JP2012189760A - Optical filter, optical filter module, spectrometer, and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration in characteristic of an optical film and prevent attachment between optical films.SOLUTION: An optical filter includes a first substrate 20, a second substrate 30 facing the first substrate 20, a first metal film 40 provided for the first substrate 20, and a second metal film 50 provided for the second substrate 30 and facing the first metal film 40. The first metal film 40 has a reflection characteristic and a transmission characteristic with respect to light of a desired wavelength region. A top surface and a side surface of the first metal film 40 are covered with a dielectric film 41. The dielectric film 41 is formed thicker in a peripheral part of the first metal film 40 than in a light incidence part of the first metal film 40 where the light is incident.

Description

  The present invention relates to an optical filter, an optical filter module, a spectrometer, and an optical device.

An etalon filter is known as an optical filter that emits light of a specific wavelength from incident light. A metal film or a dielectric multilayer film is used as an optical film that functions as a mirror in an etalon filter. This optical film needs to have both reflection characteristics and transmission characteristics, and thin metal (Ag) or a silver alloy has been studied as an effective material for the metal film.
Patent Document 1 discloses an etalon element (variable gap type etalon filter) that selects a light having a wavelength corresponding to a gap dimension by forming a gap by facing two optical films and changing the gap dimension. Has been.

JP 2002-277758 A

When a metal film is used as an optical film in an etalon element or the like, the characteristics of the optical film may deteriorate due to oxidation or sulfuration of the metal film. For example, a thin film of silver and its alloy is effective as a material for an optical film, but has a problem that heat resistance and environmental resistance are inferior. In particular, in the manufacturing process of an etalon filter or the like, since oxidation and sulfurization are promoted under heating such as heat treatment, it is important to prevent deterioration of the characteristics of the optical film.
Furthermore, in the variable gap type etalon element that can change the distance between the optical film, when the pair of optical films facing each other is charged, the optical films are attracted and adhered, and then the adhered state is maintained. The proper gap may not be maintained.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 An optical filter according to this application example includes a first optical film having reflection characteristics and transmission characteristics, and a second optical film disposed opposite to the first optical film via a gap and having reflection characteristics and transmission characteristics. An optical film; a first electrode formed around the first optical film; and a second electrode formed around the second optical film and disposed opposite to the first electrode. At least one of the optical film and the second optical film has a metal film, the surface and side surfaces of the metal film are covered with a dielectric film, and the dielectric film is formed at the peripheral edge of the metal film at the metal film. It is characterized in that it is formed thicker than the light incident part where light enters.

According to this configuration, the dielectric film covers from the upper side to the side surface of the metal film provided in the optical film, and the thickness of the dielectric film is larger than the light incident part where light enters the metal film at the peripheral edge of the metal film. Is formed thick. Thus, since the metal film provided in the optical film is covered with the dielectric film from the upper side to the side surface of the metal film, it is possible to prevent deterioration of characteristics such as oxidation and sulfidation of the metal film.
Further, the optical filter of the application example changes the gap dimension between the first optical film and the second optical film by an electrostatic force generated between the first electrode and the second electrode, and changes the wavelength band corresponding to the gap dimension. You can switch. Since the dielectric film is formed thicker at the peripheral edge of the metal film than the light incident part where light enters the metal film, the first optical film and the second optical film are charged. When the two attract each other, the peripheral end portion formed with a large thickness serves as a stopper, and the first optical film and the second optical film can be prevented from sticking to each other. As described above, this application example realizes an optical filter in which the dielectric film prevents the optical film from being deteriorated in characteristics and can appropriately maintain the gap dimension between the first optical film and the second optical film.

  [Application Example 2] In the optical filter according to the application example, the material of the metal film includes Ag alone, an alloy containing Ag as a main component, Au simple substance, an alloy containing Au as a main component, Cu simple substance, and Cu as a main component. It is desirable that the alloy is any one of the following alloys.

  According to this configuration, the metal simple substance or the metal alloy is effective as a material for an optical film having both light reflection and transmission characteristics.

  Application Example 3 In the optical filter according to the application example described above, the material of the dielectric film is Al oxide film, Al nitride film, Si oxide film, Si nitride film, Ti oxide film, Ti nitride A film, a Ta oxide film, a Ta nitride film, an ITO film, a film of the first group of Mg fluoride films, or a stack of any one oxide film and one nitride film of the first group A membrane is desirable.

  According to this configuration, the dielectric film included in the first group has an effect of preventing contact between the gas that causes oxidation, sulfurization, and the like, and the metal film, and also has heat resistance, and light transmittance. Therefore, it can function as a protective film for the metal film.

  Application Example 4 An optical filter module according to this application example includes the optical filter and a light receiving element that receives light transmitted through the optical filter.

  The optical filter module can be used, for example, as a light receiving unit (including a light receiving optical system and a light receiving element) of a spectroscopic measuring instrument. According to this application example, an optical filter module capable of preventing deterioration of the characteristics of the metal film and appropriately maintaining the gap dimension between the optical films is realized.

