JP2012154780A - Spectroscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized spectroscope requiring only spatially small volume, integrally formed, capable of resisting vibration and eliminating the necessity of large voltage, and allowed to be carried.SOLUTION: A linear sensor 1 is an infrared sensor having such a configuration that a plurality of pixels sensitive to infrared rays are linearly arrayed at a predetermined pitch. A Fabry-Perot interferometer 2 has such a configuration that respective ends of two mirrors are fixed so that the two mirrors oppositely separated and has such a characteristic that a resonance wavelength is changed in a direction parallel with the array direction of the pixels configuring the linear sensor 1. A light parallelization device 3 has such a configuration that many holes having the same diameter as a pixel pitch of the plurality of pixels configuring the linear sensor 1 are pierced in a sheet capable of absorbing near infrared light and having a predetermined thickness. An optical filter 4 prevents incidence of light of excess wavelengths on the Fabry-Perot interferometer 2. A spectroscope 10 can noninvasively obtain various information by transmitting light from a light source 6 to a measuring object 7 such as a human finger.

Description

  The present invention relates to a spectroscope, and more particularly to a spectroscope that acquires spectral characteristics of an object to be measured.

  By obtaining spectral characteristics of light that is transmitted through or reflected by a substance or emitted from a substance, it is possible to know various properties related to the substance. The spectroscope obtains the spectral characteristics. However, spectrometers often require a large volume of space in the optical system. In particular, when a diffraction grating is used, a large volume space for spreading the decomposed light of each wavelength is required, so that the apparatus becomes large. On the other hand, when a Fabry-Perot resonator (Fabry-Perot etalon) is used, the required space is relatively small compared to the case where a diffraction grating is used, which is advantageous for downsizing.

  Patent Document 1 describes a spectrometer that combines a Fabry-Perot interferometer, a lens, and a linear sensor. In the spectroscope described in Patent Document 1, the light collecting position is different for each wavelength. Therefore, the light intensity is read by a linear sensor arranged on the straight line of the light collecting position, and a predetermined value is obtained from the position of each pixel and the signal intensity. An arithmetic operation is performed to obtain a wavelength distribution.

  Patent Document 2 describes a variable interferometer that obtains a wavelength distribution by varying the interval between Fabry-Perot interferometers by electrostatic attraction. Although not shown in Patent Document 2, a spectroscope can be configured by providing the variable interferor with a component for controlling the incident direction of light.

Japanese Patent No. 2629844 Japanese Examined Patent Publication No. 4-046369

  However, the spectroscope described in Patent Document 1 requires a lens having the size of a Fabry-Perot interferometer, and requires a relatively large volume space for condensing light. There is no problem. In addition, in the spectroscope configured using the variable interferometer described in Patent Document 2, a large voltage is required to generate electrostatic attraction, and the distance is changed while maintaining the parallelism of the entire Fabry-Perot interferometer. There is a problem that it is difficult. Furthermore, the spectroscope using the spectroscope described in Patent Document 1 and the variable interferometer described in Patent Document 2 is composed of a plurality of optical components having a certain amount of clearance from each other, so that it is relatively vulnerable to vibration. There is also.

  The present invention has been made in view of the above points, and it is an object of the present invention to provide a small-sized spectroscope that can be carried around without requiring a small volume, being integrated, strong against vibration, requiring no large voltage. And

  In order to achieve the above object, a spectroscope according to a first invention includes a linear sensor in which a plurality of pixels having sensitivity in a predetermined wavelength range are linearly arranged at a predetermined pitch, and a plurality of pixels constituting the linear sensor. A Fabry-Perot interferometer that splits the incident light and enters the linear sensor, and a light beam that collimates the incident light to the Fabry-Perot interferometer. It is characterized by comprising a collimating means and a light source for entering the light to be detected having a wavelength to be measured into the light collimating means.

  In order to achieve the above object, the spectroscope according to the second aspect of the present invention further includes an optical filter for removing unnecessary wavelengths of light incident on the linear sensor between the linear sensor and the measurement object. It is characterized by.

  In order to achieve the above object, a spectroscope according to a third aspect of the present invention is a Fabry-Perot interferometer, in which both ends of flat plate-like first and second dielectrics whose reflecting surfaces formed on one surface face each other are spaced apart from each other. Is fixed, and the first and second dielectrics are arranged so that the distance between them is linearly changed from the distance between one fixed end to the distance between the other fixed ends. It is the structure which forms distribution of this.

  In order to achieve the above object, a spectroscope according to a fourth aspect of the present invention is that the beam collimating means comprises a sheet having a plurality of holes, each of the plurality of holes having an axial length. The length is greater than the maximum length of the cross section perpendicular to the direction, and the inner side surface is in a non-reflective state.

