JP2006284635A - Optical block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical block with which a plurality of optical elements nearly in the same shape can easily be discriminated without deteriorating optical characteristics. <P>SOLUTION: The optical block 11 is constituted by joining together the plurality of optical elements 12 and 13 nearly in the same shape, and the optical elements 12 and 13 have antireflective films 122a and 132a reducing reflection factors of their surfaces, the antireflective films 122a and 132a of the optical elements 12 and 13 being made different in color. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical block formed by joining a plurality of optical elements having substantially the same shape. More specifically, the present invention relates to an antireflection film formed on the surface of an optical element.

  As an optical block formed by joining a plurality of optical elements having substantially the same shape, for example, a cube prism in which two triangular prisms having substantially the same shape are joined via a partial reflection surface inclined obliquely with respect to the optical axis. is there.

  For example, in an optical head device 10 used for recording and reproduction of an optical recording disk such as a CD or a DVD as shown in FIG. 1, the cube prism 11 uses laser light emitted from a laser light emitting element 15 as a collimating lens 17. In the meantime, the return light from the optical recording medium 23 is reflected toward the light receiving element 21.

For example, as shown in FIG. 6, a conventional cube prism 110 has a first prism structure 12 and a second prism structure 131 that are made of the same material and have a right triangle in cross section. The second prism constituent bodies 12 and 131 are joined via a partial reflection surface 14 inclined obliquely with respect to the optical axis L of the laser light emitted from the laser light emitting element 15.
An optical multilayer film 121 having a light transmission characteristic or a light reflection characteristic is formed on the slope of the first prism constituting body 12 constituting the partial reflection surface 14, and this optical multilayer film 121 serves as a light separation function or light. Works as a composite function.
Further, an antireflection film 122 for reducing the reflectance of the surface of the first prism constituting body 12 other than the slope is formed.
Similarly, antireflection films 132 and 133 for reducing the reflectance are formed on the surface of the second prism component 131 other than the inclined surface.

In order to obtain a predetermined light transmission characteristic or light reflection characteristic when the cube prism 110 is arranged in the optical head device 10, either the first prism component 12 or the second prism component 131 is provided with an optical multilayer film. It is necessary to identify whether 121 is formed.
Therefore, in order to identify the first prism structure 12 on which the optical multilayer film 121 is formed, for example, either the first prism structure 12 or the second prism structure 131 is shown in FIG. The chamfered portion 134 was formed on the second prism structure 131 before or after film formation.
Further, when the chamfered portion 134 is formed after the film formation, it is necessary to identify the chamfered portion 134 until the chamfered portion 134 is formed.
Further, when the chamfered portion 134 is formed, the number of processing steps is increased, so that one surface of the first prism structure 12 or the second prism structure 131 is not polished but is made rough as it is.

However, when the chamfered portion 134 is formed or when marking is performed with a diamond pen or the like, the substrate of the optical element such as the prism structure is processed, so that there is a risk that strain stress or the like may remain.
Further, when marking with an oil-based pen or the like, there is a problem that the optical element becomes dirty. That is, they may deteriorate the optical characteristics of an optical block such as a cube prism.

  In addition, when a certain surface other than chamfering is left as a rough surface without being polished, the surface on which the rough surface is formed cannot be used as an optical function, and the use (function) of the optical element is limited. There was a problem.

  In view of the above problems, an object of the present invention is to provide an optical block that can easily identify a plurality of optical elements having substantially the same shape without degrading optical characteristics.

  In order to solve the above problems, the present invention is an optical block formed by joining a plurality of optical elements having substantially the same shape, and each optical element is formed with an antireflection film for reducing the reflectance of the surface thereof. And the color of the antireflection film of each optical element is different.

  In the present invention, an optical block is formed by joining a plurality of optical elements having substantially the same shape. Each optical element is provided with an antireflection film for reducing the reflectance of the surface, and the reflection of each optical element. Since the color of the prevention film is different, the plurality of optical elements can be identified by visual observation. Therefore, it can be easily recognized visually without degrading the optical characteristics of the optical block.

  Furthermore, since the surface with the optical element is not polished as it is without being roughened, the entire surface of the optical element can be used, so that the application (function) of the optical block is not narrowed.

