JP2010152047A - Optical filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter in which a mirror gap is easily controlled while ensuring reliability. <P>SOLUTION: The optical filter 100 includes: a first substrate 14 and a second substrate 15 which are disposed facing to each other; a first mirror 2A disposed on the first substrate 14; a second mirror 2B disposed on the second substrate 15 and facing to the first mirror 2A; a magnetic force clamp means 25 which fixes the first substrate 14 and the second substrate 15 by magnetic force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical filter.

  An etalon element is known as an optical filter that selects and emits light of a target wavelength. As an etalon element, it has a pair of mirrors facing each other through a gap, and by adjusting the gap with an electrostatic force between a pair of electrodes, for example, the wavelength of transmitted light is selected and set as a target wavelength. A gap-type electrostatic drive type is known (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

In such an etalon element, for example, a mirror and an electrode are formed on the inner surfaces (opposing surfaces) of the first substrate and the second substrate, and a part of them is bonded with the inner surfaces of the substrates facing each other. Let's manufacture. That is, when a part of the substrate is brought into contact with each other, gaps are provided between the mirrors and the electrodes, respectively, and on one of the substrates, the location of the mirror is displaced by the electrostatic force between the electrodes. A movable part is formed so as to change the gap therebetween.
JP 2002-214429 A JP 2003-57438 A JP 2005-62384 A

An etalon element is manufactured by bonding two substrates each provided with a mirror. As a method of bonding, there are a method of fixing with an adhesive or a binder, and a method of fixing by direct bonding such as anodic bonding.
However, it is difficult to secure the accuracy of the gap by a fixing method using an adhesive or a binder. In addition, in the fixing method using surface activated bonding, although the gap control is easy, the adhesive strength varies depending on the state of the bonding surface between the substrates, so that it may be difficult to fix the gap reliably.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an optical filter that facilitates mirror gap control while ensuring reliability.

In order to solve the above problems, an optical filter according to the present invention includes a first substrate and a second substrate disposed to face each other, a first mirror provided on the second substrate side of the first substrate, A second mirror provided on the first substrate side of the second substrate and disposed opposite to the first mirror; and a magnetic force clamping means for fixing the first substrate and the second substrate by magnetic force. It is characterized by.
According to this configuration, since the magnetic clamp means for fixing the first substrate and the second substrate by magnetic force is provided, no adhesive is required, and the first mirror and the second mirror are not used as in the case of using the adhesive. The gap of no longer shifts. Further, since direct bonding such as anodic bonding is not required, the mechanical strength does not change due to the surface condition or the like at the contact portion between the first substrate and the second substrate. Therefore, according to the present invention, it is possible to provide an optical filter capable of easily performing gap control while ensuring reliability.

  The magnetic force clamping means includes a first adsorption member provided on the first substrate and a second adsorption member provided on the second substrate and having an adsorption force with the first adsorption member. Is preferred. According to this configuration, a simple and practical magnetic clamping means can be configured, and an optical filter excellent in manufacturability can be obtained.

  One of the first adsorption member and the second adsorption member may be a magnetic member, and the other may be a metal member that is adsorbed by a magnet. That is, not only the magnetic force adsorption between the magnetic members but also the magnetic force adsorption between the magnetic member and the metal member may be used.

  The metal member may be a metal film formed on the first substrate or the second substrate. With such a configuration, the optical filter can be made thinner than when a magnet or the like is disposed on the outer surface of the substrate.

  It is preferable that the magnetic member is a permanent magnet. As a result, a magnetic force clamping means that can constantly fix the first substrate and the second substrate can be easily obtained.

  In the contact portion between the first substrate and the second substrate, one of the first substrate and the second substrate is provided with a convex portion protruding toward the other substrate, and the other of the first substrate and the second substrate. It is preferable that a concave portion into which the convex portion is inserted is formed on the substrate. With such a configuration, the optical filter can be easily aligned between the first substrate and the second substrate in the substrate surface direction.