  In order to achieve the above object, a spectroscope according to a fifth aspect of the present invention is that the linear sensor includes a Schottky barrier diode having a structure in which a plurality of pixels are in contact with metal on the surface of the substrate. The light is incident from the back surface of the substrate through a Fabry-Perot interferometer.

  In order to achieve the above object, a spectroscope according to a sixth aspect of the invention includes a transfer means for transferring the charge accumulated in the Schottky barrier diode to a high concentration diffusion layer having a conductivity type opposite to that of the substrate, and a high concentration diffusion. Readout circuit means for reading out the potential change accumulated in the layer as a signal is provided.

  Furthermore, in order to achieve the above object, the spectroscope of the seventh invention is a light source for emitting light whose peak wavelength is known in advance, and diffusing the light from the light source to the light collimating means. Identify the incident diffuser and the pixel whose readout signal has the maximum intensity among the plurality of pixels as the pixel whose peak wavelength is being measured, and the difference in the known measurement wavelength between the identified pixel and the adjacent pixel And a specifying means for specifying the measurement wavelength for all of the plurality of pixels.

  According to the present invention, a small space is sufficient, it is integrated, strong against vibration, does not require a large voltage, and can be carried.

It is a block diagram of one embodiment of the spectrometer of the present invention. It is a block diagram of an example of the Fabry-Perot interferometer in FIG. It is a characteristic view which shows the resolution and reflectance of a Fabry-Perot resonator. It is a block diagram of each other example of a Fabry-Perot interferometer. It is explanatory drawing of the angle of the incident light of a Fabry-Perot interferometer. It is a figure explaining an example of the light parallelization method. It is a perspective view of an example of the beam collimating device in FIG. It is a block diagram of an example in the chip | tip containing a linear sensor. It is the structure sectional drawing and circuit diagram of an example of 1 pixel of a linear sensor, and a read-out circuit. 10 is a timing chart for explaining the operation of FIG. 9. It is a block diagram which shows an example of the correction method of the principal part of one Embodiment of the spectrometer of this invention.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration diagram of an embodiment of a spectrometer according to the present invention. As shown in the figure, the spectroscope 10 of the present embodiment includes a linear sensor 1 sensitive to infrared rays, a Fabry-Perot interferometer 2, a light collimating device 3 that collimates light, and an optical that transmits a specific wavelength. An object to be measured (here, an object to be measured (here, the filter 4) is provided between the spectroscope body 5 and the light source 6, which is composed of an integrated spectroscope body 5 in which the filters 4 are in close contact with each other or in contact with each other with almost no gap. 7) Spectral characteristics are measured. Here, it is assumed that the spectroscope 10 transmits light emitted from the light source 6 to a finger, which is the measurement object 7, and obtains infrared spectral characteristics having a wavelength of 1 μm to 2 μm.

  The linear sensor 1 is an infrared sensor having a configuration in which a plurality of pixels sensitive to infrared rays are arranged linearly at a predetermined pitch. As this linear sensor 1, for example, a thermal sensor that absorbs infrared rays and converts it into heat, a resistance bolometer type sensor that reads a change in temperature by a change in resistance, and a thermopile type sensor that reads the voltage of a thermocouple connected in series In addition, a sensor using a pyroelectric element or a quantum sensor that directly extracts light by photoelectric conversion can be used. Quantum sensors include InGaAs compound semiconductor photodiode arrays, or Schottky barrier diodes formed on the silicon substrate and using photoelectric conversion that occurs at the interface between the silicon substrate and the metal thin film.・ A diode type sensor can be considered. Here, a Schottky barrier diode type sensor is used as an example.

  The Fabry-Perot interferometer 2 is fixed at both ends so that the two mirrors are spaced apart from each other. For example, the distance between one of the fixed ends is 0.25 μm and the distance between the other fixed ends is 0.5. The structure is 5 μm and linearly changes between the two fixed ends. The interval 0.25 μm and 0.5 μm between the two fixed ends corresponds to a quarter length of 1 μm which is the shortest wavelength and 2 μm which is the longest wavelength, respectively. The distance between these two fixed ends can be changed according to the wavelength to be measured. The Fabry-Perot interferometer 2 has a characteristic that the resonance wavelength changes in a direction parallel to the arrangement direction of a plurality of pixels constituting the linear sensor 1, and splits incident light and enters the linear sensor 1. .

  The light collimating device 3 is intended to make light incident on the Fabry-Perot interferometer 2 vertically within a range of angles. The beam collimating device 3 has a structure in which a large number of holes of a specific size are opened and blocks light other than a certain angle, or a structure in which a large number of optical fibers are arranged. Therefore, it has a thickness of several millimeters at most, and can be bonded to the Fabry-Perot interferometer 2 and does not take up a spatial volume.