  In the present invention, the optical block is a cube-type prism, and the first prism structure and the second prism structure having substantially the same triangular prism shape are joined via a partial reflection surface inclined obliquely with respect to the optical axis. In addition, it is preferable that an optical multilayer film having light transmission characteristics and light reflection characteristics is formed on one of the partial reflection surfaces of the first prism structure or the second prism structure.

  According to the present invention, the first prism structure and the second prism structure having the same shape can be easily identified by visually observing the color of the antireflection film without degrading the optical characteristics of the cube prism. be able to. In addition, the entire surface of the cube prism can be used effectively, and can be applied to an optical head device provided with laser light emitting elements having different wavelengths.

  Furthermore, in the present invention, the wavelength range of the antireflection film of each optical element is preferably other than the wavelength range of the laser light incident on the optical block in the previous period. For this reason, since the laser beam incident on the optical block is not affected, the optical characteristics of the optical block are not deteriorated.

  In the present invention, an optical block is formed by joining a plurality of optical elements having substantially the same shape. Each optical element is provided with an antireflection film for reducing the reflectance of the surface, and the reflection of each optical element. Each of the prevention films is different in color.

  In the present invention, an optical block is formed by joining a plurality of optical elements having substantially the same shape. Each optical element is provided with an antireflection film for reducing the reflectance of the surface, and the reflection of each optical element. Since the prevention films have different colors, they can be identified by visually observing the plurality of optical elements. Therefore, it can be easily recognized visually without degrading the optical characteristics of the optical block.

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

  FIG. 1 is a schematic configuration diagram mainly showing an optical system of an optical head device having a cube-type block having a preferred embodiment of the optical block of the present invention.

An optical head device 10 shown in FIG. 1 performs information recording and information reproduction on an optical recording medium 23 such as a DVD, and a laser light emitting element 15 composed of a laser diode that emits a laser beam having a wavelength of 650 nm. A grating 16 that splits the laser light emitted from the element 15 into three beams, a cube prism 11 that the laser light emitted from the laser light emitting element 15 enters through the grating 16, and a laser beam that has passed through the cube prism 11 Are arranged in this order on the optical path. The collimator lens 17 for collimating the light beam, the rising mirror 18, and the objective lens 19 for condensing the parallel light beam emitted from the collimator lens 17 on the optical recording medium 23 are arranged.
The cube prism 11 is an optical block formed by joining a plurality of optical elements having substantially the same shape, and is an optical path separating element or an optical path combining element.
In the optical system shown in FIG. 1, the cube prism 11 is used as an optical path separation element.

A light receiving element 21 and a sensor lens 20 are disposed on the side of the cube prism 11, and return light reflected by the optical recording medium 23 passes through the objective lens 19, the rising mirror 18, and the collimator lens 17. Then, the light enters the cube prism 11, and the optical axis L thereof is bent at a right angle by the partial reflection surface 14 and guided toward the sensor lens 20 and the light receiving element 21.
Further, a lens driving device 22 is configured to drive the objective lens 19 in the focusing direction and the tracking direction.

(Configuration of cube prism)
FIG. 2 is a schematic diagram showing a cube prism 11 having a preferred embodiment of the optical block of the present invention.

The cube prism 11 as an optical block formed by joining a plurality of optical elements having substantially the same shape partially reflects the first prism structure 12 having a triangular prism shape and the second prism structure 13 having a similar triangular prism shape. In the optical head device 10 shown in FIG. 1, the partial reflection surface 14 is 45 degrees with respect to the optical axis L of the laser light emitted from the laser light emitting element 15. Tilt at an angle of.
The cube prism 11 is a plurality of optical elements having substantially the same shape, and each optical element includes a first prism structure 12 and a second prism structure 13.

The first prism structure 12 is formed of a transparent base whose cross-sectional shape is a right triangle. In the present embodiment, the first prism structure 12 is a glass optical member and is transparent at least in the visible light region.
In addition, an optical multilayer film 121 having light transmission characteristics or light reflection characteristics is formed on the inclined surface joined to the second prism structure 13.
Further, an antireflection film 122a for reducing the reflectance of the surface is formed on the surface other than the inclined surface to be joined, that is, the surface on which the laser light emitted from the laser light emitting element 15 is incident in FIG. .