  In the contact portion between the first substrate and the second substrate, at least one of the first substrate and the second substrate is preferably formed with a recess having an adhesive provided therein. . According to this structure, it can be set as the optical filter excellent in mechanical strength.

  It is preferable that a part of the concave portion is opened on a side end surface of the optical filter. According to this configuration, the adhesive can be easily arranged. Moreover, it is preferable that the said recessed part is groove shape. According to this configuration, the bonding with the adhesive can be made more reliable.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 and 2 are diagrams showing an optical filter 100 according to an embodiment of the present invention. FIG. 1 is a plan view of the optical filter 100, and FIG. 2 is a position along the line AA 'in FIG. It is a sectional side view of the optical filter 100 in FIG.

The optical filter 100 shown in FIGS. 1 and 2 is an air gap type electrostatic drive type etalon element.
The optical filter 100 includes a first substrate 14 provided with a first mirror 2 </ b> A, a second substrate 15 provided with a second mirror 2 </ b> B, and magnetic force clamping means 25 that sandwich the first substrate 14 and the second substrate 15. And.

The first substrate 14 and the second substrate 15 are plate-like members having a square shape in plan view. The first substrate 14 and the second substrate 15 are made of a material having optical transparency and insulating properties such as glass. Specifically, soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, sodium borosilicate glass, alkali-free glass, and the like are preferably used. If the first substrate 14 and the second substrate 15 are glass substrates, visible light can be used as incident light.
The first substrate 14 and the second substrate 15 may be silicon substrates. In this case, near infrared light can be used as incident light.

  The first substrate 14 is provided with a first mirror 2A and an electrode 16A. The first mirror 2 </ b> A has a circular shape in plan view, and is disposed at the center of an opposing surface (inner surface) 14 </ b> A that faces the second substrate 15. The electrode 16A has an annular shape in plan view, and is provided at a position surrounding the first mirror 2A on the opposing surface 14A.

  On the surface (outer surface) opposite to the facing surface 14A of the first substrate 14, a groove portion 14B having an annular shape in plan view is formed. The groove 14B is formed at a position surrounding the first mirror 2A in plan view. On the other hand, in relation to the electrode 16A, the groove 14B is formed at a position included in the planar region of the electrode 16A.

  The region where the groove 14B of the first substrate 14 is formed has a smaller plate thickness than other regions, and the region where the groove 14B of the first substrate 14 is formed can be elastically deformed. Thereby, the groove part 14B and the site | part which supported the 1st mirror 2A of the planar view circle shape enclosed by the groove part 14B comprise the movable part 13 which moves up and down with the 1st mirror 2A.

  A first adsorption member 25 </ b> A is provided on the outer surface of the first substrate 14. A circular opening 26A corresponding to the outer peripheral shape of the groove 14B is formed at the center of the first suction member 25A. The movable portion 13 of the first substrate 14 is exposed inside the opening 26A. The first suction member 25A constitutes a magnetic force clamping means 25 according to the present invention together with a second suction member 25B described later.

The second substrate 15 is provided with a second mirror 2B and an electrode 16B. A first concave portion 11 and a second concave portion 12 are formed on an opposing surface (inner surface) 15 </ b> A of the second substrate 15 facing the first substrate 14. The first recess 11 is formed in a circular shape in plan view at the center of the facing surface 15A. The second recess 12 is formed at a position that surrounds the first recess 11 in an annular shape with a depth shallower than that of the first recess 11.
The second mirror 2 </ b> B has a circular shape in plan view that is substantially the same as the first mirror 2 </ b> A, and is disposed on the bottom surface of the first recess 11. The electrode 16B has an annular shape that is substantially the same as the electrode 16A, and is disposed on the bottom surface of the second recess 12.

  A second suction member 25 </ b> B is provided on the outer surface of the second substrate 15. A circular opening 26B corresponding to the opening 26A of the first adsorption member 25A is formed at the center of the second adsorption member 25B. The opening 26B, together with the opening 26A of the first adsorption member 25A, serves as a light entrance and exit for the optical filter 100. The second adsorption member 25B constitutes the magnetic force clamping means 25 according to the present invention together with the first adsorption member 25A.

