JPH06265722A - Wavelength variable type interference optical filter and its production and wavelength variable type interference optical filter device - Google Patents

Abstract

PURPOSE:To provide the wavelength variable type interference optical filter which is the interference optical filter of a narrow band for selecting a wavelength by separating the specific wavelength component of incident light and can arbitrarily select the wavelength without depending on a polarization plane. CONSTITUTION:Multilayered films 3 are constituted by vapor deposition on a substrate 2. These multilayered films 3 consist of lower multilayered films 31, cavity layers 32 and upper multilayered films 33. The upper and lower film layers 31, 33 are respectively constituted by alternately laminating high- refractive index film layers 31H, 33H and low-refractive index film layers 31L, 33L. The wavelength lambda, i.e., film thickness, is continuously changed in the x-axis direction of the substrate 2 in such a manner that all the wavelengths attain lambda/4n (n is a refractive index) in correspondence to the transmission wavelength lambda. The selected wavelength is eventually changed continuously according to the incident position of light if the filter is formed in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a narrow band wavelength tunable interference optical filter used for optical communication, optical measurement, optical information processing, etc., and depends on the plane of polarization whose transmission wavelength can be continuously changed. The present invention relates to a variable wavelength interference light filter, a method of manufacturing the same, and a variable wavelength interference light filter device.

[0002]

2. Description of the Related Art Conventionally, a narrow band optical filter having a dielectric multilayer film has been used as a variable wavelength type filter for continuously changing the wavelength in a narrow band optical filter. Such an optical filter is disclosed in, for example, "Laser & Optics Guide II", Kino Melles Griot Co., Ltd., PP11-25 to 11-29 "Interference filter", and has a high refractive material such as ZnS on a substrate. And Na ₃ AlF
A low refractive index material such as ₆ is alternately multilayer-coated with an optical thickness of exactly 1/4 wavelength. Here, when the transmission wavelength is λ and the refractive index of each layer is n, the optical thickness is represented by λ / 4n. A narrow band optical filter can be realized by forming such a multilayer coating layer on the substrate.

In this state, the transmission wavelength of the interference light filter is a constant wavelength, which is defined by the optical thickness of the filter. However, as shown in "Optical amplifier and its application" supervised by Hideki Ishige, Ohmsha, Ltd., published on May 30, 1992, pp. 146-148, etc., the incident light to the above-mentioned multilayer film type narrow band filter is The transmission wavelength can be continuously changed by changing the angle of. FIG. 12 shows a state in which light from a light source (not shown) is applied to the narrow band optical filter 102 via the optical fiber 100 and the collimator lens 101. Then, the transmitted light is focused lens 103.
It is focused by and is incident on the optical fiber 104 for receiving light. Here, the incident angle of the light beam on the interference light filter 102 is changed from the vertical state shown by the solid line in the drawing to a small angle θ,
For example, the transmission wavelength λ can be continuously changed by changing it within a range of about 0 ° to 10 °, as shown in FIG. At this time, the full width at half maximum does not change much as shown in FIG.

[0004]

However, as shown in FIG. 13, the transmission center wavelength differs depending on the polarization component (S wave, P wave), and if the inclination angle is 10 ° or more, the difference cannot be ignored. Grows to. Further, the transmission band width (full width at half maximum) of this interference light filter also differs depending on the polarization components (S wave, P wave), and as shown in FIG. 14, the P wave greatly changes depending on the inclination angle θ. In addition, the transmittance also changes depending on the inclination angle θ and decreases with the angle.

Further, when the light beam is made to enter the interference light filter perpendicularly (tilt angle θ = 0 °), the light is reflected to the light source side. Therefore, there is a problem in that it is necessary to take measures for avoiding the influence, for example, avoiding use in the vicinity of 0 ° and inserting an optical isolator. As described above, when the transmission wavelength is continuously changed by using the conventional interference light filter, there are many limitations in use and there is a drawback that it depends on the plane of polarization.

The present invention has been made in view of such conventional problems, and it is possible to continuously change the transmission wavelength without depending on the polarization and without rotating the interference optical filter. It is an object of the present invention to provide a narrow-band variable wavelength interference optical filter, a manufacturing method thereof, and a variable wavelength interference optical filter device using the same.