The optical multilayer film 121 realizes a predetermined light transmission / reflection characteristic by alternately laminating a low refractive index material and a high refractive index material and utilizing the light interference effect. Examples of the low-refractive index material include SiO2 and MgF2, and examples of the high-refractive index material include TiO2, NbO2, and Ta2O5. And by controlling the thickness of each layer and the like, the light polarization component is separated with a predetermined efficiency.
Note that the optical multilayer film 121 is a known one, and a detailed description thereof is omitted here.

  The second prism structure 13 is made of a transparent substrate having substantially the same shape and the same quality as the first prism structure 12, and a cross-sectional shape of a right triangle. In the present embodiment, the second prism structure 13 is a glass optical member. , At least in the visible light region.

Further, antireflection films 132 a and 133 a for reducing the reflectance are formed on the second prism structure 13 on the surface other than the inclined surface joined to the first prism structure 12.
Specifically, the return light reflected by the optical recording medium 23 is incident on the second prism component 12 of the cube prism 11 via the collimator lens 17, and faces the sensor lens 20 and the light receiving element 21. Formed on the surface.

(About antireflection film)
In the present embodiment, the antireflection film 122a formed on the first prism structure 12 and the antireflection film 132a (133a) formed on the second prism structure 13 can be visually recognized. In addition, each antireflection film is colored.
Although the antireflection films 132a and 133a are formed on the two surfaces of the second prism structure 13, it is sufficient that the second prism structure 13 can be visually recognized as the first prism structure 12, so these two antireflection films The antireflection film 132a and / or 133a may be colored.

In general, when white light strikes an object, some colors (wavelengths) are absorbed and the remaining colors (wavelengths) are scattered and reach the observer's eyes. This scattered light is recognized as the color of the object.
That is, by setting the color (wavelength range) to be reflected in the antireflection films 122a and 132a (133a), the colors of the antireflection films 122a and 132a (133a) are colored.

In order to be able to visually recognize the colors of the antireflection films 122a and 132a (133a), it is necessary to set the wavelength range within the visible light band (380 to 770 nm).
In this embodiment, since the optical head device 10 shown in FIG. 1 is used for a DVD, the laser light emitting element 15 emits laser light having a wavelength of 640 to 660 nm.
Therefore, the antireflection films 122a and 132a (133a) use a wavelength range excluding the wavelength range of 640 to 660 nm in the visible wavelength range of 380 to 770 nm.
From the above, the usable wavelength range is 380 to 640 nm or 660 to 770 nm.

Furthermore, in view of spectral characteristics, it is difficult to have a steep waveform, that is, unless the transmittance is kept high to some extent in the vicinity of the wavelength range (640 to 660 nm) used for DVD, The apparatus 10 is affected, and there is a possibility that data on the information medium cannot be read accurately.
Therefore, in order to use a wavelength range that does not affect the laser beam of the optical head device 10, the wavelength range of about 30 nm away from the wavelength range (640 to 660 nm) of the laser beam used in the DVD is designed. Yes.

More specifically, a wavelength range of 380 nm and 770 nm from both ends of visible light is used, and a wavelength range of 400 to 600 nm, or a wavelength range of 700 to 750 nm can be used for identification. It is considered a wavelength range.
Among these, since the wavelength range of 700 to 750 nm is narrow, the accuracy of film formation must be increased. Therefore, in this embodiment, the band for reducing the transmittance of the antireflection films 122a and 132a (133a) is wide. It is designed using a wavelength range of 400 to 600 nm.

  Hereinafter, the structure of the antireflection film 122a of the first prism structure 12 and the structure of the antireflection film 132a (133a) of the second prism structure 13 will be described separately for each embodiment.

(Embodiment 1 of antireflection film)
Table 1 shows the film structure of the antireflection film formed on the first prism structure. Table 2 shows the film structure of the antireflection film formed on the second prism structure. FIG. 3 is a graph showing light transmittance in each antireflection film of the first or second prism structure according to the first embodiment.