  Application Example 5 A spectroscopic measurement device according to this application example is provided based on signal processing based on the optical filter, a light receiving element that receives light transmitted through the optical filter, and a signal obtained from the light receiving element. And a signal processing unit that executes the signal processing.

  According to this application example, it is possible to realize a highly reliable spectroscopic measuring instrument in which the deterioration of the characteristics of the optical film is suppressed and the gap dimension between the optical films can be appropriately maintained. The signal processing unit performs predetermined signal processing based on a signal (light reception signal) obtained from the light receiving element, and measures, for example, a spectrophotometric distribution of the sample. By measuring the spectrophotometric distribution, for example, sample colorimetry, sample component analysis, and the like can be performed.

  Application Example 6 An optical device according to this application example includes the optical filter described above.

  According to this configuration, optical film characteristic deterioration is suppressed, the gap dimension between the optical films can be properly maintained, and highly reliable optical equipment (for example, a detection device for substances such as gas, optical communication application equipment, etc.) Is realized.

The schematic plan view which shows the structure of the variable gap filter of 1st Embodiment. The schematic sectional drawing which follows the AA disconnection of FIG. It is the elements on larger scale which show the 1st metal film in 1st Embodiment, (a) is a schematic plan view, (b) is a schematic sectional drawing in alignment with the BB broken line of the same figure (a). Process drawing explaining the formation method of the 1st metal film and dielectric film of a 1st embodiment. It is an enlarged view which shows the part of the 1st metal film in the variable gap filter of the modification of 1st Embodiment, (a) is a schematic plan view, (b) is the outline which follows the CC disconnection of the figure (a). Sectional drawing. Process drawing explaining the formation method of the 1st metal film and dielectric film in the modification of 1st Embodiment. (A), (b) is a schematic sectional drawing which shows the structure of the 1st optical film in another modification, and the structure of a dielectric film. Explanatory drawing which shows the structure of the optical filter module using the variable gap filter in 2nd Embodiment. The block diagram which shows schematic structure of the food analyzer in 3rd Embodiment. The block diagram which shows schematic structure of the gas detection apparatus which detects the substance in 4th Embodiment. The block diagram which shows the structure of the control system which concerns on the gas detection apparatus in 4th Embodiment. The block diagram which shows schematic structure of the transmitter of the wavelength division multiplexing communication system in 5th Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In the drawings used for the following description, the ratio of dimensions of each member is appropriately changed so that each member has a recognizable size.

(First embodiment)
In the first embodiment, a configuration of a variable gap filter as an optical filter will be described.
FIG. 1 is a schematic plan view showing the configuration of the variable gap filter. FIG. 2 is a schematic sectional view taken along the line AA in FIG. 3 is a partially enlarged view showing the first metal film, FIG. 3 (a) is a schematic plan view, and FIG. 3 (b) is a schematic cross-sectional view taken along the line BB in FIG. 3 (a).

As shown in FIGS. 1 and 2, the variable gap filter 1 includes a first substrate 20 and a second substrate 30, and is, for example, a planar square-shaped optical member having a side of about 10 mm.
The first substrate 20 and the second substrate 30 are formed of a base material that transmits visible light, such as soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass. It is made of various types of glass, quartz, quartz, etc.

  A plasma polymerized film 38 is formed as a bonding film along the outer peripheral edges of the first substrate 20 and the second substrate 30, and the first substrate 20 and the second substrate 30 are interposed through the plasma polymerized film 38. And are joined. Thus, the variable gap filter 1 has a structure in which the first substrate 20 and the second substrate 30 are integrated.

Further, a first metal film 40 as a first optical film and a second metal film 50 as a second optical film are provided between the first substrate 20 and the second substrate 30. In this embodiment, each of the first optical film and the second optical film is composed of a single metal film.
Here, the first metal film 40 is formed on the surface of the first substrate 20 facing the second substrate 30, and the second metal film 50 is formed on the surface of the second substrate 30 facing the first substrate 20. ing. Further, the first metal film 40 and the second metal film 50 are disposed to face each other with a gap interposed therebetween.

Further, a drive electrode for adjusting the dimension of the gap between the first metal film 40 and the second metal film 50 is provided between the first substrate 20 and the second substrate 30.
The drive electrode is composed of a first electrode 21 formed on the first substrate 20 and a second electrode 31 formed on the second substrate 30 and facing the first electrode 21.
In the present embodiment, as described above, the variable gap filter 1 having a square shape in plan view is exemplified, but the present invention is not limited to this, and for example, it is formed in a circular shape in plan view and a polygonal shape in plan view. May be.

<Configuration of the first substrate>
As shown in FIGS. 1 and 2, the first substrate 20 is formed of a substantially square glass substrate having a thickness of, for example, 500 μm.
In the first substrate 20, a recess 25 is formed on the surface facing the second substrate 30, and the first electrode 21 and the first metal film 40 are provided in the recess 25.

