JP3501833B2 - Optical device and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device and a method for manufacturing the same.

[0002]

2. Description of the Related Art As an optical device such as a lens, a device manufactured by various physical and chemical methods instead of a conventional polishing method has been proposed and put into practical use. For example, a photoresist layer is provided on a transparent glass substrate, a circular shape or an elliptical shape is patterned on this by a photolithography method, the patterned photoresist layer is heated above the glass transition point, and the thermal flow of the photoresist layer is performed. There is known an optical device that is formed into a convex curved surface shape by the action of surface tension and uses this convex curved surface shape as a “refractive surface”, and is transparent to the photoresist formed in the convex curved surface shape and transparent. It has also been proposed to form a refracting surface as the surface shape of the transparent substrate itself by etching the surface of the substrate and engraving the convex curved surface shape of the photoresist as the surface shape of the photoresist on the transparent substrate (Japanese Patent Laid-Open Publication No. HEI 5). -1
73003).

The refraction surface as described above can be formed not only on one surface of the transparent substrate but also on both surfaces thereof. By combining the refraction surfaces formed on both surfaces of the transparent substrate into one unit lens, a wider range of lenses can be obtained. Function can be realized.

However, when the corresponding refraction surfaces are formed on both surfaces of the transparent substrate to realize the lens function, the refraction surface formed on one surface of the transparent substrate and the refraction surface formed on the other surface of the transparent substrate. If the positional correspondence of the above, that is, "optical axis alignment" between the refracting surfaces is not performed accurately, a lens having desired optical performance cannot be realized.

When forming refraction surfaces on both sides of a transparent substrate,
It is not always easy to accurately align the refracting surfaces formed on each surface with each other. In addition, if a good refracting surface can be formed on one surface of the transparent substrate but a good refracting surface cannot be formed on the other surface, it is a "defective product" as an optical device.
Will be. For this reason, it has been difficult to improve the production yield of optical devices having refractive surfaces on both sides.

As one of the methods for solving such a problem, a transparent substrate is divided into two, a refracting surface is formed on one surface of each transparent substrate, and these two transparent substrates are refracted from each other. A method of aligning and integrating by “adhesion” is considered.

According to this method, good refraction surfaces can be combined with each other, and the refraction surfaces on both sides can be well aligned with each other. However, the adhesive agent interposed in the adhesion portion affects the optical performance of the optical device. There is a risk of adverse effects, and depending on the environment in which the optical device is used, there is a problem that the transparent substrates are separated from each other due to deterioration of the adhesive portion.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a high manufacturing yield, a high accuracy of alignment between corresponding refracting surfaces, and an excellent environment resistance. It is intended to provide a novel optical device (claims 3 to 6). Another object of the present invention is to provide a method for manufacturing the optical device ( claim 1,
2 ).

[0009]

The "optical device manufacturing method" of the present invention includes a "first transparent substrate having a desired surface shape formed on one surface and a second transparent substrate having a desired surface shape formed on one surface".
The transparent substrate and the other transparent surface are bonded together to form an integrated optical device. " First
The "desired surface shape" formed on the transparent substrate and the "desired surface shape" formed on the second transparent substrate may be the same as or different from each other.

The optical device manufacturing method according to claim 1,
A "low-alkali or non-alkali glass substrate" is used as the first transparent substrate, and a "high -alkali glass substrate" is used as the second transparent substrate.
It is characterized in that the first and second transparent substrates are aligned by using the "glass substrate of potassium " and the corresponding surface shapes are aligned with each other, and then bonded by "anodic bonding" described later .

In this case, the first or second transparent substrate
Bonding can be performed by forming a thin film of a material containing alkali mobile ions suitable for anodic bonding, or a SiO ₂ film or a wet oxide film of Si film on a smooth surface to be bonded. 2).

The "optical device" of the present invention is the above-mentioned claim.
Manufacturing by the optical device manufacturing method according to Item 1 or 2.
An optical device (claim 3) .

In the optical device according to the third aspect of the present invention, the surface shape formed on the first and / or the second transparent substrate is, for example, "the surface shape of the photoresist" as in the prior art described above. , The surface shape of a material different from that of the transparent substrate may be formed.
May be formed as the surface shape of the transparent substrate itself ”( Claim 4 ).