第１のプリズム構成体１２に形成される反射防止膜１２２ａは、４００〜６００ｎｍに透過率を低くするように設計されており、具体的には、表１に示すように、透明基体としてのガラス光学部材（ＢＫ７：ショット社の名称）に、基体側の第１層と第１１層（最終層）をＳｉＯ２とし、その間にＳｉＯ２とＮｂ２Ｏ５とを互いに蒸着またはスパッタリングを用いて積層して形成されている。各層の膜厚は表１に示すとおりとなっている。
これにより、図３に示すように、本実施の形態では反射防止膜１２２ａは、波長４３０ｎｍ付近をピークとし、その波長での透過率を約４０％とした膜が形成されており、目視すると濃い青色として認識することができるようになっている。

The antireflection film 122a formed on the first prism structure 12 is designed to reduce the transmittance to 400 to 600 nm. Specifically, as shown in Table 1, glass as a transparent substrate is used. The optical member (BK7: name of Schott) is formed by laminating the first layer and the eleventh layer (final layer) on the substrate side with SiO2, and laminating SiO2 and Nb2O5 by vapor deposition or sputtering. Yes. The film thickness of each layer is as shown in Table 1.
As a result, as shown in FIG. 3, in the present embodiment, the antireflection film 122a is formed with a film having a peak near the wavelength of 430 nm and a transmittance of about 40% at that wavelength, which is dark when visually observed. It can be recognized as blue.

On the other hand, the antireflection film 132a (133a) of the second prism structure 13 is similarly designed to have a low transmittance of 400 to 600 nm. It is formed by laminating SiO2 and Nb2O5 on each other by vapor deposition or sputtering on a glass optical member (BK7: name of Schott) on the first layer and the seventh layer (final layer) on the substrate side. ing. The film thickness of each layer is as shown in Table 2.
As a result, as shown in FIG. 3, in the present embodiment, the antireflection film 132a (133a) is formed with a film having a peak at a wavelength of about 410 nm and a transmittance at that wavelength of about 75%. When visually observed, it can be recognized as colorless to light blue.

Thus, the antireflection film 122a of the first prism structure 12 can be visually recognized as dark blue, and the antireflection film 132a (133a) of the second prism structure 13 can be visually recognized as colorless to light blue. It has become.
For reference, FIG. 7 shows the light transmittance in the conventional antireflection film, and Table 3 shows the film configuration of the conventional antireflection film.

(Embodiment 2 of antireflection film)
In the first embodiment described above, the wavelength range of the transmittance is almost the same. However, although the color is given by changing the transmittance, the wavelength range may be changed.
Table 4 shows the film configuration of another antireflection film formed on the first prism structure. Table 5 shows the film configuration of another antireflection film formed on the second prism structure. FIG. 4 is a graph showing the light transmittance of each antireflection film of the first or second prism structure according to the second embodiment.

The antireflection film 122a formed on the first prism structure 12 is designed to lower the transmittance to 400 to 600 nm. Specifically, as shown in Table 3, glass as a transparent substrate is used. The optical member (BK7: name of Schott) is formed by laminating the first layer and the eleventh layer (final layer) on the substrate side with SiO2, and laminating SiO2 and Nb2O5 by vapor deposition or sputtering. Yes. The film thickness of each layer is as shown in Table 3.
As a result, as shown in FIG. 4, in the present embodiment, the antireflection film 122a is formed with a film having a peak near the wavelength of 450 nm and a transmittance of about 40% at that wavelength. Can be recognized as.

On the other hand, the antireflection film 132a (133a) of the second prism structure 13 is similarly designed to reduce the transmittance to 400 to 600 nm, but as shown in Table 4, as a transparent substrate. A glass optical member (BK7: name of Schott) is formed by laminating the first layer and the eleventh layer (final layer) on the substrate side with SiO2, and laminating SiO2 and Nb2O5 between each other by vapor deposition or sputtering. ing. The film thickness of each layer is as shown in Table 4.
As a result, as shown in FIG. 4, in the present embodiment, the antireflection film 132a (133a) is formed with a film having a peak near the wavelength of 500 nm and a transmittance of about 45% at that wavelength. When it is visually observed, it can be recognized as green.