[0007]

A wavelength tunable interference light filter according to the invention of claim 1 of the present application is a polarization plane independent wavelength tunable interference light which continuously changes light transmitted in a predetermined wavelength range. A filter, which is a substrate formed of a substance that transmits light in a usable wavelength range, and a multilayer formed of a substance formed on the substrate and having a high light transmittance that transmits light of a predetermined wavelength range The vapor deposition material film is provided, and the optical thickness of the multilayer vapor deposition material film is configured to continuously change along a predetermined direction of the substrate. It is characterized in that the wavelength of the transmitted light is changed by changing the wavelength along a predetermined direction of the substrate.

In the variable wavelength interference light filter according to the second aspect of the present invention, the film thickness d of each layer of the multilayer vapor deposition material film is such that the vapor deposition material film has a refractive index n and a transmission wavelength at that position is λ. Then, the film thickness is continuously changed so that d = λ / 4n.

In the variable wavelength interference optical filter according to the invention of claim 3 of the present application, the multilayer vapor deposition material film of the variable wavelength interference optical filter is a first vapor deposition material film having a first refractive index n ₁ . It is characterized in that it is constituted by alternately laminating a vapor deposition material film having a _second refractive index n ₂ having a lower refractive index.

In the variable wavelength interference light filter according to the invention of claim 4 of the present application, the vapor deposition material film is such that a cavity layer having a film thickness d of λ / 2n (n is a refractive index) is inserted between the multilayer films. It is characterized by being configured.

In the variable wavelength interference optical filter according to the invention of claim 5 of the present application, a multilayer vapor deposition material film is defined, where x is the position of the substrate in the predetermined direction and λ (x) is the transmission center wavelength at that position. The film thickness d (x) and the refractive index n (x) of the layer satisfy the formulas (1) and (2).

In the variable wavelength interference optical filter according to the invention of claim 6 of the present application, the variable wavelength interference optical filter is configured as a substrate on a rectangular plate, and the position in the longitudinal direction is x. It is characterized in that the thickness of the vapor deposition material film is continuously changed along its longitudinal direction.

The variable wavelength interference optical filter according to the invention of claim 7 of the present application is characterized in that the optical filter is formed on a disk-shaped substrate.

A variable wavelength interference optical filter device according to the invention of claim 8 of the present application makes the light from the variable wavelength interference optical filter according to any one of claims 1 to 6 parallel light. The first collimator is disposed between the first collimator and the second collimator, which is disposed so as to face the first collimator and focuses the light beam, and the optical thickness of the variable wavelength interference light filter. And a moving means for moving the wavelength tunable interference light filter in the direction in which the wavelength is changed.

A variable wavelength interference optical filter device according to a ninth aspect of the present invention is any one of the first to fifth and seventh aspects.
The variable wavelength interference light filter described in paragraph (1), a first collimator that collimates light from a light source, and a second collimator that is arranged to face the first collimator and that condenses a light beam, And a rotating unit which is arranged between the first and second collimators and which rotates the variable wavelength interference light filter.

According to a tenth aspect of the present invention, the substrate is arranged in the vacuum layer, the substrate is arranged at a predetermined angle with respect to the same film thickness surface of the evaporation source, and the material of the evaporation film is changed to form a multilayer evaporation material film. Is a method of manufacturing a wavelength tunable interference light filter, characterized in that

According to the invention of claims 11 to 13 of the present application, the substrate is disposed on the inner surface of the rotary dome which is provided in the vacuum layer and one surface of which is open, and the rotary dome is rotated at a predetermined speed, A first evaporation source having a first index of refraction and a second evaporation source having a second index of refraction are placed in a vacuum chamber, the substrate is tilted, and / or a predetermined distance from the center axis of rotation of the rotating dome. A variable wavelength interference optical filter manufacturing method is characterized in that evaporation sources are alternately vaporized while being separated by a distance, and vapor deposition is performed until a predetermined film thickness distribution is obtained.

[0018]

According to the present invention having such characteristics, the multilayer wavelength tunable interference optical filter is constructed by continuously changing the film thickness of the multilayer vapor deposition material film according to the transmission wavelength.
Therefore, the light selection characteristic changes depending on the light irradiation position according to the changing direction of the film thickness. In this case, the wavelength continuously changes even if the irradiation position of light is changed, but the full width at half maximum or the like does not change, and a characteristic that does not depend on the plane of polarization is obtained.