The optical device according to claim 3 or 4 ,
The desired surface shape formed on the first and second transparent substrates is a “convex or concave refracting surface”, and the optical axes of the refracting surface of the first transparent substrate and the refracting surface of the second transparent substrate are aligned. It can also be realized as a "microlens" of the configuration ( contract
Requirement 5 ) Further, by providing a plurality of refracting surfaces formed on the first and second transparent substrates in an array arrangement,
It can also be realized as a "microlens array" ( claim 6 ).

Of course, in constructing the optical device of the present invention, the desired surface shape formed on the first and / or second transparent substrate is not limited to the refraction surface described above, and is a one-dimensional or two-dimensional Fresnel lens. The shape may be a shape that realizes a grating or a microprism.

[0016]

As described above, in the optical device manufacturing method according to the present invention, the "transparent substrates having a desired surface shape properly formed on one surface" are aligned and bonded.
The "anodic bonding" in the manufacturing method according to claim 1 utilizes the difference in the alkali content of the glass plates constituting the first and second transparent substrates to be bonded to move the movable ions inside. A space charge layer is generated at the interface, and a large electrostatic attractive force is generated by the space charge layer. As a result, the bonding method utilizes the chemical bond generated at the interface.

When a " low alkali or non-alkali" glass substrate is used as the first transparent substrate and a " high alkali " glass substrate is used as the second transparent substrate, the second transparent substrate is obtained. Has a relatively high amount of “alkali ions” such as Na + ions, relative to the first transparent substrate.

Therefore, while the first and second transparent substrates are in contact with each other on their smooth surfaces, a strong electric field is applied from the second transparent substrate side toward the first transparent substrate side, When the first and second transparent substrates were heated to a high temperature of about 400 degrees, "alkali ions" moved from the second transparent substrate to the first transparent substrate due to the action of thermal energy and electric field, and moved. Ions are fixedly received in the first transparent substrate.

When the "migration of alkali ions" occurs in this way, a state of "ion rich" is produced in the first transparent substrate at the interface between the first transparent substrate and the second transparent substrate, compared with the normal state. In the second transparent substrate, a state of “ion deficiency” occurs compared to the normal state. Therefore, the first transparent substrate has a positive charge due to the received alkali ions inside the substrate, and the second transparent substrate has a “negative charge due to alkali ion deficiency” inside the substrate. The transparent substrate of 2 is extremely strongly chemically bonded by the "electrostatic attraction" of the space charge layer.

When carrying out the optical device manufacturing method according to the first aspect of the present invention as in the optical device manufacturing method according to the second aspect, "a smooth surface of the first or second transparent substrate to be bonded is to be formed. , Forming a thin film of a material containing alkali mobile ions suitable for anodic bonding, or forming a SiO ₂ film or a wet oxide film of a Si film to perform bonding, thereby promoting the anodic bonding. You can

Here, as a reference example of bonding, "high
"Hot bonding" will be explained.
Gug is a joining method that utilizes optical contact and chemical reaction. Clean glass surfaces are extremely active, and bringing these clean "mirror-like" glass surfaces into contact gives strong adhesion at room temperature. This phenomenon is called optical contact. The heat treatment increases the adhesive strength of the optical contact. The effect of this heat treatment is explained by the following chemical reaction.

That is, the first and second transparent substrates are made of glass or the like containing SiO ₂ , and when these mutually smooth surfaces are heated by interposing "monomolecular layer" of H ₂ O. Under high temperature conditions, the oxygen bonding layer on the substrate surface softens,
Since it is in a molten state, “H ₂ O” of the monomolecular layer is polarized into “H” and “O—H”, and “H” is bonded to “—Si—O—” to form “Si—OH”. Is generated. At this time, "-Si
A dangling bond is generated from "-O-Si-".

Next, "OH" reacts with "Si-OH", and a dangling bond of "-Si-O" is formed by a dehydration reaction. Then, "-Si-" and "-Si-O" are combined to form "Si-O-Si". Furthermore, "S
i-OH "and from the" HO-Si ", similarly dehydration" _{H 2} O "is removed, it is binding of the" Si-O-Si ". At this time, “H ₂ O” generated by the dehydration reaction is dissipated from the joint portion by diffusion at the interface. In this way, the first
And the second transparent substrate is bonded.