  The optical filter 4 is for preventing light having an extra wavelength from entering the Fabry-Perot interferometer 2. For example, when light of 1 μm or less enters the Fabry-Perot interferometer 2, there is a possibility of interference and detection. Provided. As will be described later, when a sensor is formed on a silicon substrate with a Schottky barrier diode, the silicon substrate itself performs an optical filter function, so that the optical filter 4 can be omitted.

  The Fabry-Perot interferometer 2, the beam collimating device 3, and the optical filter 4 do not have to be arranged in the order shown in FIG. For example, the beam collimating device 3 can be disposed on the Fabry-Perot interferometer 2 (that is, the light having an extra wavelength may be removed after the interference). Moreover, there is no difference in the light detected as a result regardless of the position of the optical filter 4. About arrangement | positioning, what is necessary is just to make it optimal arrangement | positioning suitably by design. That is, the Fabry-Perot interferometer 2, the beam collimating device 3, and the optical filter 4 may be arranged in any order. The optical filter 4 can be formed as a multilayer film on the surface of the Fabry-Perot interferometer 2, the beam collimating device 3, or the linear sensor 1, and can be integrated with each other.

  The light source 6 may be any light source that emits light having a wavelength to be measured. For example, a halogen lamp is suitable as a light source because it emits light in the near infrared region relatively uniformly and is easily obtained. In addition, one or a plurality of light emitting diodes (LEDs) may be used, or a phosphor using LED as a primary light source may be used. Further, directional light such as a laser may be incident on the measurement object 7 and the diffused light may be measured. Further, the position of the light source 6 is opposite to the linear sensor 1 in the embodiment of FIG. 1, but the light is reflected to the object 7 to be measured from the same direction as the linear sensor 1 or an optical fiber or the like. May be used to closely contact the measurement object 7 to detect the diffused light.

  Here, the measurement object 7 is a living human finger as a biological sample. The spectroscope 10 can obtain various information non-invasively (not affecting the living body) by transmitting light from the light source 6 to a human finger. For example, there is a glucose absorption band in the vicinity of a wavelength of 1.5 to 1.6 μm, and it is known that a blood glucose level can be measured by obtaining spectral characteristics including this region (for example, JP 2000-131322 A). See the official gazette).

  In addition, although the spectrometer 10 of this Embodiment has such an application in mind, it is not restricted to a biological body as the to-be-measured object 7, It measures the chemical characteristic of another inorganic substance and organic substance. Of course, this may be the purpose.

  Next, how the light is dispersed and detected in the spectroscope 10 having such a configuration will be described. First, the Fabry-Perot interferometer 2, which is an optical component performing spectroscopy, will be described with reference to FIG.

  First, it is assumed that the Fabry-Perot interferometer 2 has the following characteristics. It is assumed that the measurement wavelength is 1 to 2 μm and the wavelength resolution is 10 nm. If the pixels of the linear sensor 1 are prepared for this wavelength resolution, the number of pixels of the linear sensor 1 is 100. When the pixel pitch of the linear sensor 1 is 30 μm, the entire length of the linear sensor 1 is 3000 μm (= 3 mm).

  The structure of the Fabry-Perot interferometer 2 is as follows. In the Fabry-Perot interferometer 2, for example, flat dielectrics (for example, quartz) 20a and 20b that are transparent in the near-infrared region are opposed to each other, and one surface 23a, 23b of the dielectrics 20a and 20b is opposed to, for example, gold. Is formed by vapor deposition as a reflecting surface. The light emitting surfaces and the incident surfaces of the dielectrics 20a and 20b are provided with multilayer films 22a and 22b with antireflection coating, respectively.

  One end of each of the dielectrics 20a and 20b is fixed by a spacer 21a having a length of 0.25 μm, and the other end is fixed by a spacer 21b having a length of 0.5 μm. The above numerical values of 0.25 μm and 0.5 μm are 1/4 of the measurement wavelength of 1 to 2 μm. Further, the interval between the dielectrics 20a and 20b changes linearly from the interval between the one fixed ends (the length of the spacer 21a) to the interval between the other fixed ends (the length of the spacer 21b). The dielectric 20a having the reflective surface 23a constitutes a first mirror, and the dielectric 20b having the reflective surface 23b constitutes a second mirror. The Fabry-Perot interferometer 2 forms a distribution of resonance wavelengths by changing the interval between these two mirrors in a direction parallel to the arrangement direction of the plurality of pixels of the linear sensor 1.

  The reflectivity of the reflective surfaces 23a and 23b is 98.5% or more depending on the resolution. FIG. 3 shows the relationship between resolution and reflectance.