Further, according to the invention of claims 10 to 13, the substrate is tilted in the vacuum chamber, and the distance from the evaporation source to the surface of the substrate is changed so that the film thickness in a predetermined direction on the substrate is increased. Of the wavelength tunable interference light filter by vapor-depositing a multilayer film so that the wavelength changes continuously.

[0020]

1 is a diagram showing the construction of a polarization plane independent wavelength tunable interference optical filter according to a first embodiment of the present invention. The wavelength tunable interference light filter 1 according to the present embodiment is configured by depositing a substance in multiple layers on a substrate 2 such as glass or silicon. The substrate 2 is made of a material having a high light transmittance in the wavelength range used, and a dielectric or semiconductor is used. In this embodiment, quartz glass is used. On top of this substrate 2, a multi-layer film 3 of vapor deposition material, dielectric, semiconductor or the like having a high light transmittance at the wavelength used is vapor deposited. Here, the multilayer film 3 is assumed to be formed of a lower multilayer film 31, a cavity layer 32 and an upper multilayer film 33 as shown in the figure. An antireflection film 4 is formed on the lower surface of the substrate 2 by vapor deposition. The antireflection film is made of, for example, SiO ₂ , Ti.
Although a two-layer film of O ₂ is used, it is also possible to use only one of them.

Here, the substance used as a vapor deposition material for the multilayer film 3 and the antireflection film 4 is, for example, SiO ₂ (refractive index n =
1.46), Ta ₂ O ₅ (n = 2.15), Si (n = 3.46) and A
l ₂ O ₃ , Si ₂ N ₄ , Mg F or the like is used. Further, in this embodiment, the multilayer film 3 is formed by alternately laminating a low refractive index film and a high refractive index film. Here, the film thickness d, the transmission wavelength λ, and the refractive index n are set to have the following relationships. λ = 4nd (3) That is, each layer has an optical thickness of λ / 4. The low-refractive index films and the high-refractive index films are alternately stacked to reduce the full width at half maximum (FWHM) of the transmittance peak.

In the wavelength tunable interference light filter 1 according to the present embodiment, since the transmission wavelength and the film thickness have the relationship of the expression (3), the substrate 2 is an elongated plate-like substrate,
The transmission wavelength λ is made different by continuously changing the optical thickness of the upper multilayer film 3. Then, the transmission wavelength of the variable wavelength interference light filter 1 is set to λ _a to λ _c (λ _a
<Λ _c ), and the transmission wavelength at the center point (x = x _b ) is λ _b . The upper and lower multilayer films 31 and 33 are a first vapor deposition material film having a first refractive index n _{1 and} a second vapor deposition material film having a lower refractive index than the first vapor deposition material film, respectively.
And second vapor deposition material films having a refractive index of n ₂ are alternately laminated. That is, an enlarged view of the circular portion of FIG.
As shown in (c), each film thickness is continuously changed. In FIG. 1C, the lower multilayer film 31 has a low refractive index film 31L, a high refractive index film 31H, and an upper multilayer film 33.
The high-refractive index film is 33H and the low-refractive index film is 33L. Then, the transmission wavelength of the end portion x _a on the x-axis of the filter of FIG. 1A is set so that the above formula (3) holds for the low refractive index film and the high refractive index film with respect to λ _a . . Also x _b , x _c
Transmission wavelength lambda _b at its wavelength lambda _b against lambda _c, lambda _c
The film thickness is set so that the equation (3) is satisfied by. The film thickness during that time is also set so that the wavelength changes linearly. Thus, each thickness of the layer is located on the x-axis x _a ~x _c
The film thickness increases continuously as the film thickness increases in the positive direction of the x-axis.

For example, λ _a is 1540 nm, λ _c is 1560 nm, λ _b
Is 1550 nm, and for example, the first refractive index n ₁ is 2.15 of TiO 2.
_2, the second refractive index n ₂ is assumed to be laminated alternately and Si O ₂ of 1.46, the upper and lower low refractive index film 31
L and 33L have _a film thickness d of 263.7 nm at the left end (x = x _a ),
At the right end (x = x _c ), the film thickness is 267.1 nm. When TiO ₂ having a refractive index n of 2.15 is used as the high refractive index films 31H and 33H, the film thickness of the high refractive index films 31H and 33H is x.
= X _a is 179 nm, and x = x _c is 181.4 nm. When Si having a refractive index n of 3.46 is used as the high refractive index films 31H and 33H, the film thickness of the high refractive index films 31H and 33H is x.
= X _a is 111.7 nm, and x = x _c is 112.7 nm.

