JP2000066074A - Optical element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively produce an optical element for diffracting light. SOLUTION: The rugged patterns of plural diffraction gratings 32 constituting a beam splitter 32 are arrayed and formed on a silicon wafer 31 by an electron beam writing system to form a father 33 transferred with the rugged patterns (32) of the wafer 31. A mother 34 transferred with the rugged patterns (32) of this father 33 is formed and a stamper 3 transferred with the rugged patterns (32) of this mother is formed. This stamper 35 and a lens metal mold 36 are then mounted at a molding device and a resin of a lens material is poured into this lens metal mold 36 and is molded, by which the lens 37 transferred with the rugged patterns (32) of the stamper 35 is formed. A thin film is formed by sputtering of a metal or the like on the surface of this lens 37 and a pinhole film 38 is formed, by which the lens 37, the beam splitter 32 and the pinhole film 38 are integrated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical element for diffracting light and a method for manufacturing the same.

[0002]

2. Description of the Related Art Prepaid cards, credit cards,
A magnetic card such as a cash card has a magnetic recording section called a magnetic stripe as recording means. For example, in the case of a prepaid card, the balance associated with use is recorded in the magnetic recording unit, and an ID (identification) number or the like is recorded as necessary to identify the person. Such a magnetic card is convenient to carry and contributes to a so-called cashless society without cumbersome cash transfer.
On the other hand, in such a magnetic card, since the recording medium is a magnetic recording layer, the recorded contents can be easily read, and therefore, it is easy to forge, so that a large number of telephone cards and prepaid cards of pachinko parlors are forged. It is often misused and has become a social problem.

In order to cope with such forgery and unauthorized use, complicated magnetic recording systems and IC cards have been proposed in place of conventional simple magnetic recording systems, but this method is costly. There is a problem and it is not widespread. Therefore, as an alternative method, an optical recording method using a diffraction grating or a hologram is disclosed in, for example,
These are proposed in, for example, JP-A-71383, JP-A-5-73738, and JP-B-7-97388.

In the conventional optical recording method disclosed in the above publication, it is a method of determining whether or not the reflection intensity of light on a hologram is a predetermined value (or not less than a predetermined value),
Since this is a method of detecting a plurality of different optical paths of reflected light using a diffraction grating or a hologram, it is useful to identify whether a card is authentic (authentic) or counterfeit. However,
For example, it is not suitable for recording the amount of a prepaid card, a PIN or a card number in a cash card,
If this information is to be recorded using the conventional optical recording method disclosed in the above publication, a huge number of holograms must be arranged. Further, in order to accurately reproduce recorded information as well as to manufacture a card, a reading device (reader) becomes extremely complicated and requires a very large cost, which is considered to be difficult to realize.

[0005]

By the way, the applicant of the present invention disclosed in the earlier application (Japanese Patent Application No. 8-346617, etc.) complicated information such as the amount of a prepaid card, a personal identification number and a card number in a cash card. Proposed a low-cost optical card suitable for recording the optical card, and a recording / reproducing apparatus for the optical card.

However, the monochromatic light generator used in this recording / reproducing apparatus uses monochromatic diffused light such as a semiconductor laser (LD) 1 or LED as a light source as shown in FIG. Since the converged monochromatic light is condensed by the convex lens 2, the irradiation range of the condensed monochromatic light is limited by the pinhole 3, and the monochromatic light is then split into a plurality of (eg, seven) beams by the beam splitter 4. As shown in Japanese Patent Publication No. 7-97388 (FIG. 3), as compared with the configuration of only a semiconductor laser and a lens, each optical element requires extremely high precision, and assembly adjustment is performed so that the beam does not tilt. Since precision is also required, there is a problem that a great cost is required.