  Thus, the antireflection film 122a of the first prism structure 12 can be visually recognized as blue, and the antireflection film 132a (133a) of the second prism structure 13 can be recognized as green. .

(Cube type prism manufacturing method)
5A to 5C are explanatory views showing a method for manufacturing a cube-type prism according to the embodiment of the present invention.

  In the present embodiment, as shown in FIG. 5A, a right triangular prism-shaped transparent base (glass optical member: BK7) 1200, 1300 for constituting the first and second prism constituent bodies 12, 13 is provided. Prepare several.

In FIG. 5A, an optical multilayer film 121 is formed on a slope 1200a of a transparent substrate (glass optical member: BK7) 1200 for constituting the first prism structure 12 by a method such as vapor deposition or sputtering. Yes.
The optical multilayer film 121 realizes a predetermined light transmission / reflection characteristic by alternately laminating a low refractive index material and a high refractive index material and utilizing the light interference effect.
Note that the optical multilayer film 121 is a known one, and a detailed description thereof is omitted here.
Further, an antireflection film 122a for reducing the reflectance is formed on the surface 1200b of the transparent substrate 1200 by a method such as vapor deposition or sputtering.
The material and film thickness of the antireflection film 122a are as shown in Table 1 or Table 3.

Similarly, on the surfaces 1300a and 1300b of the transparent substrate (glass optical member: BK7) 1300 for forming the second prism structure 13, antireflection films 132a and 133a for reducing the reflectance are deposited or sputtered. It is formed by the method.
The materials and film thicknesses of the antireflection films 132a and 133a are as shown in Table 2 or Table 4.

Then, as shown in FIG. 5B, the transparent base body 1200 and the transparent base body 1300 are joined to each other as the partial reflection surface 14 to form a cube prism laminate 1100 as an optical block.
When the two transparent substrates 1200 and 1300 are bonded, the two transparent substrates 1200 and
An ultraviolet curable adhesive or the like is interposed between 1300 and cured.

  Next, as shown in FIG. 5C, the laminate 1100 in which the transparent substrates 1200 and 1300 are bonded together is cut at a predetermined interval in the longitudinal direction. As a result, a plurality of cube prisms 11 in which the first prism structure 12 having a triangular prism shape and the second prism structure 13 having a similar triangular prism shape shape are joined via the partial reflection surface 14 are manufactured.

  (Effect of this embodiment)

  The cube prism 11 is composed of two first prism constituent bodies 12 and a second prism constituent body 13 that are substantially triangular, and the first prism constituent body 12 has a reduced surface reflectance. The antireflection film 122a is formed. Similarly, the antireflection films 132a and 133a are formed on the second prism structure 13, and the antireflection film 122a formed on the first prism structure 12 is formed. And the color of the antireflection film 132a or 133a formed on the second prism structure 13 are made different.

  In the cube prism 11, the color of the antireflection film 122a formed on the first prism structure 12 and the color of the antireflection film 132a or 133a formed on the second prism structure 13 are different. The first and second prism structures 12 and 13 can be identified by visual observation. Therefore, it can be easily recognized visually without degrading the optical characteristics of the cube prism 11.

  In addition, since the surfaces having the first and second prism constituent bodies 12 and 13 are not polished and are not roughened as they are, all the surfaces of the first and second prism constituent bodies 12 and 13 are used. Therefore, the application (function) of the cube prism 11 is not narrowed.

  Further, unlike the prior art, the chamfered portion 134 is not formed on the surface of one of the prism structures 12 and 13 before the optical multilayer film 121 is formed. The loss of inventory and the like can be reduced without preparing a prism structure that is not formed and two types of prism structures.

Further, in the cube prism 11, the first prism structure 12 and the second prism structure 13 having substantially the same triangular prism shape are joined via a partial reflection surface 14 inclined obliquely with respect to the optical axis L, and An optical multilayer film 121 having light transmission characteristics and light reflection characteristics is formed on one of the partial reflection surfaces 14 of the first prism structure 12 or the second prism structure 13.
Therefore, the entire surface of the cube prism 11 can be used effectively, and the present invention can be applied to an optical head device including the laser light emitting elements 1 having different wavelengths.