Here, assuming that the change in film thickness in the x-axis direction is a function d (x) of x, the wavelength λ is a function λ (x) of x, and the refractive index is also a variable n (x) of x, these The relationship is expressed by equations (1) and (2). Where x ₀ is an arbitrary position,
For example, the position of x = x _a . A is a constant.

In this embodiment, the upper and lower multilayer films 3
Although the optical thickness is controlled by controlling the film thicknesses of 1 and 33, the film thickness should be the same, and the refractive index should be changed along the x-axis direction of the substrate to form an optical filter. Is also possible. Further, it is not necessary to continuously change the optical thickness on the same straight line, and the optical thickness such as film thickness and refractive index may be changed along an arbitrary line of the substrate.

[0026] The low refractive index film 31L on the substrate 2 of quartz glass, Si O ₂ as 33L, the high refractive index film 31H, using a Ti O ₂ as 33H are alternately stacked,
In a single-cavity filter having a central wavelength of 1550 nm, a narrow band filter having a full width at half maximum (FWHM) of 1 nm or less was realized when the upper and lower multilayer films 3 were 32 layers or more. Also, on the substrate 2 of quartz glass, Si
In the filter having a single cavity structure in which O ₂ and Si are stacked, a narrow band filter having a full width at half maximum (FWHM) of 1 nm or less can be realized by stacking 24 layers including the upper and lower multilayer films 3. As the difference in refractive index between the high-refractive index film and the low-refractive index film increases, a narrow band filter can be realized with a smaller number of film layers.

FIG. 2 shows the change of the transmission wavelength λ with respect to the incident position x of the light, the full width at half maximum, and the change of the transmittance with respect to the variable wavelength interference light filter of this embodiment. Even if the incident position x is changed in the formula (1) to change the transmission wavelength λ linearly, the full width at half maximum and the transmittance do not change depending on the position of the x-axis and are constant values. It is shown. Further, there is no difference in the polarization plane of the incident light, and a narrow band optical filter that does not depend on the polarization plane can be realized.

In the above-mentioned embodiments, the variable wavelength interference optical filter having a single cavity structure is shown, but a filter having a multi-cavity structure having a plurality of such cavity layers may be used. For example, a tunable interference optical filter having a double-cavity structure in which a cavity layer is further formed on the upper multilayer film 33 having the single-cavity structure and the multilayer film is formed on the upper layer film 33 may be configured. In this case, as shown in FIG. 3, the wavelength selectivity can be improved even if the number of multilayer films is reduced. In the figure, m indicates the change in the number of cavities and the wavelength selection characteristic when the same number of multilayer films are used. As is clear from this figure, the wavelength selection characteristic improves as the number of cavities increases.

Now, as shown in FIG. 4, such a wavelength tunable interference optical filter is used by irradiating one end of the optical filter with light, for example, white light, and separating the spectral component of the desired wavelength. In FIG. 4, light is incident on the variable wavelength interference light filter via the optical fiber 11 and the lens 12, and light transmitted through the condenser lens 13 and the optical fiber 14 is received. And this optical filter 1 is x
It is assumed that the wavelength λ selected is changed by moving in the axial direction. Here, if the wavelength tunable interference light filter 1 is slightly tilted as shown in the figure, the light reflected from the front surface of the wavelength tunable interference light filter 1 will not be reflected as it is to the light source side, but to the light source side. The adverse effect can be avoided. It is necessary that this tilt angle be within a range that does not have polarization dependency, for example, 10 ° or less.