  In the present embodiment, the first mirror 2A and the second mirror 2B are made of a dielectric multilayer film in which a plurality of high refractive index layers and low refractive index layers are alternately stacked. As the first and second mirrors according to the present invention, in addition to the dielectric multilayer film, a silver alloy film containing carbon can also be used.

  When the optical filter 100 is used in the visible light region or the infrared light region, the high refractive index layer of the dielectric multilayer film constituting the first mirror 2A and the second mirror 2B is, for example, titanium oxide, tantalum oxide, niobium oxide, etc. Can be used. As the low refractive index layer, for example, magnesium fluoride, silicon oxide, or the like can be used. Further, when the optical filter 100 is used in the ultraviolet light region, as a material for forming the high refractive index layer, for example, aluminum oxide, hafnium oxide, zirconium oxide, thorium oxide, or the like can be used. The material for forming the low refractive index layer is the same as described above.

  The number and thickness of the high refractive index layer and the low refractive index layer in the dielectric multilayer film are appropriately set based on the required optical characteristics. In general, when a reflective film (mirror) is formed of a dielectric multilayer film, the number of layers required to obtain desired optical characteristics is 12 or more. When an antireflection film is formed of a dielectric multilayer film, The number of layers necessary for obtaining the optical characteristics is about four layers.

  The electrodes 16A and 16B can be formed using a conductive material. The constituent materials of the electrodes 16A and 16B are not particularly limited. For example, metal materials such as Ag, Cu, Al, Au, Pt, Ni, Zn, and Ti, alloys containing them, and resin materials imparted with conductivity (carbon And the like, a conductive semiconductor material (impurity-doped single crystal silicon, polycrystalline silicon, amorphous silicon), a transparent conductive material such as ITO, or the like can be used.

  Further, as shown in FIG. 1, a wiring 17A is connected to the electrode 16A, and a wiring 17B is connected to the electrode 16B. The wiring 17 </ b> A extends from the outer peripheral end of the electrode 16 </ b> A, and the tip thereof reaches the side end face of the optical filter 100. The wiring 17B extends from the outer peripheral end of the electrode 16B to the side opposite to the wiring 17A, and the tip of the wiring 17B reaches the side end surface of the optical filter 100 opposite to the tip of the wiring 17A. A power supply (not shown) is connected to the wiring 17A and the wiring 17B.

  The wiring 17A is preferably arranged in the wiring groove 18A formed in the first substrate 14, and the wiring 17B is arranged in the wiring groove 18B formed in the second substrate 15. preferable. By providing the wiring grooves 18A and 18B in this way, it is possible to prevent the wirings 17A and 17B from interfering with the joint portion between the first substrate 14 and the second substrate 15.

  As shown in FIG. 2, the first substrate 14 and the second substrate 15 are fixed in contact with each other by magnetic force clamping means 25 (first suction member 25A, second suction member 25B) that sandwich them. ing. In the case of the present embodiment, the region on the outer peripheral side of the electrode 16A of the opposing surface 14A on the first substrate 14 and the region on the outer peripheral side of the second recess 12 of the opposing surface 15A on the second substrate 15 are in contact with each other. These contacted regions constitute the contact portion 21.

  In the contact portion 21, recesses 14 </ b> D that open to the facing surface 14 </ b> A are formed at the four corners of the first substrate 14, and recesses 15 </ b> D that open at the facing surface 15 </ b> A are formed at the four corners of the second substrate 15. In each corner of the optical filter 100, the concave portion 14D and the concave portion 15D are provided at positions overlapping each other in plan view, and form one sealed space continuous in the plate thickness direction. And the 1st board | substrate 14 and the 2nd board | substrate 15 are positioned in the plate | board surface direction by the positioning member 20 accommodated in this sealed space.