After the above-mentioned "high temperature bonding" , a strong electric field may be applied to the bonded portion at an appropriate high temperature as in the anodic bonding. By doing so, the bonding strength can be further increased by the movement of H + ions.

[0025]

EXAMPLES Specific examples will be described below. Figure 1
[FIG. 3] is a diagram for explaining one example of the optical device manufacturing method according to claim 1. The first transparent substrate 10 shown in FIG. 1 (a) is a “low-alkali glass or non-alkali glass”, and one surface (lower surface in the figure) is a smooth surface and the other surface is , Alignment mark 11 and a series of convex curved surface shapes 11A, 11B ,. ． Are formed. The convex shapes 11A, 11B ,. ． Are arranged in a two-dimensional array in this example.

The second transparent substrate 20 shown in FIG. 1 (b) is a "highly alkaline glass", and one surface (lower surface in the figure) is a smooth surface, and the other surface has a position. The alignment mark 21 and a series of convex curved surface shapes 21A, 21B ,. ． ．
Are formed. Convex shapes 21A, 21B ,. ． Is
They are arranged in a two-dimensional array, and the arrangement state corresponds to the arrangement state of the convex shape 11A and the like on the first transparent substrate 10. The convex shapes 11A, 11B ,. ． , 21A,
22B ,. ． Is the size of the microlens (diameter: about 1 mm or less).

FIG. 1C shows a first transparent substrate 10 and a second transparent substrate 10.
The transparent substrates 20 are aligned and aligned with each other on their smooth surfaces. The "positioning" is performed using the positioning marks 11 and 21. That is, the alignment mark 11 is a "cross-shaped mark" as shown in FIG. 1D, and is formed of a metal thin film. Mark 2
Reference numeral 1 is a mark that is one size larger than the cross mark 11 and has a “cross-shaped mark removed”, and is formed of a metal thin film. These marks 11 and 21 are publicly known marks commonly called "dragonfly".

The alignment is performed by making the mark 11 fit within the "cross-shaped cutout portion" of the mark 21. Such alignment is achieved by the transparent substrates 10 and 2
0 at two points (for example, diagonal points on the diagonal line) or more, the convex surface shapes 11A, 11B ,. ． And the corresponding convex shapes 21A, 21B ,. ． The mutual alignment of is realized.

The convex shapes 11A, 11B ,. ． , 21A,
21B ,. ． ． Are refracting surfaces each having a positive refracting power, and convex shapes 11A and 21A, 11B and 21
B ,. ． As described above, the refracting surfaces corresponding to each other form a pair to form a convex lens. The above-mentioned alignment is to realize the optical axis alignment of "the refraction surfaces corresponding to each other" constituting such a convex lens.

When the alignment is realized, as shown in FIG. 1 (e), the transparent substrates 10 and 20 stacked on each other are
An electric field is applied by the high voltage DC power supply 3. First and second
The transparent substrates 10 and 20 are metallized (sputtered film and Au-plated film) on one end of the surface (the surface on which the refraction surface is formed), and electrodes are formed on this metallized portion. An electric field was applied by connecting to a DC power supply 3. A power supply voltage of 750 to 1000 V was suitable.

At this time, most of the electric field acts on the portion of the joint having a thickness of several tens of μm, and the electric field strength is 10
^{It is 7} to 10 ⁸ V / m. Incidentally, the experiment was conducted using the first and second transparent substrates 10 and 20 each having a thickness of 0.5 mm, one having a thickness of 1 mm and the other having a thickness of 0.5 mm. The electric field acts from the side of the second transparent substrate 20 toward the side of the first transparent substrate 10, that is, from the side having a high alkali ion concentration to the side having a low concentration.

In this state, the first and second transparent substrates 10,
When 20 is heated to about 400 degrees, the first and second transparent substrates 10,
20 is firmly joined and integrated. A few minutes was sufficient for the action time of the electric field. Also, the first or second
2000 Å SiO ₂ film on the surface to be joined of the transparent substrate of
When the film was formed by sputtering to the following thickness, the voltage applied by the power source could be reduced to 30 to 50V.