FIG. 5 shows a manual variable wavelength interference type interference optical filter device in which a single wavelength light is separated from incident light by using this variable wavelength interference type optical filter and the split wavelength is continuously changed. It is a perspective view which shows the specific example of. In the figure, the base 21 is a frame having a U-shaped cross section, and a collimating linker 22 is arranged on a pedestal inside the frame.
The collimator linker 22 is a component for outputting the light incident from the optical fiber 23 as parallel light. Then, the light incident from the optical fiber 23 is incident on the variable wavelength interference light filters 1A and 1B described above. As described above, the wavelength tunable interference light filters 1A and 1B are respectively tilted at a predetermined angle with respect to the incident light, and the irradiation positions thereof are continuously changed by the adjusters 24 and 26. Two adjacent adjusters 24 and 2 here
A rack and pinion system 6 rotates the knobs to precisely move the wavelength tunable interference optical filters 1A and 1B independently in the x direction in the drawing. This moving position is adjusted by the scales 25 and 27 provided on the adjuster.
For example, it is possible to read accurately with an accuracy of about 10 μm. An output optical fiber 29 is connected to a position facing the collimator linker 22 via a collimator linker 28 on the pedestal. Here, the collimator linkers 22 and 28 are first and second collimators for collimating the light from the light source and condensing the light beams, respectively, and the adjusters 24 and 26 are variable wavelength interference light filters on the x-axis. It constitutes a moving means for moving in the direction.

In this way, the light incident from the optical fiber 23 is transmitted through the wavelength tunable interference light filters 1A and 1B via the collimator linker 22 and is again collimated linker 28.
Is output from the optical fiber 29 via the. Even if the light incident from the optical fiber 23 has a spectrum over a wide wavelength as shown in FIG. 6 (a), this wavelength tunable interference optical filter allows a specific wavelength as shown in FIG. 6 (b). Only the light is selected and is emitted from the optical fiber 29. The selected wavelength can be continuously changed by the adjusters 24 and 26. Here, by switching the filters to be used sequentially by using the two adjusters and the optical filters, it is possible to widen the range of change of the wavelength and improve the width of the selected wavelength in the variable wavelength interference optical filter device as a whole. For example, select the wavelength of variable wavelength interference light filter 1A at 1500 nm
~ 1520nm, 1B shall be selected as 1520nm ~ 1540nm. Then, the relationship between the position and the wavelength is clearly indicated on the scale that the light of the wavelength is selected when it is incident on the optical fiber 23 in advance by using a light source having a known wavelength and the output thereof is obtained. By calibrating at a large number of rotary positions of the knob in this way, it is possible to select an arbitrary wavelength based on this scale even if a light source with an unknown incident wavelength is used.

In this embodiment, the position is manually adjusted by the adjusters 24 and 26, but it goes without saying that the transmission position of the interference light filter may be changed electrically using a motor. Nor. Further, in this embodiment, the width of the selected wavelength is improved by switching the used wavelength by using the two variable wavelength interference light filters, but it goes without saying that a larger number of filters may be used. . Further, if a plurality of filters having the same characteristics are arranged in parallel and moved in the same direction so that the central wavelengths thereof are always matched, the wavelength selectivity can be improved without using the multi-cavity structure.

Although the filter has a rectangular plate filter in the above-described embodiment, a circular filter may be used. Figure 7 shows a disk-shaped substrate 4
2 shows a disc-shaped variable wavelength interference light filter 41 in which a multilayer film 43 and a reflective film 44 are formed on the surface 2. Also in this case, each film thickness is continuously changed in proportion to the position in the x-axis direction in FIG. By doing this, Fig. 8 (a)
As shown in (c) to (c), the transmission wavelength is proportional to cos θ when the position is represented by the angle θ with the origin of the x-axis as the center. Therefore, when the circular filter is rotated, it changes continuously as shown in the figure. Also in this case, the full width at half maximum and the transmittance are constant irrespective of the rotation angle (cos θ or θ) as in the above-described embodiment.

FIG. 9 is a perspective view showing a usage state of such a circular wavelength tunable interference light filter. In this figure, as in the case of the use example of FIG. 4, the light incident via the optical fiber 11 is incident on the wavelength tunable interference light filter 41 as parallel light via the collimator lens 12. The transmitted light is received by the optical fiber 14 via the condenser lens 13. Here, the wavelength tunable interference optical filter 41 is rotated in the direction of the arrow using a rotating means (not shown) such as a motor or crank type knob and a speed reduction mechanism. Then, the wavelength is selected according to the rotation angle. In this case, the wavelength linearized in proportion to cos θ is selected instead of the rotation angle θ. Therefore, if the rotation angle and the selected wavelength are measured in advance, the desired wavelength can be selected.

