JP2001281443A - Air gap type fabry-perot etalon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems of a conventional air gap type Fabry-Perot etalon which is produced by joining parallel planar transparent substrates with a spacer such that the cost is increased due to an increase in the number of parts, the workability for assembling the structural parts degrades and the improvement in the productivity by a batch process is difficult. SOLUTION: In the air gap type Fabry-Perot etalon having two transparent substrates each having a reflection face on one surface assembled with the reflection faces parallel to and facing each other through a specified gap, each transparent substrate 2 has a use region 5 having a parallel planar structure consisting of specified thickness where light enters and exits in the center part of the reflection face 3 side, and a frame region 6 formed as integrated and protruding along at least two side lines on the edge of the use region and having larger thickness than the thickness of the use region. The upper faces of the frame regions of the two transparent substrates are joined to form one body and to form a gap inside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an air-gap Fabry-Perot etalon used as an optical device such as a spectroscopic element, and more particularly, to a conventional parallel-plate-shaped transparent substrate joined via a spacer. The present invention relates to a simplified configuration of an air-gap Fabry-Perot etalon.

[0002]

2. Description of the Related Art Heretofore, transparent materials such as quartz glass and quartz have been used as optical devices such as spectroscopic devices by forming them in a very thin parallel plate shape. As this type of optical device, there is a Fabry-Perot etalon (spectroscopy element) used for a Fabry-Perot interferometer, for example. The Fabry-Perot etalon uses two mirror-polished reflective surfaces arranged in parallel, and uses multi-beam interference generated when light having a certain wavelength is incident on these two reflective surfaces at an angle close to perpendicular. Optical system. This optical system has a spectral effect in which an incident light beam causes interference while reciprocating on the reflection surface, and light of a specific wavelength is transmitted intensified. There are two types of Fabry-Perot etalons, a solid type shown in FIG. 8 and an air gap type shown in FIG. The solid-type Fabry-Perot etalon shown in FIG. 8 has reflection surfaces 62 and 64 formed by mirror-polishing both surfaces of a very thin transparent substrate 60.
It is what it was. With such a configuration, a spectral effect can be obtained. The air-gap Fabry-Perot etalon shown in FIGS. 9A and 9B is composed of two parallel flat substrates 70 and 71 and two spacers 73 and 73. That is, a reflection film is formed on one surface 70a, 71a of each of the two substrates 70, 71 made of a transparent material to form a reflection surface, and the opposite surfaces 70b, 71b of the two substrates 70, 71 are AR (non-radiation). (Reflection) surface. The two parallel plates are integrally joined using the two spacers 73, 73 in a state where the reflection surfaces 70a, 71a of the two substrates 70, 71 are opposed to each other.
71a are arranged to face each other in parallel with a predetermined gap G therebetween.

The ideal transmission characteristics (resonance characteristics) of both types of Fabry-Perot etalons are that the transmitted light intensity is It, the incident light intensity is Io, the transmittance at the reflecting surface 62 is T1, and the reflecting surface 6 is
4, the reflectance at the reflecting surface 62 is R1, the reflectance at the reflecting surface 64 is R2, the refractive index of the substrate 60 is n, the physical thickness d of the substrate 60, the wavelength λ of light, and the incidence. If the angle is θ, it can be expressed as the following equations (1) and (2). It / Io = T1 · T2 / ｛[1-{(R1) · √ (R2)]} 2 + 4 · {(R1) · {(R2) · [sin (δ / 2)]} 2} (1) δ = 4πnd · cos θ / λ (2) When this is expressed by spectral characteristics, it is as shown in FIG. 10, and there are many resonance peaks of transmittance at certain intervals. You can see that The interval Δλ between the resonance peaks is given by the following equation (3).
Can be obtained by Δλ = λ ＾ 2 / (2nd · cos θ) (3) As is apparent from this equation, the interval between the resonance peaks of the Fabry-Perot etalon, which is a spectroscopic element, is smaller than that of the substrate 60 in the case of the solid type. The thickness is determined by the plate thickness t. In the case of the air gap type, it is determined by the gap width w of the substrate. By the way, the solid-type Fabry-Perot etalon shown in FIG. 8 has a simple structure in which reflection films 62 and 64 are formed on both surfaces of a parallel plate-shaped substrate 60 manufactured using quartz glass or the like. It is more advantageous in terms of price than the air gap type Fabry-Perot etalon. However, since the solid Fabry-Perot etalon utilizes multi-beam interference inside the substrate 60, its temperature characteristic depends on the change in the refractive index of the substrate material, and the etalon characteristic (FSR value) is Easy to fluctuate.