Thus, a microlens array in which the corresponding refracting surfaces on both sides form convex lenses is obtained. This microlens array has good refraction surfaces formed on both sides, the optical axes thereof are well aligned, and the bonding property is strong and the environmental resistance is strong, and the bonding part does not have an optical adverse effect, and the manufacturing yield is high. Is good. The first transparent substrate 10 may be alkali-free SiO ₂ glass as the low-alkali glass.

The second transparent substrate 20 is made of highly alkaline glass and has a small ionic radius, such as monovalent positive ions such as Li, Na and K, and divalent positive ions such as Pb, Mg, Ca and Cd. Materials having a glass composition such as aluminosilicate or low melting point glass are preferred.

Further, the first and second transparent substrates are made of a material having a substantially constant thermal expansion coefficient over a wide temperature range,
The second transparent substrate is preferably made of a material having an alkaline component and a low volume efficiency. Of course, in order to prevent "strain" after anodic bonding, it is important to remove the "strain" inherent in the material itself.

FIG. 2 is shown above as a reference example of bonding .
Optical device using "high temperature bonding" explained
It is a figure for explaining an example of a manufacturing method . 2A and 2B, the first transparent substrate 100 and the second transparent substrate 200 are aligned with each other with their smooth surfaces aligned (alignment marks 101 and 201 ("marks" similar to those in the example of FIG. 1). )
Is performed).

The first and second transparent substrates 100 and 200 are
Both of them contain SiO _2, and one surface thereof has a convex shape 101A, 101B ,. ． , 201A, 201
B ,. ． An array of refracting surfaces is formed correspondingly, and a monolayer 3 of H ₂ O is formed at the joint portion of smooth surfaces.
00 is interposed. In this state, the transparent substrate 10
Put 0,200 in an oven at 200-400 degrees C,
When heated for 20 to 60 minutes, the above-mentioned "high temperature bonding"
Thereby, the transparent substrates 100 and 200 are joined and integrated.

Thus, a microlens array in which the corresponding refracting surfaces on both sides form a convex lens is obtained. This microlens array has good refraction surfaces formed on both sides, the optical axes thereof are well aligned, and the bonding property is strong and the environmental resistance is strong, and the bonding part does not have an optical adverse effect, and the manufacturing yield is high. Is good. After the high temperature bonding, an electric field is applied to the bonding portion in the oven to strengthen the bonding.

The anodic bonding and the high temperature bonding described above are not only for bonding the first and second transparent substrates, but also as a method for fixing the optical device obtained by the present invention to a support or a holder. Can be used.

For example, in FIG. 3, reference numeral 30 indicates a lens barrel for holding the microlens array manufactured by the method described with reference to FIG. 1. The lens barrel 30 is made of low alkali glass. By doing so, it is possible to fix the transparent substrate 20, which is a highly alkaline glass, by anodic bonding. Further, the lens barrel 30 is made of SiO.
It is also possible to fix the optical device manufactured by the material containing ₂ and manufactured by the method described with reference to FIG. 2 to the lens barrel by “high temperature bonding”.

In the embodiment described above, the first and second
Each of the transparent substrates of No. 1 had a desired convex surface shape as a refracting surface on one surface. Hereinafter, a specific method of forming a convex shape on the surface of the transparent substrate will be described.

The method shown in FIG. 4 is as follows. The substrate indicated by reference numeral 15 is a low-alkali glass, a non-alkali glass, a high-alkali glass, or SiO.
A transparent substrate containing ₂ . A layer of photoresist 16 is formed on the smooth surface of the substrate 15. A state in which this layer is patterned by the photolithography method according to the pattern of the refracting surface to be formed is the state shown in FIG.

In this state, when the patterned layer of the photoresist 16 is heated above the glass transition point, the surface of the photoresist 16 becomes curved due to the action of heat flow and surface tension (FIG. 4 (b)). If the photoresist is transparent, this state may be changed to a state in which "a desired surface shape is formed on one surface of the transparent substrate 15".

Further, in the state of FIG. 4B, the photoresist 16 having a curved surface and the substrate 15 are dry-etched so that the convex shape of the surface of the photoresist 16 is changed to the surface shape of the substrate 15. As "engraving"
As a result, it is possible to obtain the substrate 15 having a desired convex surface shape on one surface (FIG. 4C).