As described above, if the variable wavelength interference light filter has a circular shape and the thickness of the multilayer film 43 is continuously changed depending on the position in the x-axis direction as shown in FIG. 7A, The wavelength range can be selected by rotating the optical filter between half circles, ie 180 °. Therefore, two circular variable wavelength interference optical filters having different selected wavelength ranges are bonded together as shown in FIG.
It can also be used as A and 41B. In this case, if the selection wavelengths are made different from each other, it is not necessary to switch the two optical filters as shown in FIG. 5, and a wide range of wavelength selection characteristics can be obtained. Further, as shown in FIG. 10B, a larger number of variable wavelength interference light filters 41A to 41A.
It is also possible to configure using 41D.

Further, in the above-mentioned circular wavelength tunable interference light filter, the film thickness of the multilayer vapor deposition material film is continuously changed depending on the position in the x-axis direction, but it corresponds to the angle θ on a specific radius. It is also possible to continuously change the film thickness. In this case, the wavelength characteristic corresponding to the rotation angle θ can be obtained.

Next, a method of manufacturing the filter used in each of the above-described embodiments will be described. In the present embodiment, it is necessary to continuously change the film thickness of the multilayer film 3 of the filter 1 according to the position of the x axis. A manufacturing method for forming a filter having such a film thickness will be described with reference to FIG. In FIG. 11A, reference numeral 51 is a vacuum tank for vacuum vapor deposition, and on the bottom surface thereof, a vapor deposition material 52 serving as an evaporation source, and in the above-described embodiment, SiO ₂ , TiO ₂ or Si is arranged.
A parabolic rotary dome 53 having an open lower surface is provided on the upper portion of the vacuum chamber 51, and is rotated at a constant speed in the arrow direction. Then, a circular substrate 2 is attached to a constant radius position on this inner surface.

Here, the mounting angle of this substrate is set to the rotary dome 5.
3 is not attached along the inner surface of the rotary dome 3, but is inclined with respect to the inner surface of the rotary dome by a predetermined angle α as shown in FIG. 11B. Further, when the film thickness is made uniform, the vapor deposition substance 52 is arranged at the center of the vacuum chamber 51, but in this embodiment, that position is arranged at a position separated from the center by a certain distance L. In this way, the film thickness can be controlled by the temperature and time of vapor deposition, but by appropriately setting the angle α and the position L of the substrate, the film thickness change of the vapor deposition substance can be controlled. Thus, the high refractive index film and the low refractive index film are deposited alternately. By doing so, the distance from the vapor deposition material 52 continuously changes according to the vertical position (x axis) of the substrate as shown in FIG. 1, so that the film thickness also corresponds to the distance of the evaporation source or the like by vapor deposition for a certain time. And will change continuously. In this way, by sequentially switching the vapor deposition material 52 to SiO ₂ and TiO _2, etc., a filter having a multilayer vapor deposition material can be constructed. In this case, the circular wavelength tunable interference optical filter shown in FIG. 7 can be constructed as it is, and the rectangular plate-like interference optical filter shown in FIG. 7 can be formed by cutting it into a rectangular shape along the x-axis. A variable wavelength interference light filter can be configured.

In this embodiment, the substrate is attached to the rotary dome to obtain a desired film thickness. However, the substrate is arranged at a predetermined angle with respect to the same film thickness surface having the same distance from the evaporation source substance. It is also possible to sequentially stack vapor deposition materials having a high refractive index and a low refractive index and vapor deposit them. In this case, the film thickness distribution can be controlled by changing the tilt angle α and the distance from the vapor deposition source.

In the present embodiment, the substrate is tilted and attached to the rotary dome 53, and the vapor deposition material 52 is arranged at a position separated from the center of the vacuum chamber 51 by a certain distance L. However, the substrate is tilted and attached, or The vapor deposition material 52 may be disposed at a position separated from the center of the vacuum chamber 51 by a certain distance L, and only one of them may be performed. Also in this case, the film thickness distribution can be controlled by appropriately setting either the inclination angle α or the distance L from the vapor deposition source.