  Note that an adhesive may be disposed in the recesses 14D and 15D, and the positioning member 20, the first substrate 14, and the second substrate 15 may be fixed with the adhesive. In this case, it is preferable to prevent the adhesive from protruding outside the recesses 14D and 15D. Thereby, it can avoid that the adhesive agent which protruded becomes a cause which reduces the precision of the gaps G1 and G2.

  Each of the first adsorption member 25A and the second adsorption member 25B may be made of a magnetic member, one may be a magnetic member, and the other may be a metal member that is adsorbed by a magnet. Moreover, the shape may be a bulk shape or a sheet shape. When the first suction member 25A and the second suction member 25B are arranged on the outer surfaces of the first substrate 14 and the second substrate 15 as in the present embodiment, it is preferable that the first suction member 25A and the second suction member 25B have a sheet shape. By making the first adsorbing member 25A and the second adsorbing member 25B into a sheet shape, the thickness of the entire optical filter 100 can be reduced, and the region where the adsorbing force acts is widened.

  The magnetic member is not particularly limited as long as it exhibits an attractive force (magnetic force) that can hold the first substrate 14 and the second substrate 15 in contact with each other. That is, it may be a permanent magnet or an electromagnet. However, since the magnetic force clamping means 25 constantly clamps and fixes the first substrate 14 and the second substrate 15, it is preferable to use a permanent magnet that does not require electric power.

  The permanent magnet may be a rare earth magnet, a ferrite magnet, an alnico magnet, or the like, but a rare earth magnet having a strong coercive force (neodymium magnet, samarium cobalt magnet, praseodymium magnet, samarium magnet, etc.) is used. preferable.

  Moreover, as a metal member adsorb | sucked to a magnet, iron and iron alloys (stainless steel etc.) can be mentioned typically. Examples of other metal members include cobalt, nickel, gadolinium, and alloys thereof.

The optical filter 100 of the present embodiment having the above configuration selects light having a wavelength corresponding to the size of the first gap G1 from light incident on the first mirror 2A via the first substrate 14, for example. And can be ejected from the exit surface (outer surface) of the second substrate 15.
More specifically, light that has passed through the first substrate 14 and the first mirror 2A and entered the first gap G1 is reflected a plurality of times between the first mirror 2A and the second mirror 2B. Then, due to the interference effect between the first mirror 2A and the second mirror 2B, light of a specific wavelength corresponding to the size of the first gap G1 is strengthened and selectively transmitted through the second mirror 2B. Light is emitted from the exit surface.

  In the optical filter 100, the wavelength of the extracted light can be controlled by changing the first gap G1. In order to change the first gap G1, a controlled voltage is applied between the electrodes 16A and 16B. An electrostatic force corresponding to the applied voltage is generated between the electrodes 16A and 16B by the voltage application, and the movable portion 13 is deformed by the electrostatic force to displace the first mirror 2A. Thereby, the 1st gap G1 can be controlled to the intended space | interval.

In the optical filter 100 of this embodiment described in detail above, the first substrate 14 and the second substrate 15 are fixed by the attractive force of the magnetic force clamping means 25.
With such a configuration, the first substrate 14 and the second substrate 15 can be fixed in a state in which the surfaces are in direct contact with each other. That is, since it is not necessary to bond the first substrate 14 and the second substrate 15 via an adhesive or the like, it is possible to prevent the gaps G1 and G2 from being uneven due to the non-uniform thickness of the adhesive or the like. can do.
Therefore, the optical filter 100 of the present invention can improve the accuracy of the distance (first gap G1) between the first mirror 2A and the second mirror 2B.

  Moreover, in the optical filter 100 of this embodiment, since the 1st board | substrate 14 and the 2nd board | substrate 15 are fixed by the magnetic force clamp means 25, it is not necessary to join the 1st board | substrate 14 and the 2nd board | substrate 15. FIG. Therefore, unlike in the case of using anodic bonding, the bonding strength does not decrease depending on the surface state of the bonding surface, and an optical filter having excellent reliability can be realized.

  Hereinafter, modifications of the embodiment will be described. In any of the following modifications, it is needless to say that the same effect as that of the above embodiment can be obtained.