[0004]

On the other hand, the air-gap type Fabry-Perot etalon uses multi-beam interference in the atmosphere (gap G), and thus is not easily affected by temperature. And stable characteristics can be maintained. However, the air gap type Fabry-Perot etalon has a spacer 73 between the two substrates 70 and 71.
Therefore, not only the number of parts is increased by the amount of the spacer 73 and the product cost is increased, but also the alignment work between the parts is difficult as shown in FIG. There is a problem that mass production by processing is impossible. On the other hand, FIGS. 11A and 11B are views showing an example of a method of manufacturing the air gap type etalon of FIG. 9, and the air gap type etalon according to this embodiment has a structure as shown in FIG. The base material 80 of two transparent substrates of the same shape made of a transparent glass material (parallel plate) such as quartz glass
1 is sandwiched and integrated with a spacer plate 81 interposed therebetween such that the reflection surfaces 84 face each other.
As shown in FIG. 1B, it can be manufactured by cutting with a dicing saw or the like along the frame region 83 of the spacer plate 81. Reference numeral 85 denotes a non-reflective surface. The spacer plate 81 has the same outer dimensions as each base material 80 and is made of the same material, and through holes 82 of the same shape are formed on the surface thereof at a predetermined pitch and arrangement by etching or the like. A frame region 83 is located between the through holes 82. After the frame region 83 is cut as shown in FIG. 11B, it becomes the spacer 73 shown in FIG. A reflection surface 84 is formed on one surface of each transparent substrate base material 80 by mirror polishing, formation of a reflection film, or the like. According to this manufacturing method, mass production by batch processing is possible, but since a spacer plate is required in addition to two base materials, the joining surface becomes two layers, so that the manufacturing becomes complicated, and the productivity is increased. Was not always good. The present invention has been made in view of the above, and in an air gap type Fabry-Perot etalon used as an optical device such as a spectroscopic element, two parallel plate-shaped transparent substrate base materials are joined via a spacer plate. It is an object of the present invention to solve the disadvantage of the conventional type constituted by the above-mentioned problem, that is, the deterioration of the workability of assembling the component parts.

[0005]