A first metal film 40 as a first optical film formed in a circular shape with a diameter of about 3 mm, for example, is formed at the center of the first substrate 20.
The first metal film 40 is composed of a film made of Ag alone or an alloy containing Ag as a main component, and has a thickness of about 50 nm. In addition, the first metal film 40 may be composed of a film made of any one of Au alone, an alloy containing Au as a main component, Cu simple substance, and an alloy containing Cu as a main component. These materials can be formed as a metal film by a sputtering method and are effective as materials for optical films having both reflection and transmission characteristics.

A dielectric film 41 is formed so as to cover the side surface from above the first metal film 40.
FIG. 3 is an enlarged view showing a portion of the first metal film in the present embodiment, FIG. 3 (a) is a schematic plan view, and FIG. 3 (b) is a schematic cross section taken along the line BB in FIG. 3 (a). FIG.
The thickness of the dielectric film 42 covering the peripheral end portion along the outer shape in plan view of the first metal film 40 is formed to be thicker than the thickness of the dielectric film 43 covering the light incident portion that is a portion where incident light is incident. Has been. Specifically, the dielectric film 43 covering the light incident part has a thickness of about 20 nm, and the dielectric film 42 covering the peripheral edge part has a thickness of about 50 nm. That is, the protrusion of the dielectric film 41 is formed in an annular shape along the periphery of the first metal film 40.
The thickness (about 20 nm) of the dielectric film 43 covering the light incident portion is set to a thickness that does not impair the optical characteristics as the optical film. The light incident portion is an effective portion where light enters and exhibits the function of the filter, or a portion excluding the peripheral end portion of the first metal film 40.

  The material of the dielectric film 41 is formed of an Al oxide film or an Al nitride film. As other materials, in addition to Al oxide film or Al nitride film, Si oxide film, Si nitride film, Ti oxide film, Ti nitride film, Ta oxide film, Ta nitride film, Any film of the ITO film, Mg fluoride film group, or a laminated film thereof may be used. Since these materials have an effect of preventing contact between the first metal film 40 and a gas that causes oxidation or sulfurization, the first metal film has heat resistance and light transmission. 40 can function as a protective film for 40.

Next, as shown in FIGS. 1 and 2, a first electrode 21 as a drive electrode is formed in a ring shape so as to surround the first metal film 40 of the first substrate 20.
A lead electrode 27 is connected to the first electrode 21, and the lead electrode 27 is connected to a connection pad 23 provided at a corner of the first substrate 20.
In addition, a connection pad 24 is provided diagonally to the connection pad 23, and can be connected to a second electrode 31 formed on a second substrate 30 described later.

  A plasma polymerized film 38 as a bonding film made of polyorganosiloxane or the like as a main material is formed outside the first electrode 21, and its surface is activated by UV irradiation or the like to activate the first substrate 20 and the second substrate. 30 can be joined.

<Configuration of second substrate>
The second substrate 30 is formed, for example, by processing a glass substrate having a thickness dimension of 200 μm by etching.
As shown in FIGS. 1 and 2, the second substrate 30 has a circular movable portion 36 centered on the center of the substrate in a plan view, and a connection that is coaxial with the movable portion 36 and holds the movable portion 36. Holding part 35.

  The movable part 36 is formed to have a thickness dimension larger than that of the connection holding part 35. For example, in the present embodiment, the movable part 36 is formed to have a thickness of 200 μm, which is the same as the thickness dimension of the second substrate 30, as shown in FIG. .

A second metal film 50 as a second optical film facing the first metal film 40 is formed at the center of the second substrate 30 of the movable portion 36. The second metal film 50 has the same configuration as the first metal film 40 and is held in parallel with the first metal film 40 via a gap. In addition, since the structure of the 2nd metal film 50 is the same as the 1st metal film 40, description here is abbreviate | omitted.
A dielectric film 51 having a thickness of about 20 nm is formed so as to cover the side surface of the second metal film 50 from above. Since the material of the dielectric film 51 is the same as that of the dielectric film 41, description thereof is omitted.

The connection holding part 35 is a diaphragm surrounding the periphery of the movable part 36, and has a thickness dimension of, for example, 50 μm. A ring-shaped second electrode 31 facing the first electrode 21 with a gap of about 1 μm is formed on the surface of the connection holding portion 35 facing the first substrate 20. Here, the second electrode 31 and the first electrode 21 described above constitute an electrostatic actuator.
The second electrode 31 is connected to a lead electrode 37 formed toward the corner of the second substrate 30. In addition, a cutout portion 39 a that is cut out in a rectangular shape is formed at a corner portion of the second substrate 30 toward the extraction electrode 37. Further, a similar notch 39 b is formed at the diagonal of the notch 39 a of the second substrate 30.