A Fresnel lens is known as another optical element for diffracting light. A plurality of annular convex lens patterns are formed on the Fresnel lens, and one annular pattern is formed stepwise. As a conventional method of manufacturing this Fresnel lens, an oxide film (SiO 2) is formed on a Si substrate in a first step as shown in FIG.
₂ ) is formed, a photoresist is applied on the oxide film, and the photoresist is exposed and etched through a mask of the first pattern to form a one-step annular convex lens pattern on the oxide film. Form. Then, this process is performed in the second, third,.
By repeating using the mask of the pattern
Are sequentially formed to form a plurality of annular convex lens patterns. Therefore, in this conventional manufacturing method, the above-described steps are repeated by the number of patterns (ie, steps), and the number of masks is required by the number of patterns.

An object of the present invention is to provide an optical element which can be manufactured at low cost and a method for manufacturing the same, in view of the problems of the above-mentioned conventional examples.

[0009]

According to a first aspect of the present invention, a beam splitter and a pinhole are integrated using an electron beam drawing apparatus in order to achieve the above object.

According to the first aspect of the present invention, in an optical element for converging monochromatic diffused light by a convex lens, restricting an irradiation range by a pinhole, and diffracting a plurality of beams by a beam splitter, Forming the beam splitter by forming a diffraction grating pattern and duplicating the diffraction grating pattern, forming the pinhole by applying a pinhole film on the surface of the beam splitter, forming the pinhole, An optical element characterized by integrating a pinhole is provided.

According to the first aspect of the present invention, there is provided a method of manufacturing an optical element, wherein monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and diffracted into a plurality of beams by a beam splitter. Forming a diffraction grating pattern by an electron beam drawing apparatus; forming the beam splitter by duplicating the diffraction grating pattern; and coating the pinhole by coating a pinhole film on the surface of the beam splitter. Forming the beam splitter and the pinhole into a single unit.

According to a second aspect of the present invention, in order to achieve the above object, a pinhole is formed by applying a pinhole film to the surface of a convex lens, and the convex lens and the pinhole are integrated.

According to the second aspect of the present invention, in the optical element, the monochromatic diffused light is condensed by the convex lens, the irradiation range is limited by the pinhole, and the beam is split into a plurality of beams by the beam splitter. An optical element is provided in which the pinhole is formed by applying a pinhole film to a surface, and the convex lens and the pinhole are integrated.

According to a second aspect of the present invention, there is provided a method for manufacturing an optical element, wherein monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and diffracted into a plurality of beams by a beam splitter. A method of manufacturing an optical element, comprising: forming a pinhole by applying a pinhole film to a surface of the convex lens to integrate the convex lens and the pinhole.

According to a third aspect of the present invention, in order to achieve the above object, a beam splitter and a convex lens are integrated using an electron beam drawing apparatus. Further, the beam splitter, the convex lens and the pinhole are integrated.

According to the third aspect of the present invention, there is provided an optical element in which monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and is diffracted into a plurality of beams by a beam splitter. Forming a diffraction grating pattern of the beam splitter by an apparatus, forming a stamper of the beam splitter by duplicating the diffraction grating pattern, and integrally forming the beam splitter and the convex lens by the stamper and a lens mold. An optical element is provided.

According to a third aspect of the present invention, there is provided a method for manufacturing an optical element, comprising: condensing monochromatic diffused light by a convex lens, restricting an irradiation range by a pinhole, and diffracting a plurality of beams by a beam splitter. Forming a diffraction grating pattern of the beam splitter with an electron beam writing apparatus; forming a stamper of the beam splitter by duplicating the diffraction grating pattern; and forming the beam splitter and the convex lens by the stamper and a lens mold. And a step of integrally forming the optical element.

According to a fourth aspect of the present invention, in order to achieve the above object, an optical element having a diffraction grating formed on the surface of a convex lens is formed by an electron beam drawing apparatus.

