JPS63241434A - Variable interference device - Google Patents

Abstract

PURPOSE:To perform control stably with high accuracy by controlling the optical path length of a Fabri-Peot interferometer in one-body structure externally by a driving system. CONSTITUTION:The interferometer consisting of light-transmissive substrates 1 and 2 is sandwiched between the electromagnet composed of a magnetic core 5 and a coil 6 and a magnetic body 7. A hole is bored in the magnetic body 7 where light passes. The interferometer and electromagnet are fixed by a holder. Then when a current is supplied to the coil 6, an attractive force is generated between the magnetic core 5 and magnetic body 7. The magnetic body 7 is attracted with the attractive force through the interferometer, which is applied with a force. The substrates 1 and 2 are bent with the force and the distance between reflection films 4 varies. On the other hand, when only one substrate is made thin and easy to bend, the gap between the reference films 4 varies with the current flowing through the coil 6 and the transmission peak wavelength of the interferometer is scanned. Thus, the interferometer is constituted in one-body structure and the substrate is applied with the force based upon an external electromagnetic force to vary the gap between the reflecting films 4, thereby easily controlling the optical path length of the interferometer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a compact spectroscopic device using a Fapley-Perot interferometer.

<Prior Art> Conventionally, many spectroscopic devices using a diffraction grating have been used. This method obtains the necessary eye-color light by mechanically rotating a diffraction grating, and while it provides high resolution, it requires high precision in positioning each optical element and also increases the size. It has the following problems. On the other hand, as another type of spectroscopic device, a Fapley-Perot interference device using a piezoelectric element is known. FIG. 6 shows this configuration. This spectroscopic device controls the distance between two opposing reflecting mirrors by expanding and contracting a piezoelectric element, and obtains the necessary monochromatic light from changes in interference characteristics. In this structure,
The distance between the two reflecting mirrors must be controlled with great precision, and it is not easy to control the two piezoelectric elements. ! surrounding area 2
Due to thermal expansion of the holder due to temperature variations, the reflector spacing may vary. The conventional structure described above has a major problem in the accuracy and stability of the interval control of the reflecting mirrors.

<Objective of the Invention> The present invention aims to provide a small variable interference device that can control the optical path length of an interferometer with high precision and stability based on the principle of a Fapley-Perot interferometer, and has a spectroscopic function. purpose.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 shows an enlarged perspective view of an interferometer, which is a main component of an embodiment of the present invention. Transparent substrate 1.1-j spacer 3
Through predetermined intervals? They are facing each other. Reflections are formed on the opposing inner surfaces, creating a hollow structure. Glass, transparent ceramics, or polymer resin is used for the transparent substrate 1.2. The reflective film 4 is made of a metal film or a single-layer or multi-layer dielectric film 751. The spacer 3 and the reflective film 4 are formed by vapor deposition method, sputtering method, and TFICVD.
It is manufactured by a thin film forming method such as the method.

Here, the basic principle of the variable interference device will be explained. Consider a case where light is incident perpendicularly to the substrate surface and there is no phase jump in the light at the reflective film 4. When the distance between the reflective films 4 is t, and the refractive index of the medium between them is n, the Fapley-Perot interference transmittance T(λ) is the wavelength λm expressed by the following equation (1).
maximum every time.

nt Sm=-Cm=x, 2.3-) -u+If the scanning wavelength range is from λ1 to λ2 (however, λ2<2λ1), then the distance t between the reflective films °4 is λλ□/2 n≦ t≦λ2
/2n, only light with wavelength λ-2nt is transmitted. That is, by arbitrarily changing t from λ1/2n to λ2/2n, it is possible to completely transmit only light of any wavelength in the wavelength range from λ175 to λ2. for example,
When the scanning wavelength range is 400 to 750 nm, the interval t between the four reflective films may be controlled to be 200 nm to 375 nm. In this case, since the space between the reflective films 4 is hollow, the refractive index is approximately 1. Strictly speaking, light with a wavelength shorter than λl is also transmitted, so a filter that removes light with a wavelength of less than λl is used, and a light receiving element (not shown) that is insensitive to light with a wavelength of less than λ1 is used. Bye.

FIG. 2 shows a perspective view of an embodiment of the present invention including a drive system. The interferometer composed of a transparent substrate 1.2 is sandwiched between an electromagnet consisting of a magnetic core 5 and a coil 675 and a magnetic body 7. The magnetic body 7 has a hole through which light passes.

A thin sheet-like material with high transmittance such as pure iron or permalloy is suitable for the magnetic material 7. The interferometer and electromagnet are fixed with a holder (not shown).The coil When a current is passed through 6, an attractive force F is generated between the magnetic core 5 and the magnetic body 7. Here, U is the magnetic permeability in vacuum, N is the number of turns in the coil, Itd current, and the area of the S Ii magnetic pole. Q is magnetic resistance. That is, the attractive force is proportional to the square of the current. This attractive force attracts the magnetic body 7 through the interferometer and applies force to the interferometer. When the optical substrate 1.2 is bent, the distance t between the reflective films 4
changes.