(First modification)
FIG. 3 is a cross-sectional view of an optical filter 100A according to a first modification, and corresponds to FIG. 2 in the above embodiment.
The optical filter 100A has a configuration in which the second adsorption member 25B is a metal film formed on the surface of the second substrate 15 on the first substrate 14 side. That is, the first adsorption member 25A is a magnetic member, and the second adsorption member 25B is made of a metal that adsorbs a magnet. The second adsorption member 25B can be a metal film made of, for example, an iron alloy or a cobalt alloy, and a known film formation method such as a sputtering method can be used as the film formation method.

In this example, the case where the metal film second adsorption member 25B is formed on the inner surface of the second substrate 15 has been described. However, the metal film second adsorption member 25B may be formed on the outer surface of the second substrate 15. Good.
Further, instead of the second adsorption member 25B, the first adsorption member 25A may be a metal film. Also in this case, as shown in FIG. 3, the film may be formed on the outer surface of the first substrate 14, or may be formed on the inner surface (opposing surface 14 </ b> A) of the first substrate 14.

By using at least one of the second adsorbing member 25B and the first adsorbing member 25A as a metal film as in this example, a thinner optical filter can be realized.
Although the second adsorption member 25B is formed on the contact surface with the first substrate 14, unlike the adhesive, it can be formed on the substrate with a uniform thickness, so the accuracy of the gaps G1 and G2 is reduced. There is no fear.

(Second modification)
FIG. 3 is a cross-sectional view of an optical filter 100B according to a second modification, and corresponds to FIG. 2 in the above embodiment.
The optical filter 100B includes a solid magnet as the second adsorption member 25B. In the optical filter 100 </ b> A, a plurality of recesses 15 </ b> E are formed in the second substrate 15. The recess 15 </ b> E has a depth in the thickness direction of the second substrate 15 and opens to the outer surface of the second substrate 15. And the 2nd adsorption | suction member 25B which consists of a cylindrical magnet is inserted in the recessed part 15E, for example.

  The shape of the second adsorption member 25B is not particularly limited, and may be a rectangular parallelepiped shape or a cubic shape, or may be a polygonal column shape or a spherical shape. Further, an adhesive may be disposed in the recess 15E, and the second suction member 25B may be fixed to the second substrate 15.

  In the optical filter 100A, the first suction member 25A may be a magnetic member or a metal member that is attracted to a magnet. Further, the first adsorption member 25A may be a solid magnetic member or a metal member, or may be a sheet-like magnetic member. Further, the first adsorption member 25A may be a thin-film metal member.

  In FIG. 3, the second attracting member 25B, which is a solid magnet, is disposed in the recess 15E, but the recess 15E may be formed as necessary. That is, the second adsorption member 25B may be directly placed on or adhered to the outer surface of the second substrate 15. In FIG. 3, the recess 15E is formed on the outer surface of the second substrate 15. However, a recess is formed on the side end surface of the second substrate 15, and the second adsorption member 25B made of a solid magnet is embedded in the recess. But you can. The same applies to the case where the first attracting member 25A is a solid magnet.

  Furthermore, if the form using a solid magnet or a metal member is applied, the structure which used the positioning member 20 shown in FIG. 2 as the 1st adsorption | suction member 25A or the 2nd adsorption | suction member 25B is also employable. In this case, the positioning member 20 may be either a magnetic member or a metal member that is attracted to the magnet, but must be fixed to either the first substrate 14 or the second substrate 15. The fixing method of the positioning member 20 may be fixing by an adhesive or fixing by screwing. Or the fixing method which provides a fixing pin in the outer peripheral surface of the positioning member 20, and engages this fixing pin with the inner wall of the recessed part 14D or the recessed part 15D may be sufficient.