  A plasma polymerized film 38 as a bonding film using polyorganosiloxane or the like as a main material is formed outside the second electrode 31, and the surface is activated by UV irradiation or the like to activate the first substrate 20 and the second substrate. 30 can be joined.

  Further, in the state where the first substrate 20 and the second substrate 30 are joined, an Ag paste or the like is used between the two substrates in order to connect the connection pads 24 of the first substrate 20 and the extraction electrodes 37 of the second substrate 30. The conductive member 28 is disposed, and the second electrode 31 and the connection pad 24 are electrically connected.

  In the variable gap filter 1 having such a configuration, by applying a voltage between the first electrode 21 and the second electrode 31, an attractive force acts between the two electrodes due to electrostatic action. At this time, since the connection holding part 35 is formed on the second substrate 30, the connection holding part 35 bends and the movable part 36 moves so that the gap between the first metal film 40 and the second metal film 50 is formed. Change. From this, it is possible to emit light in a desired wavelength band corresponding to the gap by controlling the gap size.

<Method of forming metal film and dielectric film>
Next, a method for forming the metal film and the dielectric film in the variable gap filter will be briefly described.
FIG. 4 is a process diagram for explaining the method of forming the first metal film and the dielectric film of the present embodiment.
First, as shown in FIG. 4A, the first metal film 40 is formed on the first substrate 20. The first metal film 40 is formed by a technique such as sputtering or vapor deposition using a metal mask 60a. Further, the first metal film 40 may be formed using a photolithography technique.
Subsequently, as shown in FIG. 4B, a dielectric film 41 covering the side surface from the surface of the first metal film 40 is formed. The dielectric film 41 is formed by a technique such as sputtering using a metal mask 60b. The dielectric film 41 is formed to a thickness of about 50 nm.
Next, as shown in FIG. 4C, a part of the dielectric film 41 is dry etched. In the dry etching of the dielectric film 41, a metal mask 60c having an opening smaller than the outer shape of the first metal film 40 is used, and a thickness of about 30 nm is etched through the opening so that a thickness of about 20 nm remains.

  As described above, the dielectric film 43 covering the light incident portion of the first metal film 40 is formed to a thickness of about 20 nm, and the dielectric film 42 covering the peripheral end portion of the first metal film 40 is about 50 nm thick. To form. That is, a ring-shaped protrusion having a height of about 30 nm is formed by the dielectric film 41 at the peripheral end portion of the first metal film 40.

  In the present embodiment, the ring-shaped protrusion is provided on the first substrate side which is the fixed substrate on the dielectric film covering the metal film, but the dielectric covering the second metal film on the second substrate side on the movable substrate side. A ring-shaped protrusion as described above may be provided on the film.

As described above, in the variable gap filter 1 as the optical filter of the present embodiment, the dielectric film 41 covers from the upper side to the side surface of the first metal film 40, and the first metal film 40 has the first end at the peripheral end portion. The dielectric film 41 is formed thicker than the light incident portion of the metal film 40.
As described above, since the first metal film 40 constituting the optical film is covered with the dielectric film from the upper side to the side of the first metal film 40, the first metal film 40 is deteriorated in characteristics such as oxidation and sulfurization. Can be prevented.

  Further, since the dielectric film 41 is formed thicker than the light incident part at the peripheral edge of the first metal film 40, charges are present above the first metal film 40 and the second metal film 50. When charged and attracted to each other, the dielectric film 41 formed to have a large thickness serves as a stopper, and the dielectric film 42 formed on the first metal film 40 and the second metal film 50 It is possible to prevent the dielectric film 51 formed on the substrate from sticking. As described above, the present embodiment realizes an optical filter in which the dielectric film 41 prevents the deterioration of the characteristics of the optical film and can appropriately maintain the gap dimension between the first metal film 40 and the second metal film 50.

  As described above, the present invention is suitable for application to the variable gap filter described in this embodiment. However, the present invention is not limited to this example, and the present invention is applicable to all structures (elements and devices) using a metal film having a minute gap between mirrors and having both light reflection characteristics and light transmission characteristics. Is possible.

(Modification)
Next, a modified example of the variable gap filter will be described. In this modification, only the configuration of the dielectric film formed on the first substrate is different from that of the first embodiment, and the portion will be described. In addition, about the same component as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 5 is a partially enlarged view showing a first metal film in a variable gap filter according to a modification of the first embodiment, FIG. 5A is a schematic plan view, and FIG. 5B is C in FIG. It is a schematic sectional drawing in alignment with -C disconnection.

A first metal film 40 is formed on the first substrate 20, and a dielectric film 41 a is formed so as to cover the side surface from above the first metal film 40. The thickness of the dielectric film 41a is set to about 20 nm.
A dielectric film 41b is formed on the dielectric film 41a. The dielectric film 41b is formed so as to surround the first metal film 40 along the peripheral end portion along the outer shape of the first metal film 40 in plan view and to face the semicircular rings. Since the metal film is used for formation, the dielectric film 41b has a shape in which one or more shadow portions appear by a tie bar holding the central mask portion, and the ring is cut. The thickness of the dielectric film 41b is set to about 30 nm.