The method shown in FIG. 5 is as follows. The substrate indicated by reference numeral 15 is a low alkali glass, a high alkali glass, or SiO _{2 as in FIG.}
It is a transparent substrate including. A layer 17 of a thermoplastic material such as a resist is formed on the smooth surface of the substrate 15, and an intermediate layer 18 and a thin film of a photoresist 19 are laminated on the layer 17. The intermediate layer 18 is formed by forming a “metal material” such as Cu or Al to a thickness of 2000 to 10000 Å by vacuum deposition or a “non-metal material” such as Si by a vacuum deposition or sputtering to a thickness of 2000 to 5000 Å. It was formed in.

In this state, the thin film of the uppermost photoresist 19 is patterned by the photolithography method according to the pattern of the refracting surface to be formed. FIG. 5A shows a state after patterning.

Then, etching is performed using the thin film of the patterned photoresist 19 as a mask to remove the exposed intermediate layer 18, and as shown in FIG. 5B, the pattern of the patterned photoresist 19 is intermediate. Imaged on layer 18. The etching performed at this time is
The wet etching may be performed when the intermediate layer is made of a metal material, and the wet etching or dry etching may be performed when the intermediate layer is formed of a "non-metal material" such as Si.

Dry etching is performed in this state to engrave the layer of the thermoplastic material 17 in the thickness direction (see FIG. 5).
(C)) Then, after removing the intermediate layer 18 and the thin layer of the photoresist 19, when the layer of the thermoplastic material 17 is heated to the glass transition point or higher, as shown in FIG. The surface of 17 is curved.

Further, the thermoplastic material 1 having a curved surface 1
7 and the substrate 15 are subjected to “anisotropic” dry etching to form the convex shape of the surface of the thermoplastic material 17 on the substrate 1.
By "engraving" as the surface shape of 5, the substrate 15 having a desired convex shape on one surface can be obtained (FIG. 5 (e)).

In the method shown in FIGS. 4 and 5, the surfaces of the photoresist 16 and the thermoplastic material 17 are curved,
In addition to the above-mentioned heating method, a method of applying high pressure isotropically or a method of heating while applying high pressure isotropically is possible. Further, when the surface of the photoresist 16 is curved by the method of FIG. 4 or when the surface of the thermoplastic material 17 is curved by the method of FIG. 5, the photoresist layer and the thermoplastic material layer are “predetermined”. It is also possible to realize the desired aspherical shape by controlling the shape of the curved surface to be formed by irradiating "the light having the light intensity distribution" to give an internal distribution to the fluidity of these substances.

Furthermore, in the method of FIG. 4, between the substrate 15 and the layer of photoresist 16 and, in the method of FIG. 5, between the substrate 15 and the layer of thermoplastic material 17, a “refraction different from the substrate” is observed. Material having a specific ratio "may be formed into a layer by vapor deposition or the like.
It can also be formed as a surface shape of a layer having a material having a refractive index different from.

Although the case where the "desired surface shape" formed on the transparent substrate is a convex curved surface has been described above, the present invention is not limited to this, and the desired surface shape may be concave on the transparent substrate. Curved surfaces may be formed. There are various possible methods for forming the “concave curved surface” on one side of the transparent substrate.
Here is an example:

A photocurable transparent resin 5 is formed on the transparent substrate 15.
0 is applied, and a concave shape is formed on the transparent resin 50 with a mold 60 having a “convex shape corresponding to the desired concave shape” (for example, it can be created by the method described with reference to FIGS. 4 and 5). The resin layer 50 is cured by irradiating the transparent substrate 15 with ultraviolet rays or the like. After that, by removing the mold 60, it is possible to realize a state in which one side of the transparent substrate 15 has a desired concave surface shape. Further, the concave shape of the transparent resin 50 may be engraved on the transparent substrate 15 by performing dry etching from this state.

The state of FIG. 4A or the state of FIG.
If the etching is performed from the above state, the surface shape of the transparent substrate 15 is a “surface shape with a rectangular cross section” in which the side surface is raised.
Since this can be formed, it is also possible to form a grating as the surface shape of the transparent substrate by utilizing this. Alternatively, when a layer of the photoresist 16 is patterned by the method of FIG. 4, if a mask in which the transmitted light intensity distribution changes linearly can be used, it is possible to form a surface shape in which the side surface is an inclined surface. Then, the shape of a micro prism or Fresnel lens can be formed on the surface of the transparent substrate, or a trapezoidal sectional shape (which can be used as an optical low pass filter) can be formed.