(Third Modification)
FIG. 4 is a cross-sectional view of an optical filter 100C according to a third modification, and corresponds to FIG. 2 in the above embodiment.
The optical filter 100 </ b> C has a configuration in the case where bonding with an adhesive is used in the contact portion 21 between the first substrate 14 and the second substrate 15. In the optical filter 100 </ b> C, a recess 14 </ b> E is formed at a position corresponding to the contact portion 21 on the inner surface of the first substrate 14. An adhesive 24 is provided inside the recess 14E.

  In the optical filter 100C, the inner wall of the recess 14E and the inner surface of the second substrate 15 are bonded by an adhesive 24 provided inside the recess 14E. Thereby, compared with the case where the 1st board | substrate 14 and the 2nd board | substrate 15 are fixed only by the magnetic clamp means 25, a bigger fixed strength can be obtained and the optical filter excellent in mechanical strength can be implement | achieved. .

  In this example, the adhesive 24 is used for the contact portion 21, but the adhesive 24 is disposed in the recess 14 </ b> E and is not applied to the contact surface between the first substrate 14 and the second substrate 15. Therefore, the gaps G1 and G2 are not uneven due to the uneven thickness of the adhesive as in the case where the adhesive is applied to the opposing surfaces of the first substrate 14 and the second substrate 15 to be joined.

In this example, the case where the recess 14E is formed inside the side end surface of the first substrate 14 has been described. However, it is preferable that a part of the recess 14E is open to the side end surface of the first substrate 14. . With such a configuration, after the first substrate 14 and the second substrate 15 are brought into contact with each other and fixed, the adhesive 24 can be poured and bonded from the opening of the recess 14E.
Moreover, it is preferable that the recessed part 14E is the groove shape extended in the surface of the contact part 21. FIG. With such a configuration, the bonding area by the adhesive 24 can be widened, and the bonding strength can be improved.

  In the previous embodiment, as shown in FIG. 1, since the wiring groove 18A and the wiring groove 18B are formed in the first substrate 14 and the second substrate 15, the wiring grooves 18A and 18B are formed as an adhesive. You may utilize as the recessed part 14E in which 24 is arrange | positioned.

The top view of the optical filter which concerns on embodiment. Sectional drawing of the optical filter which concerns on embodiment. The figure which shows the 1st modification of an optical filter. The figure which shows the 2nd modification of an optical filter. The figure which shows the 3rd modification of an optical filter.

Explanation of symbols

  100, 100A, 100B, 100C Optical filter, 2A 1st mirror, 2B 2nd mirror, 14 1st substrate, 15 2nd substrate, 14D, 15D, 14E Concavity, 24 Adhesive, 25 Magnetic clamp means, 25A 1st adsorption Member, 25B second adsorbing member

Claims (8)

A first substrate and a second substrate disposed to face each other;
A first mirror provided on the second substrate side of the first substrate;
A second mirror provided on the first substrate side of the second substrate and disposed opposite to the first mirror;
An optical filter comprising: magnetic force clamping means for fixing the first substrate and the second substrate by magnetic force.   The magnetic force clamping means includes a first adsorption member provided on the first substrate and a second adsorption member provided on the second substrate and having an adsorption force with the first adsorption member. The optical filter according to claim 1.   3. The optical filter according to claim 2, wherein one of the first adsorption member and the second adsorption member is a magnetic member, and the other is a metal member that is adsorbed by a magnet.   The optical filter according to claim 3, wherein the metal member is a metal film formed on the first substrate or the second substrate.   The optical filter according to claim 3 or 4, wherein the magnetic member is a permanent magnet. In the contact portion between the first substrate and the second substrate,
One of the first substrate and the second substrate is provided with a convex portion protruding toward the other substrate, and a concave portion into which the convex portion is inserted is formed in the other substrate. The optical filter according to claim 1, wherein: In the contact portion between the first substrate and the second substrate,
6. The first substrate and the second substrate, respectively, are provided with recesses facing each other, and a positioning member is accommodated inside the recesses facing each other. The optical filter according to claim 1. In the contact portion between the first substrate and the second substrate,
8. The recess according to claim 1, wherein a concave portion provided with an adhesive is formed in at least one of the first substrate and the second substrate. 9. Optical filter.

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