In order to solve the above-mentioned problems,
The invention according to claim 1 is an air gap type Fabry-Perot etalon in which two transparent substrates each having a reflection surface on one surface are assembled so that the reflection surfaces face each other in parallel with a predetermined gap therebetween. The substrate has a use area of a parallel plate structure having a predetermined thickness for allowing light to enter and exit from the central portion on the reflection surface side, and is integrally provided along at least two sides of the periphery of the use area, and It is characterized in that there is a frame region thicker than the plate thickness of the use region, and a gap is formed inside the two transparent substrates by joining the upper surfaces of the respective frame regions together and integrating them. The invention according to claim 2 is an air gap type Fabry-Perot etalon in which two transparent substrates each having a reflection surface on one surface are assembled so that the reflection surfaces face each other in parallel with a predetermined gap therebetween, wherein the transparent substrate is A use region of a parallel plate structure having a predetermined plate thickness for allowing light to enter and exit from the central portion on the reflection surface side, and the use region is integrally protruded along at least two sides of the periphery of the use region. A parallel plate-shaped transparent plate having a frame region thicker than the region thickness and having a reflective surface on one side on the upper surface of each of the frame regions of one of the transparent substrates is used as a transparent substrate. It is characterized by being joined so as to oppose. The invention according to claim 3 is characterized in that the gap is an airtight space or a non-airtight space.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. 1 (a) and 1 (b) are a perspective view and an AA sectional view showing an external appearance of an overall structure of an air-gap Fabry-Perot etalon according to an embodiment of the present invention. 2 (a), 2 (b) and 2 (c) are a rear view, a sectional view taken along the line BB, and a side view of an etalon piece constituting the air-gap Fabry-Perot etalon of the present invention. This air gap type Fabry-Perot etalon is used for a Fabry-Perot etalon (spectroscopy element) used for a Fabry-Perot interferometer, for example. An air-gap Fabry-Perot etalon (hereinafter simply referred to as an air-gap etalon) 1 of the present invention includes a mirrored reflection surface 3 on one surface and a non-reflection surface (non-reflection film) 4 on the other surface. The two transparent substrates (etalon pieces) 2 having the same shape are assembled so that the reflection surfaces 3 face each other in parallel with a predetermined airtight space (gap) G therebetween. This transparent substrate 2
Has a use region 5 of a parallel plate structure having a predetermined plate thickness d1 for allowing light to enter and exit from the central portion on the reflection surface 3 side, and is integrally provided to protrude along the entire periphery of the use region 5; A frame region 6 having a plate thickness d2 larger than the plate thickness d1 of the use region 5
Having. The air gap type etalon 1 of the present invention
One transparent substrate 2 is integrated by joining upper surfaces 6 a of the frame region 6 to each other. The air-gap etalon 1 according to this embodiment is characterized in that it has a frame region 6 that is integrated along the entire periphery of the reflection surface 3 of the use region 5 and a part of which protrudes. And a projecting length d of a frame region portion protruding from the reflection surface 3 side of the use region 5;
That is, the width W of the gap G is set to a value that can obtain characteristics necessary for use as a Fabry-Perot interferometer. Also,
The thickness d2 of the frame region 6 depends on the size of the target air gap type etalon, the thickness d1 of the use region 5 and the width W of the gap G, the type of the substrate material, the required mechanical strength, Alternatively, an appropriate value is determined in consideration of ease of processing and the like. Air gap type etalon 1 of this embodiment
Is configured such that incident light causes multi-beam interference in an airtight space (gap) G obtained by joining the two transparent substrates 2, so that outside air flows out into the space between the two transparent substrates 2. There is no change in characteristics due to air fluctuations as compared with the type that enters. In addition, since the entire periphery of the use area 5 is reinforced by the frame area 6, the mechanical strength is increased. For example, when the use area 5 is used by being incorporated into an actual machine, the use area 5 is hardly deformed by heat, and Stabilizes.