Although the embodiment of the microlens array has been described with reference to the embodiments of FIGS. 1 and 2, the microlens array thus obtained may be divided into convex lenses to form microlenses. It is also possible to form a single surface shape on the transparent substrate from the beginning to form a microlens.

[0056]

As described above, according to the present invention, a novel optical device and its manufacturing method can be provided. Contract
According to the inventions of claim 1 and 2, since the first and second transparent substrates having desired desired surface shapes are aligned and bonded, the manufacturing yield is good and the manufacturing cost can be reduced. Is. In addition, since no adhesive is used for joining, positioning is easy and workability is good. According to the second aspect of the invention, anodic bonding can be effectively promoted.

Further , the high temperature bondie described as a reference example
Is an anody used in the invention of claims 1 and 2.
Stronger than transparent bonding on transparent substrate
Easy to mass-produce with no need to apply an electric field
It

The optical devices according to claims 3 to 6 can be manufactured at low cost because they are manufactured by the above-mentioned manufacturing method, there is no optical adverse effect due to the adhesive, and the bonding strength is strong, so that they are excellent in environmental resistance. .

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of the invention according to claim 1;

[Fig. 2] Reference example of bonding method using high temperature bonding
FIG.

FIG. 3 is a perspective view showing the joining method according to the first and second aspects of the present invention.
It is a figure for demonstrating that it can be used for joining of an optical device and a support member.

FIG. 4 is a diagram for explaining an example of a method of forming a desired surface shape as a convex surface on one surface of a transparent substrate.

FIG. 5 is a diagram for explaining another example of a method for forming a desired surface shape as a convex surface on one surface of a transparent substrate.

FIG. 6 is a diagram for explaining an example of a method of forming a desired surface shape as a concave surface on one surface of a transparent substrate.

[Explanation of symbols]

10 First transparent substrate 20 Second transparent substrate 11,21 Position mark 11A, 21A Desired surface shape 3 High voltage DC voltage

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-5-24201 (JP, A) JP-A-4-79272 (JP, A) JP-A-4-371848 (JP, A) JP-A 61- 251802 (JP, A) JP 58-49903 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 3/00 C03C 27/10

Claims (6)

(57) [Claims] 1. A first transparent substrate having a desired surface shape formed on one surface and a second transparent substrate having a desired surface shape formed on one surface are bonded to each other on the other smooth surface, a method of manufacturing an optical device formed by integrating, as the first transparent substrate, using a low-alkali or non-alkali glass substrate, and a second transparent substrate, a glass substrate of high alkaline, These first and second transparent substrates are aligned with each other in their corresponding surface shapes, and then faced from the second transparent substrate side to the first transparent substrate side.
By applying a strong electric field, the first transparent substrate is removed from the second transparent substrate.
Alkali ions migrate to the transparent substrate and the fixed ions are received in the first transparent substrate.
Hold the first transparent substrate and the second transparent substrate together.
At the interface part of the first transparent substrate from the normal state
Ion-rich condition is normal condition with the second transparent substrate
Anode that causes more ion deficiency states
A method for manufacturing an optical device, which comprises bonding by quick bonding . 2. The optical device manufacturing method according to claim 1, wherein a thin film of a material containing alkali mobile ions suitable for anodic bonding is formed on the smooth surface of the first or second transparent substrate to be bonded. Or a wet oxide film of a SiO ₂ film or a Si film is formed and bonded. 3. An optical device manufactured by the optical device manufacturing method according to claim 1 . 4. The optical device according to claim 3 , wherein the surface shape formed on the first and / or second transparent substrate is formed as the surface shape of the first and / or second transparent substrate itself. An optical device characterized by being present. 5. The optical device according to claim 3 , wherein the desired surface shape formed on the first and second transparent substrates is a convex or concave refracting surface, and the refraction of the first transparent substrate is performed. An optical device, which is a microlens, characterized in that an optical axis of the refracting surface of the second transparent substrate is aligned with that of the surface. 6. The optical device according to claim 5 , wherein the first and second transparent substrates have a plurality of refracting surfaces, and the arrangement is an array arrangement. Is an optical device.