[0041]

As described in detail above, the wavelength tunable interference optical filter according to the present invention is capable of linearly changing the irradiation position of light without rotating the wavelength tunable interference optical filter, and thus the transmission wavelength is changed. Can be continuously changed. Also, the transmission wavelength differs only depending on the incident position, and the transmittance does not change depending on the plane of polarization of the P wave and S wave.
The same transmittance is obtained for waves. Furthermore, the full width at half maximum, which is the light selection characteristic, does not change depending on the light irradiation position.
An excellent effect that it can be a constant value is obtained. That is, the full width at half maximum and the light transmittance can be kept constant without changing the plane of polarization, and only the wavelength can be continuously changed.

In the eighth and ninth aspects of the invention, the wavelength tunable interference optical filter is moved by the moving means or the rotating means to continuously change the irradiation position of the light beam to the wavelength tunable interference optical filter. Thus, the light of a specific wavelength can be selected from the light of the light source.

Further, according to the invention of claims 11 to 13, it is possible to manufacture a wavelength tunable interference optical filter having a desired film thickness distribution by mounting the substrate while being inclined with respect to the vapor deposition source and performing vapor deposition. .

[Brief description of drawings]

FIG. 1A is a cross-sectional view showing a configuration of a variable wavelength interference optical filter having a single cavity structure according to an embodiment of the present invention, and FIG. 1B is a graph showing a change in transmittance on the x axis. (C) is an enlarged sectional view of the circular portion of (a).

FIG. 2 is a graph showing changes in the transmission wavelength, the full width at half maximum, and the transmittance with respect to the incident position in this example.

FIG. 3 is a graph showing wavelength selection characteristics with respect to the number of cavity layers.

FIG. 4 is a schematic diagram showing a usage state of the variable wavelength interference light filter according to the present embodiment.

FIG. 5 is a perspective view showing a variable wavelength interference optical filter device using the variable wavelength interference optical filter according to the present embodiment.

FIG. 6 is a graph showing spectrum changes of incident light and emitted light to the variable wavelength interference light filter device of the present embodiment.

7A is a diagram showing a configuration of a variable wavelength interference optical filter according to a second exemplary embodiment of the present invention, and FIG. 7B is a graph showing a change in transmittance thereof.

FIG. 8 is a graph showing changes in the transmission wavelength, the full width at half maximum, and the transmittance with respect to the rotation angle of the wavelength tunable interference light filter according to the second embodiment of the present invention.

FIG. 9 is a schematic view showing a usage state of a variable wavelength interference optical filter according to a second embodiment of the present invention.

FIG. 10A is a front view showing a state in which two circular optical filters according to the second embodiment are bonded together, and FIG. 10B is configured by bonding four different wavelength tunable interference optical filters. It is a front view showing an example of use.

11A is a schematic view showing a manufacturing process of the variable wavelength interference optical filter according to the present embodiment, and FIG. 11B is a view showing a mounting angle of the substrate with respect to the rotary dome.

FIG. 12 is a schematic view showing a usage state when changing a transmission wavelength of a conventional interference light filter.

FIG. 13 is a graph showing a change in wavelength with respect to an angle of incident light of a conventional interference light filter.

FIG. 14 is a graph showing a change in full width at half maximum when an incident angle of a conventional interference light filter is changed.

[Explanation of symbols]

1, 1A, 1B, 41, 41A, 41B, 41C, 41
D Wavelength tunable interference light filter 2,42 Substrate 3,43 Multilayer film 4,44 Antireflection film 11,14,23,29 Optical fiber 12,13 Lens 22,28 Collimator linker 24,26 Adjuster 25,27 Scale 31 Lower multilayer film 32 Cavity layer 33 Upper multilayer film 31L, 33L Low refractive index film 31H, 33H High refractive index film 51 Vacuum layer 52 Vapor deposition material 53 Rotating dome

Claims (13)