  Thus, the dielectric film 41 b is formed as a protrusion along the periphery of the first metal film 40. As described above, the structure of the present modification has an advantage that the height of the protrusion can be easily set by appropriately setting the thickness of the dielectric film 41b.

<Method of forming metal film and dielectric film>
Next, a method for forming the metal film and the dielectric film in the variable gap filter will be briefly described.
FIG. 6 is a process diagram illustrating a method of forming the first metal film and the dielectric film according to this modification.
First, as shown in FIG. 6A, the first metal film 40 is formed on the first substrate 20. The first metal film 40 is formed by a technique such as sputtering or vapor deposition using a metal mask 60a. Further, the first metal film 40 may be formed using a photolithography technique.
Subsequently, as shown in FIG. 6B, a dielectric film 41a covering the side surface from the surface of the first metal film 40 is formed. The dielectric film 41a is formed by a technique such as sputtering using a metal mask 60b. The dielectric film 41a is formed to a thickness of about 20 nm.
Next, as shown in FIG. 6C, a dielectric film 41b is formed from above the dielectric film 41a. For the formation of the dielectric film 41b, a metal mask 60d covering the central portion of the dielectric film 41a is used. The dielectric film 41b is formed so as to surround the first metal film 40 along the peripheral end portion of the outer shape in plan view of the first metal film 40, and is formed by a technique such as sputtering. The dielectric film 41b is formed to a thickness of about 30 nm.

  Thus, in this modification, the dielectric film is composed of two layers, but the same effect as in the first embodiment can also be obtained with this structure.

  Next, another modification will be described. In the first embodiment and the modification described above, the optical film is formed of a single layer of metal film, but may be an optical film in which a metal film is formed on a dielectric film. This structure has an effect of improving the reflectance of light by providing a dielectric film under the metal film. In addition, about the same component as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIGS. 7A and 7B are schematic cross-sectional views showing the configuration of an optical film in another modification.
In FIG. 7A, a dielectric film 44 is formed in the central portion of the first substrate 20, and a first metal film 40 is formed thereon, and these two layers function as an optical film.
A dielectric film 41 is formed so as to cover the side surface of the first metal film 40 from above and the side surface of the dielectric film 44. As in the first embodiment, the dielectric film 41 has a thickness at the peripheral end portion along the outer shape of the first metal film 40 in the dielectric film 41 in a plan view. It is formed thicker than the thickness of the part. That is, the protrusion of the dielectric film is formed in an annular shape along the periphery of the first metal film 40.

In FIG. 7B, a dielectric film 44 is formed at the center of the first substrate 20, and a first metal film 40 is formed thereon, and these two layers function as an optical film.
A dielectric film 41 a is formed so as to cover the side surface of the first metal film 40 from above and the side surface of the dielectric film 44. Further, a dielectric film 41b is formed on the dielectric film 41a. The dielectric film 41b is formed so as to surround the first metal film 40 along the peripheral end portion along the outer shape of the first metal film 40 in plan view.

(Second Embodiment)
FIG. 8A and FIG. 8B are diagrams showing an example of the configuration of an optical filter module using a variable gap filter. As shown in FIG. 8A, the variable gap filter includes a first substrate (for example, a fixed substrate) 20, a second substrate (for example, a movable substrate) 30, and a main substrate 20. The first metal film 40 provided on the surface (front surface), the second metal film 50 provided on the main surface (front surface) of the second substrate 30, and an actuator for adjusting the gap (distance) between the substrates (for example, 80a, 80b).

  Note that at least one of the first substrate 20 and the second substrate 30 may be a movable substrate, and both may be movable substrates. The actuator 80a and the actuator 80b are driven by a drive unit (drive circuit) 301a and a drive unit (drive circuit) 301b. The operations of the drive units (drive circuits) 301 a and 301 b are controlled by a control unit (control circuit) 303.

  Light Lin incident from the outside at a predetermined angle θ passes through the first metal film 40 with almost no scattering. The reflection of light is repeated between the first metal film 40 provided on the first substrate 20 and the second metal film 50 provided on the second substrate 30. As a result, interference of light occurs, and only light having a wavelength satisfying a specific condition is intensified, and a part of the light having the enhanced wavelength passes through the second metal film 50 on the second substrate 30, It reaches the light receiving part (light receiving element) 400. Which wavelength of light is intensified by interference depends on the gap G 1 between the first substrate 20 and the second substrate 30. Therefore, the wavelength band of light passing therethrough can be changed by variably controlling the gap G1.

  When this optical filter module is used, a spectrometer as shown in FIG. 8B can be configured. Examples of the spectrophotometer include a colorimeter, a spectroscopic analyzer, a spectroscopic spectrum analyzer, and the like.