Next, FIG. 3 is a view showing an example of a method of manufacturing the air gap type etalon shown in FIG. 1. In this embodiment, a large number of rectangles are formed on one surface of a transparent substrate base material 20 in a predetermined arrangement by etching. 1 are prepared by joining two surfaces on which the concave portions 21 are formed, and then cutting along a frame region 22 with a dicing saw or the like, thereby preparing the two shown in FIG. The air gap etalon 1 as described above can be obtained. Next, FIG.
FIG. 4 is a diagram for explaining a method of manufacturing an air gap type etalon including a method of forming a concave portion 21 in the transparent substrate base material 20 shown in FIG. 3. FIG. 4A shows a state in which a metal film 32 such as Cr serving as an etching mask is vapor-deposited on one side of the substrate to a predetermined thickness on a quartz glass substrate 30 constituting a part of the transparent substrate base material 20. After applying a photoresist 34 on the metal film 32, (c) the photoresist 34 is patterned using a photolithography technique. The resist opening 35 formed by this patterning is a place where the use area 5 of the air gap etalon 1 as a finished product is formed. In FIG. 4D, the metal film 32 is anisotropically etched using the patterned photoresist 34 as a mask. In (e), the remaining photoresist 34 is removed by stripping, and in (f), the surface of the quartz glass substrate 30 is wet-etched using the patterned metal film 32 as a mask. In this case, as the etchant used in this case, a mixture of an NH4 F solution and an HF solution at a predetermined ratio is used. After this etching solution is used to etch to a thickness close to the desired thickness (the concave portion 2)
1) Fine adjustment of the plate thickness using a thin etching solution for finishing. If at least the surface of the quartz glass substrate 30 to be etched is polished to a mirror surface in advance, a sufficiently practicable mirror surface can be obtained for the surface after the etching. FIG. 4 (g) shows that the metal film 32 used as an etching mask is peeled off and removed, thereby forming a recess 21 having a use area 5 having a predetermined thickness and a thickness of the recess located at the outer peripheral portion thereof. Transparent substrate base material 2 having thick frame region 22
0 can be formed. Finally, as shown in FIG. 4 (h), the two transparent substrate preforms 20 are overlapped with the recessed portions 21 and the frame regions 22 formed on the respective surfaces aligned with each other, and bonded and integrated with an adhesive, Finally, the joined body of the two transparent substrate base materials 20 is cut by a dicing saw from a cutting line L located at an intermediate position of the frame region 22, so that the individual pieces of the air gap type etalon as shown in FIG. Obtainable. For the non-reflective surface 4, a non-reflective film may be applied at an appropriate time such as after the step (g).

Next, FIGS. 5A and 5B are external perspective views of an air gap type etalon according to another embodiment of the present invention.
And CC sectional view. The air-gap type etalon 1 according to this embodiment is different from the air-gap type etalon 1 shown in FIG. 1 in a configuration having a void (non-hermetic space) 40 penetrating two opposing side surfaces. It is the same as the gap type etalon. Therefore, the same parts are denoted by the same reference numerals. As a procedure for manufacturing this type of air gap type etalon 1, the method shown in FIGS. 3 and 4 can be used, but in order to form the gap 40 exposed at the time of cutting with a dicing saw, Regarding the frame regions 13 and 22 on the side where the void 40 is formed, the cut points by the dicing saw are cut into the respective frame regions 13 and 22.
The position along the edge of each of the frame regions 13 and 22 (the position near the through hole 12 and the concave portion 21 = the cutting line L1 in FIG. 4H) is not the center of the width of 22. That is, the type shown in FIG. 1 and the type shown in FIG. 5 can be arbitrarily manufactured only by changing the cutting position. Next, FIGS. 6 (a) and 6 (b) are an external view and a DD sectional view of an air gap type etalon according to another embodiment of the present invention, which is a modification of the air gap type etalon of FIG. It is an example. This type of air gap type etalon is characterized by a configuration in which a parallel plate-shaped transparent plate 45 is joined and integrated on the upper surface 6a of the frame region 6 of the transparent substrate 2 shown in FIG. One surface of the transparent plate 45 is a reflection surface 46.
And the reflecting surface 46 is the reflecting surface 3 of the other transparent substrate 2.
Assemble to face. The other surface is a non-reflective surface 47. A gap 48 having a predetermined width W is formed between the transparent substrate 2 and the transparent plate 45. When this type of air-gap type etalon is manufactured by the procedure shown in FIGS. 3 and 4, one of the base materials may be a parallel plate base material, and the other procedures are shown in FIGS. The procedure is the same. Therefore, after joining a parallel plate base material (not shown) onto the frame region 22 of the transparent substrate base material 20 shown in FIG.