  Further, as described above, the cube prism 11 includes the first prism structure 12 and the second prism structure 13 having substantially the same shape, and antireflection films 122a and 132a (133a) formed on the prism structures. ) Can be easily identified by visual inspection. Therefore, the first prism structure 12 on which the optical multilayer film 121 is formed can be easily distinguished from the second prism structure 13, so that the cube prism 11 can be accurately connected to the optical head device. 10 and a predetermined light transmission characteristic or light reflection characteristic can be obtained.

  Further, since the wavelength ranges of the antireflection films 122a and 132a (133a) formed on the first prism structure 12 and the second prism structure 13 use a band of 400 to 600 nm, the optical head The wavelength is outside the wavelength range (640 to 660 nm) of the laser beam of the laser light emitting element 12 for DVD used in the apparatus 10. For this reason, the laser beam incident on the cube prism 11 is not affected, and the optical characteristics of the optical head device 10 are not deteriorated.

[Other embodiments]
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.
For example, in the present embodiment, the antireflection film has a low transmittance at 400 to 600 nm. However, the present invention is not limited to this, and the transmittance may be lowered by using a wavelength region of 700 to 750 nm.

In the present embodiment, the optical head device 10 is for DVD (640 to 660 nm), but may be for CD (780 to 800 nm).
Furthermore, it may be applied to an optical head device that supports a next-generation optical disk and uses a wavelength region of 400 to 410 nm. In this case, it is necessary to avoid the color region of the antireflection film in the wavelength region of 400 to 410 nm.

  In addition, in order to perform information recording and information reproduction on the DVD and CD as the optical recording medium 23, a first laser emitting element that emits laser light having a wavelength of 650 nm and a first laser light that emits laser light having a wavelength of 780 nm. The present invention may be applied when manufacturing a composite prism used in a two-wavelength optical head device including two light emitting elements.

In the present embodiment, the cube prism 11 in which the first prism structure 12 and the second prism structure 13 each having a right isosceles triangular prism shape are joined via the partial reflection surface 14 is described as an example. In addition to this, the present invention can be applied to an irregular prism in which the partial reflection surface 14 forms an angle other than 45 degrees with respect to the optical axis L of the laser light emitted from the laser light emitting element 15. Good.
Further, in addition to the polarization separation film and the half mirror film as the optical multilayer film 121, a retardation film or the like may be interposed.
Furthermore, the optical multilayer film 121 may be formed not on the first prism structure but on the second prism structure.

It is a schematic block diagram which shows centering on the optical system of the optical head apparatus provided with the cube-type block which has preferable embodiment of the optical block of this invention. It is a schematic block diagram which shows the cube-type prism 11 which has preferable embodiment of the optical block of this invention. 4 is a graph showing light transmittance in each antireflection film of the first or second prism structure according to the first embodiment. 6 is a graph showing light transmittance in each antireflection film of the first or second prism structure according to the second embodiment. (A)-(c) is explanatory drawing which shows the manufacturing method of the cube-type prism which concerns on embodiment of this invention. It is a schematic block diagram which shows the conventional cube type prism. It is a graph which shows the light transmittance in each antireflection film of the conventional 1st or 2nd prism structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical head apparatus 11 Cube-type prism 12 1st prism structure 121 Optical multilayer film 122a Antireflection film 13 2nd prism structure 132a, 133a Antireflection film 14 Partial reflection surface 15 Laser light emitting element

Claims (3)

  An optical block formed by joining a plurality of optical elements having substantially the same shape. Each optical element is provided with an antireflection film for reducing the reflectance of the surface, and the color of the antireflection film of each optical element. An optical block characterized in that the two are different.   The optical block is a cube-type prism, and the first prism structure and the second prism structure having substantially the same triangular prism shape are joined via a partially reflecting surface inclined obliquely with respect to the optical axis. 2. The optical block according to claim 1, wherein an optical multilayer film having a light transmission characteristic and a light reflection characteristic is formed on a partial reflection surface of one of the first prism structure and the second prism structure. 3. The optical block according to claim 1, wherein a wavelength range for making the color of the antireflection film of each optical element different is other than a wavelength range of laser light incident on the optical block in the previous period.

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