  In the spectrophotometer shown in FIG. 8B, for example, the light source 100 is used when performing colorimetry of the sample 200, and the light source 100 ′ is used when performing spectroscopic analysis of the sample 200. .

  The spectrophotometer includes a light source 100 (or 100 ′), an optical filter (spectral section) 300 including a plurality of wavelength variable bandpass filters (variable BPF (1) to variable BPF (4)), and light reception such as a photodiode. A light receiving unit 400 including the elements PD (1) to PD (4), and a signal processing for obtaining a spectrophotometric distribution and the like by executing a given signal processing based on a light receiving signal (light amount data) obtained from the light receiving unit 400 Unit 600, drive unit 301 that drives each of variable BPF (1) to variable BPF (4), and control unit 303 that variably controls each spectral band of variable BPF (1) to variable BPF (4) Have. The signal processing unit 600 includes a signal processing circuit 501, and a correction operation unit 500 can be provided as necessary. By measuring the spectrophotometric distribution, for example, color measurement of the sample 200, component analysis of the sample 200, and the like can be performed. Further, as the light source 100 (100 '), for example, a light source (solid light emitting element light source) using a solid light emitting element such as an incandescent bulb, a fluorescent lamp, a discharge tube, or an LED can be used.

  The optical filter module 350 is configured by the optical filter 300 and the light receiving unit 400. The optical filter module 350 can be applied to a spectrometer, and can also be used as, for example, a receiving unit (including a light receiving optical system and a light receiving element) of an optical communication device. The optical filter module 350 according to the present embodiment has an advantage that reliability is high because deterioration of characteristics of the optical film is suppressed and adhesion between the first metal film 40 and the second metal film 50 can be prevented.

(Third embodiment)
Next, as an example of a spectrometer, a food analyzer that analyzes substance components will be described.

FIG. 9 is a diagram illustrating a schematic configuration of a food analyzer that is an example of an optical analyzer using a variable gap filter.
As shown in FIG. 9, the food analysis apparatus 700 includes a detector 710 (optical module), a control unit 720, and a display unit 730. The detector 710 includes a light source 711 that emits light, an imaging lens 712 into which light from the measurement target is introduced, a variable gap filter 715 that splits the light introduced from the imaging lens 712, and the dispersed light. An imaging unit 713 (light receiving unit) for detection.
In addition, the control unit 720 controls the light source control unit 721 that controls the turning on / off of the light source 711 and the brightness control at the time of lighting, the voltage control unit 722 that controls the variable gap filter 715, and the imaging unit 713, A detection control unit 723 that acquires a spectral image captured by the imaging unit 713, a signal processing unit 724, and a storage unit 725 are provided.

  In the food analyzer 700, when the system is driven, the light source 711 is controlled by the light source control unit 721, and the measurement object is irradiated with light from the light source 711. Then, the light reflected by the measurement object enters the variable gap filter 715 through the imaging lens 712. The variable gap filter 715 is applied with a voltage capable of spectrally dividing a desired wavelength under the control of the voltage control unit 722, and the dispersed light is imaged by an imaging unit 713 configured by, for example, a CCD camera or the like. The captured light is accumulated in the storage unit 725 as a spectral image. In addition, the signal processing unit 724 controls the voltage control unit 722 to change the voltage value applied to the variable gap filter 715, and acquires a spectral image for each wavelength.

Then, the signal processing unit 724 performs arithmetic processing on the data of each pixel in each image accumulated in the storage unit 725 to obtain a spectrum at each pixel. In addition, the storage unit 725 stores, for example, information related to food components with respect to the spectrum, and the signal processing unit 724 analyzes the obtained spectrum data based on the information related to food stored in the storage unit 725. Determine the food components contained in the test object and their contents. Moreover, a food calorie, a freshness, etc. are computable from the obtained food component and content. Furthermore, by analyzing the spectral distribution in the image, it is possible to extract a portion of the food to be inspected that has reduced freshness, and to detect foreign substances contained in the food. Can also be implemented.
Then, the signal processing unit 724 performs processing for causing the display unit 730 to display information such as the components and contents of the food to be inspected and the calories and freshness obtained as described above.

FIG. 9 shows an example of the food analysis device 700, which can be used as a biological analysis device for analyzing biological components such as measurement and analysis of body fluid components such as blood, etc., by a substantially similar configuration. It can also be used as an electronic endoscope system equipped with such a biological analyzer.
Furthermore, it can also be used as a mineral analyzer for performing component analysis of minerals.

(Fourth embodiment)
Next, a gas detection device that detects a substance in a gas will be described as an example of a spectroscopic measurement device. In this gas detection device, a variable gap filter is used as a spectroscope.
FIG. 10 is a configuration diagram illustrating an example of the configuration of the gas detection device. The gas detection device 900 has consumables that are replaced every time the sensor chip 910, the suction channel 930, and the like are detected in the main body.