Next, FIGS. 7A and 7B are an external view and an EE sectional view of an air gap type etalon according to another embodiment of the present invention. It is a modification of a type etalon. This type of air gap type etalon is characterized by a configuration in which a parallel plate-shaped transparent plate 45 is joined and integrated on the upper surface 6a of the frame region 6 of the transparent substrate 2 shown in FIG. One surface of the transparent plate 45 is a reflection surface 46, which is assembled so that the reflection surface 46 faces the reflection surface 3 of the other transparent substrate 2. The other surface is a non-reflective surface (non-reflective film) 47. Therefore, the air gap type etalon shown in FIG. 7 can be manufactured by diverting the procedures shown in FIGS. 3 and 4 as described in the description of the manufacturing method of the air gap etalon in FIG. When manufacturing the air gap type etalon shown in FIG. 7 by diverting the manufacturing method shown in FIGS.
After joining the parallel plate-shaped transparent substrate preform to the transparent substrate preform 20 having the array formed thereon, the cutting line L1 in FIG.
, And a cutting position is selected so as to expose the gap 40 on two opposing side surfaces. As described above, the above-described embodiment is an air gap etalon configured so that incident light causes multi-beam interference in a gap formed between opposed reflection surfaces of each use area of two transparent substrates, Adopted a configuration in which two transparent substrates integrally provided with a frame area corresponding to a spacer were joined along the periphery of the use area, so mass production of air-gap etalons using a manufacturing method suitable for batch processing can do. Alternatively, a parallel plate having a reflecting surface on one side is joined to and integrated with the upper surface of the frame body of one transparent substrate having a frame region corresponding to a spacer along the periphery of the use region, so that a simpler procedure is possible. Thus, mass production of the air gap type etalon becomes possible.

Further, according to the manufacturing method of the present invention, it is possible to form a very thin parallel flat plate constituting a use area with good controllability, and to arrange a frame area having a large thickness on the outer peripheral portion. The mechanical strength is increased, and it is possible to prevent the air gap type etalon from being damaged during processing or during assembly after processing. In addition, according to the air gap type etalon according to the present embodiment, since the air gap type etalon is manufactured using photolithography technology, it can be manufactured at low cost, and the thickness of the air gap type etalon can be controlled and the mirror surface can be processed. The accuracy is sufficiently practical, and a large number of elements can be manufactured at a time with uniform accuracy, and a large number of highly reliable and inexpensive air gap type etalons can be manufactured. In the present embodiment,
As shown in FIG.
Although the front shape of 0 is a quadrangle, it is not necessarily limited to this shape and may be a circle or a polygon other than a quadrangle. Also, the above-described manufacturing method is an example, and FIGS.
The present invention can be applied to all the manufacturing methods manufactured by etching, even if the manufacturing method is not shown in FIG.
Further, the glass material of the air gap type etalon is not limited to quartz glass, but can be formed using various crystal materials or glass materials. As described above, according to the present embodiment, the thickness of the parallel plate portion forming the use region and the thickness of the frame region protruding from the periphery of the use region can be formed with good controllability, so that the accurate gap size can be obtained. Thus, an air-gap Fabry-Perot etalon provided with: In addition, since the frame region having a large thickness is arranged on the outer peripheral portion, the mechanical strength is increased, and it is possible to prevent damage during processing or during assembly after processing. In addition, since it is manufactured using photolithography technology, it can be manufactured at low cost, and the controllability of the plate thickness and the processing accuracy of the mirror surface portion are sufficiently practical. Can be manufactured with uniform accuracy, and a large number of highly reliable and inexpensive air gap type Fabry-Perot etalons can be manufactured.

[0011]

As described above, according to the first aspect of the present invention, the use area of the parallel plate structure having a predetermined plate thickness for allowing light to enter and exit from the central portion on the reflection surface side and at least two of the periphery of the use area are defined. Using two transparent substrates, each of which is integrally protruded along one side and has a frame region thicker than the plate thickness of the use region,
A gap was formed inside by joining and integrating the upper surfaces of the respective frame regions. It is no longer necessary to use individual spacers, one by one, as in the prior art, and mass production becomes possible. Further, even if the thickness of the use area is extremely thin, the mechanical strength can be improved by the frame area, so that the transparent substrate is prevented from being damaged during processing or assembly, and is inexpensive and excellent. An air gap Fabry-Perot etalon having characteristics can be provided. According to the second aspect of the present invention, a parallel plate-shaped transparent plate having a reflective surface on one side is bonded to the upper surface of each frame region of one transparent substrate such that the reflective surface faces the use region of the transparent substrate. Thus, an air gap type Fabry-Perot etalon having a simpler configuration can be provided. Other effects are the same as those of the first aspect. According to the third aspect of the present invention, since the space is an airtight space or a non-airtight space, an air-gap Fabry-Perot etalon having an arbitrary configuration can be selected according to the purpose of use and the like.