That is, according to the fourth aspect, in the method of manufacturing an optical element in which a diffraction grating is formed on the surface of a convex lens, a diffraction grating pattern is formed by an electron beam drawing apparatus, and the diffraction grating pattern is duplicated. A method of manufacturing an optical element, comprising: forming a stamper of the diffraction grating; and forming the diffraction grating on a surface of the convex lens using the stamper and a lens mold.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an optical card to which a first embodiment of an optical element according to the present invention is applied, and FIG.
1 is a configuration diagram showing a monochromatic light generating device that generates monochromatic diffracted light with respect to the optical card of FIG. 1, FIG. 3 is a configuration diagram showing an optical element according to the present invention, and FIG. FIG. 5 is a side view showing the optical element shown in FIGS. 3 and 4.

FIG. 1B is a side sectional view of an optical recording medium (optical card) 10 to which the optical element according to the present invention is applied.
The optical card 10 has a substrate 11, a recording layer, a reflective film 13 made of, for example, aluminum, and a UV protective film 14 laminated on each other.
It has a rectangular shape of 5 mm × 75 mm. Substrate 11
For example, polycarbonate or the like can be used, and as the UV protective film 14, for example, a UV polymer coat can be used. A plurality of hologram interference fringes generated by calculation based on two-dimensional image data are formed on the recording layer, and these hologram interference fringes are called CGH (computer generated hologram) 12.

FIG. 1A is a top view as seen from the substrate 11 side. CGH 12 is shown by a square, and reflection film 13 is formed by a CG.
It is shown as an area larger than H12. Multiple CGHs
12 are arranged in the vertical and horizontal directions, one of which is, for example, 100 μm, and the interval is 250 μm. Part 1
Each one represents a character. For example, when used as a prepaid card, it represents a certain amount of money.

When reproducing such a CGH 12, a monochromatic light generator 20 as shown in FIG. 2 is used. In the example shown in FIG. 2, since six CGHs 12 are arranged in the horizontal direction, the monochromatic light generating device 20 has a total of seven non-diffracted central rays and six diffracted outer rays.
A beam is generated, and six CGHs 12 in the horizontal direction are irradiated at a time by the six diffracted beams. Further, by moving the monochromatic light generating device 20 or the CGH 12 in the vertical direction, the two-dimensionally arranged CGHs 12 are irradiated to read the reflected light. Although the beam spot BS is shown as an ellipse, it may be circular.

FIG. 3 shows a monochromatic light generator 20, which is a semiconductor laser (LD) shown in FIG.
1 and a light source member that generates monochromatic diffused light such as an LED, and an optical member 21 in which a convex lens 2, a pinhole 3, and a beam splitter 4 are integrated. FIG. 4 shows a manufacturing process of the optical member 21.
First, as shown in FIG. 4A, an uneven pattern of a plurality of diffraction gratings constituting a beam splitter 32 is arranged on a silicon (Si) wafer (hereinafter simply referred to as a wafer) 31 by a known electron beam drawing method. Formed.

The method of forming the concavo-convex pattern of the diffraction grating 32 by a known electron beam drawing method will be described. First, a photoresist is applied on the wafer 31 and then the photoresist is diffracted by an electron beam exposure apparatus. A two-dimensional pattern of the grid 32 is drawn. Next, the photoresist is removed through an etching process and a plating process, and the diffraction grating 32 is formed on the surface of the wafer 31.
Is formed.

When the uneven pattern of the diffraction grating 32 is formed on the surface of the wafer 31 in this manner, then, FIG.
As shown in (c), nickel (N
i) is plated to form a father 33 to which the concave / convex pattern of the wafer 31 is transferred. Then FIG.
As shown in (c) and (d), nickel is plated on the father 33 to form a mother 34 to which the pattern of the unevenness of the father 33 is transferred. Next, as shown in FIGS. 4D and 4E, nickel is plated on the mother 34 to form a stamper 35 on which the concavo-convex pattern of the mother 34 is transferred.

