd light beam of the wavelength X 3 (λ 2＜λ 3) that penetrates with the 3rd light source to have thickness t 3 (information recording surface of the 3rd CD of the protective seam of t2＜t3) carries out the optically focused spot and forms, and optical take-up apparatus is characterised in that,

On the optical surface of described object lens, form first optical path difference and paid structure,

Described first optical path difference is paid the 1st base configuration that structure is a flame-shaped structure and overlapping the forming of the 2nd base configuration of ladder configuration, when overlapping, makes the position consistency of the step of the position of all steps of described the 1st base configuration and described the 2nd base configuration,

Make L, M, when N is arbitrary integer, described the 1st light beam incides described first optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that L diffraction light has maximum, described the 2nd light beam incides described first optical path difference pays that M diffraction light has maximum diffraction light quantity in the diffraction light that takes place when textural, and described the 3rd light beam incides described first optical path difference pays in the diffraction light that takes place when textural the diffraction light quantity that N diffraction light has maximum.

13. optical take-up apparatus as record in the claim 12, it is characterized in that, described the 2nd base configuration is 4 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(1.2λ1-0.4λ1)/(n-1)≤d1≤(1.2λ1+0.4λ1)/(n-1)

(1.25λ1-0.4λ1)/(n-1)≤d21≤(1.25λ1+0.4λ1)/(n-1)

(3.75λ1-0.4λ1)/(n-1)≤d22≤(3.75λ1+0.4λ1)/(n-1)，

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

14. optical take-up apparatus as record in claim 12 or 13, it is characterized in that, it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.95λ1-0.4λ1)/(n-1)≤d0≤(4.95λ1+0.4λ1)/(n-1)。

15. the optical take-up apparatus as putting down in writing in any one of claim 12 to 14 is characterized in that, satisfies:

|L|＝2、M＝0、|N|＝1，

The sign symbol of L, N is different.

16. optical take-up apparatus as record in the claim 12, it is characterized in that, described the 2nd base configuration is 6 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(λ1-0.4λ1)/(n-1)≤d1≤(λ1+0.4λ1)/(n-1)

(1.2λ1-0.4λ1)/(n-1)≤d21≤(1.2λ1+0.4λ1)/(n-1)

(6λ1-0.4λ1)/(n-1)≤d22≤(6λ1+0.4λ1)/(n-1)，

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

17. optical take-up apparatus as record in claim 12 or 16, it is characterized in that, it is the 4 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(5λ1-0.4λ1)/(n-1)≤d0≤(5λ1+0.4λ1)/(n-1)。

18. the optical take-up apparatus as record in the claim 12,16 or 17 is characterized in that, satisfies:

L＝0、|M|＝2、|N|＝3，

The sign symbol of M, N is identical.

19. optical take-up apparatus as record in the claim 12, it is characterized in that, described the 2nd base configuration is 7 ladder configuration of cutting apart, the optical axis direction of the described step of the length d 22 (μ m) of the optical axis direction of the big step of the ladder configuration of the length d 21 of the optical axis direction of the small stair of the ladder configuration of described the 2nd base configuration (μ m), described the 2nd base configuration, described the 1st base configuration length d 1 (μ m) formula meets the following conditions:

(3λ1-0.4λ1)/(n-1)≤d1≤(3λ1+0.4λ1)/(n-1)

(1.31λ1-0.4λ1)/(n-1)≤d21≤(1.31λ1+0.4λ1)/(n-1)

(7.86λ1-0.4λ1)/(n-1)≤d22≤(7.86λ1+0.4λ1)/(n-1)，

The refractive index of the described object lens when wherein, n represents described the 1st light beam.

20. optical take-up apparatus as record in claim 12 or 19, it is characterized in that, it is the 7 flame ladder configuration of cutting apart that described first optical path difference is paid structure, and described first optical path difference is paid the length d 0 (μ m) of optical axis direction of the maximum step of structure, and formula meets the following conditions:

(4.86λ1-0.4λ1)/(n-1)≤d0≤(4.86λ1+0.4λ1)/(n-1)。

21. the optical take-up apparatus as record in the claim 12,19 or 20 is characterized in that, satisfies:

|L|＝1、|M|＝3、|N|＝4，

The sign symbol of L, M, N is identical.

22. the optical take-up apparatus as putting down in writing in any one of claim 12 to 21 is characterized in that,

The optical surface of described object lens has the ring-band shape middle section, the ring-band shape neighboring area that is formed on described its central area that contain optical axis at least, be formed on the neighboring area of ring-band shape around the described neighboring area,

Described the 1st light beam that passes described middle section and described neighboring area and described neighboring area is concentrated on the information recording surface of described the 1st CD,

Described the 2nd light beam that passes described middle section and described neighboring area is concentrated on the information recording surface of described the 2nd CD,

Described the 3rd light beam that passes described middle section is concentrated on the information recording surface of described the 3rd CD,

Described first optical path difference is paid structure and is arranged on the described middle section.

23. the optical take-up apparatus as putting down in writing in any one of claim 12 to 22 is characterized in that,

The imaging multiplying power m3 of the imaging multiplying power m1 of the described object lens when described the 1st light beam incides on the described object lens, the imaging multiplying power m2 of the described object lens when described the 2nd light beam incides on the described object lens, the described object lens when described the 3rd light beam incides on the described object lens, satisfy following formula (1), (2), (3) respectively:

-0.02＜m1＜0.02 (1)

-0.02＜m2＜0.02 (2)

-0.02＜m3＜0.02 (3)。

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