[Brief description of the drawings]

1 (a) and 1 (b) are a perspective view and an AA sectional view showing an external appearance of an overall structure of an air gap Fabry-Perot etalon according to an embodiment of the present invention.

FIGS. 2 (a), (b) and (c) are a rear view, a BB sectional view, and a side view of an etalon piece constituting an air gap type Fabry-Perot etalon of the present invention.

FIG. 3 is a diagram showing another example of a method for manufacturing the air gap type Fabry-Perot etalon shown in FIG.

4 (a) to 4 (h) are views for explaining a method of manufacturing an air gap type Fabry-Perot etalon including a method of forming a concave portion in the transparent base material shown in FIG.

FIGS. 5A and 5B are external perspective views of an air-gap Fabry-Perot etalon according to another embodiment of the present invention;
And CC sectional drawing.

6 (a) and 6 (b) are an external view and a DD sectional view of an air-gap Fabry-Perot etalon according to another embodiment of the present invention.

7A and 7B are an external view and an EE cross-sectional view of an air gap Fabry-Perot etalon according to another embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional solid-type Fabry-Perot etalon.

FIGS. 9A and 9B are configuration diagrams of a conventional air-gap Fabry-Perot etalon.

FIG. 10 is a diagram illustrating spectral characteristics of a conventional etalon.

FIGS. 11A and 11B are views showing an example of a conventional method for manufacturing an air gap type Fabry-Perot etalon.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Air gap type Fabry-Perot etalon, 2 Transparent substrate, 3 Reflection surface, 4 Non-reflection surface (Non-reflection film), G Hermetic space (Void) 5 Use area, 6 Frame area, 6a Upper surface, 20 Transparent substrate base material, 21 Recess (groove), 22
Frame area, 30 quartz glass substrate, 32 metal film, 34
Photoresist, 35 resist openings, 40 voids,
45 transparent plate 46 reflective surface, 47 non-reflective surface, 48 void.

Claims (3)

[Claims] 1. An air-gap Fabry-Perot etalon in which two transparent substrates each having a reflection surface on one surface are assembled so that the reflection surfaces face each other in parallel with a predetermined gap therebetween, wherein the transparent substrate is A use region of a parallel plate structure having a predetermined thickness for allowing light to enter and exit from the central portion on the reflection surface side; and a projecting portion integrally protruding along at least two sides of the periphery of the use region, and An air gap type Fabry-Perot comprising a frame region having a thickness greater than a plate thickness, wherein two transparent substrates are joined together by joining the upper surfaces of the respective frame regions to form a gap therein. Etalon. 2. An air-gap Fabry-Perot etalon in which two transparent substrates each having a reflection surface on one surface are assembled so that the reflection surfaces face each other in parallel with a predetermined gap therebetween, wherein the transparent substrate is A use region of a parallel plate structure having a predetermined thickness for allowing light to enter and exit from the central portion on the reflection surface side; and a projecting portion integrally protruding along at least two sides of the periphery of the use region, and A parallel plate-shaped transparent plate having a reflection surface on one side is provided on the upper surface of each of the frame regions of one of the transparent substrates, the reflection surface facing a use region of the transparent substrate. An air-gap Fabry-Perot etalon characterized by being joined together. 3. The air-gap Fabry-Perot etalon according to claim 1, wherein the gap is an airtight space or a non-airtight space.