Next, as shown in FIGS. 4F and 4G,
The stamper 35 and the lens mold 36 are attached to a molding machine, and a resin of a lens material is injected into the lens mold 36 and molded, thereby forming the lens 37 on which the concave / convex pattern (32) of the stamper 35 (Ni) is transferred. To form In addition,
At this time, in order to position the lens 37 in the circumferential direction, a part of the lens mold 36 is formed in a convex shape in the circumferential direction, so that a concave positioning key is formed in a part of the lens 37 in the circumferential direction. 37a are formed. Finally, as shown in FIG. 4H, a pinhole film 38 is formed by sputtering a metal or the like on the surface of the lens 37 to form a thin film.

Therefore, according to such a manufacturing method, an optical element in which the lens 37, the beam splitter 32 and the pinhole film 38 are integrated as shown in FIG. 5 can be realized. Alternatively, as shown in FIG.
The beam splitter 32 and the pinhole film 38 may be integrated with the lens 37 as a separate member. Further, as shown in FIG. 7, the lens 37 and the pinhole film 38 may be integrated by using the beam splitter 32 as a separate member, and as shown in FIG. And the beam splitter 32 may be integrated. Here, the diameter of the pinhole is shown in FIG.
A desired beam shape can be realized by forming a circle, that is, b = a, or an oval, that is, b> a as shown in FIG.

FIG. 10 shows a method of manufacturing a Fresnel lens as a second embodiment. As is well known, a plurality of annular convex lens patterns are formed on the Fresnel lens,
One annular pattern is formed stepwise. Therefore, in the second embodiment, first, as shown in FIG. 10A, the silicon wafer 4 is formed by a known electron beam drawing method.
A plurality of annular Fresnel patterns 42 are arranged and formed on each of the plurality of annular Fresnel patterns 42.
Note that the step-like pattern can be formed by controlling the intensity of the electron beam.

As described above, the silicon (Si) wafer 41
Next, as shown in FIGS. 10B and 10C, nickel (Ni) is plated on the Fresnel pattern 42 to form the Fresnel pattern 42, as in the first embodiment. A father 43 to which the pattern 42 has been transferred is formed. Next, FIG.
As shown in (d), nickel is plated on the father 43 to form a mother 44 to which the Fresnel pattern 42 of the father 43 is transferred. Next, as shown in FIGS. 10D and 10E, nickel is plated on the mother 44 to form a stamper 45 on which the Fresnel pattern 42 of the mother 44 is transferred.

Next, as shown in FIGS. 10F and 10G, the stamper 45 and the lens mold 46 are attached to a molding machine, and a resin of a lens material is injected into the lens mold 46 and molded. Lens 4 on which the Fresnel pattern 42 is transferred as the concave / convex pattern of the stamper 45
7 is formed. Therefore, according to such a manufacturing method, by performing the process shown in FIG. 10 once, the Fresnel lens 47 in which each of the annular patterns is stepped and in which the plurality of annular Fresnel patterns 42 are formed is manufactured. be able to.

[0032]

As described above, according to the first aspect of the present invention, since the beam splitter and the pinhole are integrated by using the electron beam drawing apparatus, it can be manufactured at low cost. According to the second aspect, since the pinhole is formed by applying a pinhole film to the surface of the convex lens, and the convex lens and the pinhole are integrated,
It can be manufactured at low cost. According to the third aspect, the beam splitter and the convex lens are integrated by using the electron beam drawing apparatus, and further, the beam splitter and the convex lens are integrated with the pinhole, so that the manufacturing can be performed at low cost. . According to the fourth aspect, the optical element in which the diffraction grating is formed on the surface of the convex lens is formed by the electron beam drawing apparatus, so that it can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an optical card to which a first embodiment of an optical element according to the present invention is applied.

FIG. 2 is a configuration diagram illustrating a monochromatic light generating device that generates monochromatic diffracted light with respect to the optical card of FIG. 1;

FIG. 3 is a configuration diagram showing an optical element according to the present invention.