  The main structure of the main body is composed of a sensor cover 911 that can be opened and closed so that consumables can be stored and replaced, a discharge means 913, a main body housing 905, a light source 915, lenses 916, 917, 919, a filter 920, a spectrometer ( A variable gap filter) 921, a light receiving element 922, and the like; a signal processing / control unit 923 that processes the detected signal and controls the detection unit; a power supply unit 924 that supplies power; and an external interface A connection portion 925, a connection portion 926, and the like.

  When the discharge means 913 is operated, the suction flow path 930, the flow path in the sensor chip 910, and the discharge flow path 931 become negative pressure, and a gas sample containing a substance to be detected (target substance) to be detected from the suction port 912 Is sucked. A dust removal filter 940 is provided at the entrance of the suction flow path 930 to remove relatively large dust, some water vapor, and the like. The gas sample passes through the suction channel 930 and is discharged from the discharge channel 931 via the channel in the sensor chip 910. At that time, the target substance passes near the surface of the sensor chip 910 and is adsorbed or scattered by the sensor chip 910 so that it can be detected.

  The sensor chip 910 is irradiated with light from a light source (laser light source) 915 having a single wavelength and linearly polarized light, and SERS (surface enhanced Raman scattering) light is emitted from the sensor chip 910 and condensed by a lens 917. Then, the light enters the light receiving element 922 by the half mirror 918. Since this light includes Rayleigh scattered light and SERS light having the same wavelength as the incident light from the light source, the Rayleigh scattered light is removed by the filter 920 and enters the spectroscope (optical filter) 921. . The spectroscope 921 and the light receiving element 922 obtain a fingerprint spectrum peculiar to the target substance, and can be identified as the target substance by collating it with data stored in advance.

Next, the configuration and operation of the control system of the gas detection device 900 will be described with reference to a block diagram.
FIG. 11 is a block diagram illustrating a configuration of a control system according to the gas detection device. Reference is also made to FIG. An operation panel 960, a display unit 961, a connection unit 925 for interface with the outside, and a power supply unit 924 are provided on the surface of the gas detection device 900. When the power supply unit 924 is a secondary battery, a connection unit 926 for charging is provided. Inside the sensor unit cover 911 at the top of the main body is a sensor chip 910 and a sensor chip detector 950 for detecting the presence or absence of the sensor chip 910 and reading the code of the sensor chip 910. Then, the information is sent to a CPU (Central Processing Unit) constituting the signal processing / control unit 923 for determination. Since this state is a state where preparation for detection is completed, a display signal indicating that the preparation is OK is output from the CPU to the display unit 961. The operator who sees it outputs an instruction signal from the operation panel 960 to the CPU to start detection.

  When the CPU receives a detection start signal, it first issues a light source activation signal to the light source driver circuit 941 to activate the light source 915. The light source 915 incorporates a temperature sensor and a light amount sensor, and the information is sent to the CPU to determine whether it is stable. If the determination is OK, next, a signal for operating the discharge means 913 is directed from the CPU to the discharge means driver circuit 946 to guide the gas sample containing the target substance to be detected to the vicinity of the surface of the sensor chip 910. The gas sample is discharged from the suction port 912 to the outside through the suction flow path 930, the sensor chip space, and the discharge flow path 931.

  The detection system operates by a light source 915 (laser light source) that emits a linearly polarized light having a single wavelength, and is driven by a light source driver circuit 941 in response to a signal from the CPU to emit laser light. This laser light is applied to the sensor chip 910, and Rayleigh scattered light and SERS (surface enhanced Raman scattered) light enter the light receiving side via the lenses 916, 917 and the half mirror 918.

  First, only SERS light enters the spectroscope 921 through a filter 920 for blocking Rayleigh scattered light. The spectroscope 921 is controlled by a spectroscope driver circuit 942. In this case, the band of transmitted light (λs to λe) and the half-value width are set, and the wavelength that is sequentially transmitted through the half-value width is started from λs, and the half-value width of the half-value width is repeated by λe. The intensity of the optical signal is converted into an electric signal by the light receiving circuit 943. By doing so, the spectrum of the detected SERS light is obtained.

  The SERS light spectrum of the target substance thus obtained is compared with the spectrum data stored in the ROM of the signal processing / control unit 923 to determine whether or not the target substance is used, thereby specifying the substance. In order to notify the operator of the determination result, the result information is displayed on the display unit 961 from the CPU. When the obtained substance identification result is transmitted as information to the outside, it is sent from the connection unit 925 based on a predetermined interface standard.

  In such a gas detection apparatus 900, metal nanoparticles having a size of nanometer order are arranged on the sensor chip 910 in the direction of a minute gap, and the metal nanoparticles are irradiated with laser light. As a result, the excited localized surface plasmon resonance occurs more efficiently. As a result, surface enhanced Raman scattering is performed, and a gas detection device capable of detecting a substance with high sensitivity can be realized.