The relationship between the distance between the reflective films 4 and the force F applied to the substrate is 1=1.
−αF. Here t. is the distance between the reflective films 4 when no force is applied, and α is the variation of the unit force.

α is a value determined by the thickness and width of the substrate and the distance between the spacers 3, and the value of /j:a increases as the substrate becomes thinner, the width becomes smaller, and the distance between the spacers 3 becomes larger. That is,
Only one of the transparent TIT substrates needs to be made thinner so that it can be easily bent. As shown in FIG. 3, the distance t between the reflective films 4 changes with respect to the current flowing through the coil, and the transmission peak wavelength of the interferometer is scanned.

In this way, the interferometer is constructed in one piece, and by applying force to the substrate using electromagnetic force from the outside and changing the reflection film 40 times, it is very easy to change the optical path length of the interferometer. Just in case. Also, without using any mechanical parts,
Furthermore, since no heavy parts are attached to the interferometer, the interferometer will not be damaged by vibration or shock.

FIG. 4 shows another embodiment of the invention. A magnetic material 7 is adhered to a transparent substrate I. The magnetic body 7 has a hole through which light passes. A magnetic core 5 is fixed at a very small distance (~0.1-a) from the magnetic body 7.

The magnetic body 7 and the magnetic core 5id are not in contact. The coil 6 may be installed at an angle so as not to obstruct the optical path. When current is passed through the coil 6, electromagnetic force is generated in the magnetic core 5, pulling up the magnetic body 7 and bending the transparent substrate 7 into a convex shape. In this embodiment, as the current increases, the distance between the reflective films 4 increases.

FIG. 5 shows still another embodiment of the present invention. Transparent substrate 1
The movable magnetic body 8 is in contact with. The movable magnetic body 8 may be installed so as not to obstruct the optical path, or a hole may be made in the magnetic body 8 to ensure the optical path.

Possible! v] The magnetic body 8 can rotate around a fulcrum 9. The coil 6 is installed at a position where it can absorb the flexible magnetic material 8. At least when no current is flowing through the coil 6, the movable magnetic body 8 and the coil 6 are not in contact. When a current is passed through the coil 6, it attracts the movable magnetic body 8, and the tip of the movable magnetic body 8 applies force to the transparent substrate 1. It is not particularly important that the magnetic body 8 can rotate; it may be fixed and elastic deformation can be used. In this embodiment, the coil 6 and the movable magnetic body 8 can be brought as close as possible, so a large force can be easily obtained. Further, in any of the embodiments, an effective drive system can be constructed by using a combination of permanent magnets.

<Effects of the Invention> According to the present invention, since the optical path length of the integrated Fapley-Perot interferometer is externally controlled by a drive system, it can be controlled with high accuracy and stability, and complex mechanical parts can be controlled. Since the parts that are in contact with the interferometer are lightweight, the interferometer will not be damaged by vibration or shock, and the device will not operate unstable, making it a compact variable interferometer with spectroscopic function. A device can be created.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an interferometer, which is a main component of an embodiment of the present invention. FIG. 2 is a block diagram of a variable interference device showing an embodiment of the present invention. FIG. 3 is a current-wavelength characteristic diagram of the variable interference device shown in FIG. 2. FIG. 4 is a sectional view showing GIFFc according to another embodiment of the present invention. FIG. 5 is a sectional view showing the structure of still another embodiment of the present invention. FIG. 6 is a sectional view of a conventional variable interference device. 1゜2...Transparent substrate, 3...Spacer, 4...
...Reflection film, 5...Magnetic core 6...Coil,
7...Magnetic material agent Patent attorney Sugiyama
Itoshi Koro (1 other person) 1st figure dormitory 2 figure

Claims (1)

[Claims] 1. At least one of the reflectors is transformed into a Fabry-Perot interferometer having a cavity surrounded by two opposing reflectors and a support for supporting the reflectors. A variable interference device characterized in that a displacement means is added to change the interference characteristics by changing the interference characteristics. 2. Using a coil that generates electromagnetic force as a displacement means,
The variable interference device according to claim 1, wherein the interference characteristics are changed by controlling the current or voltage flowing through the coil. 3. The variable interference device according to claim 1 or 2, wherein the displacement means comprises a coil facing each other with an interferometer in between, and a magnetic body that is attracted to the coil and curves at least one of the reflectors. . 4. The variable interference device according to claim 3, wherein a magnetic body is fixed to the interferometer. 5. The variable interference according to claim 1 or 2, wherein the displacement means is arranged in contact with the interferometer and comprises an integrated drive system consisting of a coil and a magnetic body that apply force to at least one of the reflectors. Device.