[Claims] 1. A polarization plane independent wavelength tunable interference optical filter that continuously changes light transmitted in a predetermined wavelength range, the sub filter being formed of a substance that transmits light in a usable wavelength range. A straight and a multilayer vapor deposition material film formed on the substrate and formed of a material having a high light transmittance for transmitting light having a wavelength in a predetermined range, wherein the optical thickness of the multilayer vapor deposition material film is: The substrate is configured to continuously change along a predetermined direction of the substrate, and the wavelength of the transmitted light is changed by changing the irradiation position of the incident light on the optical filter along the predetermined direction of the substrate. A variable wavelength interference optical filter characterized in that 2. The film thickness d of each layer of the multilayer vapor deposition material film is:
2. The film thickness is continuously changed so that d = λ / 4n, where n is the refractive index of the vapor deposition material film and λ is the transmission wavelength at that position. Wavelength tunable interference light filter. 3. The multilayer vapor deposition material film of the wavelength tunable interference light filter comprises: a first vapor deposition material film having a first refractive index n ₁ ;
3. The wavelength tunable interference light filter according to claim 2, wherein the wavelength tunable interference light filter is configured by alternately laminating a vapor deposition material film having a _second refractive index n ₂ having a refractive index lower than that. 4. The vapor deposition material film is configured by inserting a cavity layer having a film thickness d of λ / 2n (n is a refractive index) between the multilayer films. Wavelength tunable interference light filter. 5. When the position of the substrate in a predetermined direction is x and the transmission center wavelength at that position is λ (x), the film thickness d (x) of the multilayer vapor deposition material film and the refractive index of the layer are defined. The wavelength tunable interference optical filter according to claim 1, wherein n (x) satisfies the following expressions (1) and (2). [Equation 1] 6. The tunable interference light filter is constructed on a rectangular plate-like substrate, the position of which is x in the longitudinal direction, and the film thickness of the vapor deposition material film is defined along the longitudinal direction. 6. The wavelength tunable interference optical filter according to claim 5, wherein the thickness is continuously changed. 7. The variable wavelength interference optical filter according to claim 5, wherein the optical filter is formed on a disk-shaped substrate. 8. The variable wavelength interference light filter according to claim 1, a first collimator that collimates light from a light source into parallel light, and a first collimator that faces the first collimator. A second collimator for arranging and condensing a light beam; and a wavelength tunable interference optical filter disposed between the first and second collimators in a changing direction of the optical thickness of the wavelength tunable interference optical filter. A wavelength tunable interference optical filter device, comprising: 9. The wavelength tunable interference light filter according to claim 1, a first collimator that collimates light from a light source into parallel light, and a first collimator that faces the first collimator. A second collimator for condensing a light beam, and a rotating means arranged between the first and second collimators for rotating the wavelength tunable interference optical filter. A variable wavelength interference optical filter device characterized by: 10. A substrate is disposed in a vacuum layer, the substrate is disposed at a predetermined angle with respect to the same film thickness surface of an evaporation source, the material of the evaporation film is changed, and multilayer evaporation material films are laminated and evaporated. A method of manufacturing a wavelength tunable interference light filter, comprising: 11. A substrate is provided in a vacuum dome, one surface of which is open, and a substrate is arranged at a predetermined angle with respect to the inner surface of the rotating dome, the rotating dome is rotated at a predetermined speed, and a first refraction is performed. A first evaporation source having a refractive index and a second evaporation source having a second refractive index are arranged in a vacuum chamber on a rotation center axis of the rotary dome, and the evaporation sources are alternately evaporated to form a predetermined film. A method of manufacturing a wavelength tunable interference light filter, characterized in that it is formed by vapor deposition until it has a thickness distribution. 12. A first evaporation source having a first refractive index, wherein a substrate is provided on an inner surface of a rotary dome which is provided in a vacuum layer and one surface of which is open, and the rotary dome is rotated at a predetermined speed. A second evaporation source having a second refractive index is arranged in a vacuum chamber at a predetermined distance from the center axis of rotation of the rotary dome, and the evaporation sources are alternately evaporated until a predetermined film thickness distribution is obtained. A method of manufacturing a wavelength tunable interference light filter, characterized in that it is formed by vapor deposition. 13. A substrate is disposed in a vacuum dome, one surface of which is open to the inside of a rotary dome, the substrate being inclined at a predetermined angle from the inside of the dome, and the rotary dome being rotated at a predetermined speed to produce a first refraction. A first evaporation source having a refractive index and a second evaporation source having a second refractive index are arranged in a vacuum chamber at a predetermined distance from the central axis of rotation of the rotary dome, and the evaporation sources are alternately evaporated. A method of manufacturing a wavelength tunable interference light filter, comprising: vapor deposition until a predetermined film thickness distribution is obtained.