According to the gas detection apparatus 900 described above, it is possible to detect various substances to be detected. Examples of substances to be detected are shown below.
In the security field, it is possible to detect narcotics and explosives, and detect flammable dangerous goods at airports, ports, and transportation facilities.

In the medical / health field, detection of various viruses causing infectious diseases such as influenza, detection of hydrogen sulfide, methyl mercaptan and dimethyl sulfide in oral gas to determine periodontal disease, Asthma is tested by detecting contained nitric oxide (NO). Alternatively, by detecting volatile organic compounds (VOC) contained in exhaled gas, screening screening for cancer, by detecting acetone contained in exhaled gas, fat burning monitor, by detecting isoprene contained in exhaled breath A cholesterol monitor or the like is possible.
It is also possible to inspect benzene, toluene, xylene, ethylbenzene, styrene, formaldehyde, and the like, which are volatile organic compounds (VOC) contained in indoor air.

  In addition, as a spectroscopic measuring device, it can utilize for the spectroscopic camera etc. which image a spectroscopic image by disperse | distributing light using an optical filter. For example, an infrared camera with a built-in optical filter may be used as a spectroscopic camera.

(Fifth embodiment)
FIG. 12 is a block diagram illustrating a schematic configuration of a transmitter of a wavelength division multiplexing communication system that is an example of an optical device. In wavelength division multiplexing (WDM) communication, if multiple signals with different wavelengths are used in a single optical fiber by using the characteristic that signals with different wavelengths do not interfere with each other, The amount of data transmission can be improved without increasing the number of lines.

  12, the wavelength division multiplexing transmitter 800 has an optical filter 300 on which light from the light source 100 is incident, and the light of the plurality of wavelengths λ0, λ1, λ2,. Transmitters 311, 312, and 313 are provided for each wavelength. The optical pulse signals for a plurality of channels from the transmitters 311, 312, and 313 are combined into one by the wavelength multiplexing device 321 and transmitted to one optical fiber transmission line 331.

  The present invention can be similarly applied to an optical code division multiplexing (OCDM) transmitter. This is because OCDM identifies channels by pattern matching of encoded optical pulse signals, but the optical pulses constituting the optical pulse signals include optical components having different wavelengths. As described above, by applying the present invention to an optical device, a highly reliable optical device (for example, an optical communication application device) in which the deterioration of the characteristics of the optical film is suppressed is realized.

  DESCRIPTION OF SYMBOLS 1 ... Variable gap filter, 20 ... 1st board | substrate, 21 ... 1st electrode, 23, 24 ... Connection pad, 25 ... Recessed part, 27 ... Extraction electrode, 28 ... Conductive member, 30 ... 2nd board | substrate, 31 ... 2nd Electrode 35 ... Connection holding part 36 ... Movable part 37 ... Lead electrode 38 ... Plasma polymerized film 39a, 39b ... Notch part 40 ... First metal film as first optical film 41 ... Dielectric film 41a, 41b ... dielectric film, 42 ... dielectric film formed on the peripheral edge of the metal film, 43 ... dielectric film formed on the light incident part of the metal film, 50 ... second as the second optical film 2 metal films, 51 ... dielectric films, 60a, 60b, 60c, 60d ... metal masks, 350 ... optical filter modules, 700 ... food analyzers, 800 ... wavelength multiplex transmitters, 900 ... gas detectors.

Claims (6)

A first optical film having reflection and transmission characteristics;
A second optical film disposed opposite to the first optical film via a gap and having reflection characteristics and transmission characteristics;
A first electrode formed around the first optical film;
A second electrode formed around the second optical film and disposed opposite to the first electrode;
Including
At least one of the first optical film and the second optical film has a metal film, and the surface and side surfaces of the metal film are covered with a dielectric film,
The optical filter, wherein the dielectric film is formed thicker at a peripheral end portion of the metal film than a light incident part where light enters the metal film. The optical filter according to claim 1,
The material of the metal film is any one of Ag alone, an alloy containing Ag as a main component, Au alone, an alloy containing Au as a main component, Cu simple substance, and an alloy containing Cu as a main component. filter. The optical filter according to claim 1,
The dielectric film is made of Al oxide film, Al nitride film, Si oxide film, Si nitride film, Ti oxide film, Ti nitride film, Ta oxide film, Ta nitride film, ITO film An optical filter comprising any one film of the first group of Mg fluoride films, or a laminated film of any one oxide film and one nitride film of the first group. An optical filter according to any one of claims 1 to 3,
A light receiving element that receives light transmitted through the optical filter;
An optical filter module comprising: An optical filter according to any one of claims 1 to 3,
A light receiving element that receives light transmitted through the optical filter;
And a signal processing unit that performs given signal processing based on signal processing based on a signal obtained from the light receiving element.   An optical device comprising the optical filter according to any one of claims 1 to 3.

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