FIG. 4 is an explanatory view showing a manufacturing process of the optical element of FIG. 3;

FIG. 5 is a side view showing the optical element shown in FIGS. 3 and 4;

FIG. 6 is a side view showing a modified example of the optical element of the first embodiment.

FIG. 7 is a side view showing another modified example of the optical element of the first embodiment.

FIG. 8 is a side view showing still another modified example of the optical element according to the first embodiment.

FIG. 9 is an explanatory diagram illustrating a shape of a pinhole in the optical element according to the first embodiment.

FIG. 10 is an explanatory diagram showing a manufacturing process of a Fresnel lens which is an optical element according to the second embodiment.

FIG. 11 is a configuration diagram showing a monochromatic light generator as a conventional optical element.

FIG. 12 is an explanatory view showing a manufacturing process of a Fresnel lens as another conventional optical element.

[Explanation of symbols]

 32 Beam splitter (diffraction grating) 35, 45 Stamper 36, 46 Lens mold 37 Convex lens 37a Positioning member 38 Pinhole film 42 Fresnel pattern 47 Fresnel lens

Continuing from the front page (72) Inventor Koichiro Nishikawa 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside of Victor Company of Japan (72) Inventor Naoyuki Nakagawa 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Japan Victor Co. (72) Inventor Akiya Suehiro 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Japan F-term (reference) 2H043 AE02 AE14 AE21 2H049 AA03 AA04 AA33 AA37 AA40 AA63 AA64 2K009 BB11 CC14 DD04 EE00 5D119 AA38 BA02 JA64 NA05

Claims (7)

[Claims] 1. An optical element which condenses monochromatic diffused light by a convex lens, restricts an irradiation range by a pinhole, and diffracts a plurality of beams by a beam splitter. Forming the beam splitter by duplicating the diffraction grating pattern, forming the pinhole by applying a pinhole film on the surface of the beam splitter, and integrating the beam splitter and the pinhole. An optical element characterized by the above-mentioned. 2. A method for manufacturing an optical element, comprising: condensing monochromatic diffused light by a convex lens, restricting an irradiation range by a pinhole, and diffracting a plurality of beams by a beam splitter. Forming a pattern, forming the beam splitter by duplicating the diffraction grating pattern, forming the pinhole by applying a pinhole film on the surface of the beam splitter, and forming the beam splitter with the beam splitter. Integrating the pinholes. A method for manufacturing an optical element, comprising: 3. An optical element, wherein monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and diffracted into a plurality of beams by a beam splitter. A pinhole film is coated on the surface of the convex lens. An optical element characterized in that the pinhole is formed by doing so to integrate the convex lens and the pinhole. 4. A method for manufacturing an optical element, wherein monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and diffracted into a plurality of beams by a beam splitter. Forming the pinhole by applying a film to integrate the convex lens and the pinhole. A method for manufacturing an optical element, comprising: 5. An optical element wherein monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and is diffracted into a plurality of beams by a beam splitter. An optical element, wherein a stamper of the beam splitter is formed by forming a grating pattern and duplicating the diffraction grating pattern, and the beam splitter and the convex lens are formed integrally by the stamper and a lens mold. 6. A method for manufacturing an optical element, wherein monochromatic diffused light is condensed by a convex lens, its irradiation range is limited by a pinhole, and diffracted into a plurality of beams by a beam splitter. Forming a diffraction grating pattern of the splitter; forming a stamper of the beam splitter by duplicating the diffraction grating pattern; and forming the beam splitter and the convex lens integrally with the stamper and a lens mold. A method for manufacturing an optical element, comprising: 7. A method of manufacturing an optical element in which a diffraction grating is formed on a surface of a convex lens, wherein a diffraction grating pattern is formed by an electron beam drawing apparatus, and the diffraction grating pattern is duplicated to form a stamper of the diffraction grating. And a step of forming the diffraction grating on the surface of the convex lens using the stamper and a lens mold.