  Now, since the gap of the reflecting surface differs depending on the wavelength, as shown in FIG. 2, the reflecting surfaces 23a and 23b are not completely parallel, and there is a change in thickness of 0.25 μm between both ends. is there. However, since the horizontal length of the dielectrics 20a and 20b is 3000 μm with respect to the change in thickness of 0.25 μm, the inclination is about 0.3 seconds, and the parallelism is 1 second or less. For example, if the light 26 is incident perpendicularly to the reflecting surface 23b when the gap is 0.5 μm, the positional deviation is 0.08 μm even if it is reflected twice. Therefore, it can be seen that the Fabry-Perot interferometer 2 of FIG. 2 is sufficiently small with respect to light having a wavelength of 2 μm and causes self-interference, and thus acts as a Fabry-Perot resonator.

  The Fabry-Perot interferometer 2 does not have to have an air gap configuration as shown in FIG. For example, as shown in FIG. 4A, the shape of the gap may be made of a dielectric 24. The dielectric 24 has a trapezoidal processing type structure in which the thickness continuously changes from one end having a thickness of 0.25 μm to the other end having a thickness of 0.5 μm. The thickness of the dielectric 24 is shown as 0.25 μm and 0.5 μm as the dielectric constant 1 in FIG. 4A, but it should be understood that the thickness varies depending on the dielectric constant.

  Further, as shown in FIG. 4B, a dielectric constant modulation type dielectric 25 that gradually changes the dielectric constant inside the dielectric 25 forming parallel mirror surfaces in a predetermined direction. You can make it. Of course, both the dielectrics 24 and 25 are provided with a non-reflective coating on the light incident surface and light exit surface.

  Next, the angle of incident light of the Fabry-Perot interferometer 2 will be described.

  Since the pixel resolution is 10 nm, a certain pixel α in the linear sensor 1 and an adjacent pixel β are considered as shown in FIG. Since the wavelength to be detected is different by 10 nm between the pixel α and the pixel β, when the angle θ is tilted by about 6 degrees with respect to the vertical direction, the optical path length becomes 2.5 μm, which is a quarter wavelength of 10 nm. The light to be detected by the pixel β is detected by the pixel α. Therefore, some light collimating means is required before the light is incident on the Fabry-Perot interferometer 2. A method of collimating a lens can be used as a method of creating parallel rays. However, the lens collimation method requires a large volume of space, and the optical system requires a sturdy housing that does not cause misalignment, which further increases the shape of the spectrometer.

  Therefore, as a more desirable method, there is a method of shielding light other than a certain angle. As shown in FIG. 6, this method has a diameter of 30 μm which is the same as the pixel pitch of the linear sensor 1 and a depth of 350 μm which is larger than the diameter, and the inner side surface is made of a material which does not reflect light. This is a method using the perforated holes 31. According to this method, since the light passing through the hole 31 is limited to about 5 degrees, parallel light can be easily produced. Therefore, in the present embodiment, as the beam collimating device 3, as shown in the external perspective view of FIG. 7, a sheet 32 having a thickness of 350 μm that absorbs near infrared light (for example, an organic material such as plastic containing black paint) ) Having a large number of holes 31 having a diameter of 30 μm formed by a mold or the like.

  6 and 7, the beam collimating device 3 has a circular cross section in a direction perpendicular to the axial direction of the hole 31, but the shape is not limited to this. It may be a quadrangle, a polygon or any other shape. However, the hole of the beam collimating device 3 has the maximum length of the cross section perpendicular to the axial direction (diameter in the case of a circle, diagonal line in the case of a quadrangle, and length that crosses the cross section in the case of other shapes). The length in the axial direction (that is, the depth) is larger than the length (the length at which the length is increased), and the inner side surface must be in a non-reflective state.

  As another beam collimation method, there is a method in which a large number of optical fibers are bundled and processed into a sheet shape to allow light to pass therethrough. Since the optical fiber propagates by totally reflecting light at a certain angle or less, here, if a fiber having a total reflection angle of 6 degrees or less is used, only light at a certain angle can be extracted due to the properties of the optical fiber. The thickness of the optical fiber sheet may be several mm.

  Next, the linear sensor 1 will be described in detail. As described above, the linear sensor 1 includes a thermal type and a quantum type. Here, an example in which a Schottky barrier diode using a silicon substrate is used is shown in FIG.

  In FIG. 8, a chip 33 is a small chip having a length of 1 mm and a width of 4 mm. In this chip 33, a linear sensor 1 for detecting infrared rays, a readout circuit 34, an A / D conversion circuit 35, a control circuit 36, a power supply circuit 37, an input / output (I / O) circuit 38, and a pad 39 is provided.

  The linear sensor 1 has a configuration in which a plurality of pixels sensitive to infrared rays are arranged in a straight line, for example, at a pitch of 30 μm. The vertical length of each pixel of the linear sensor 1 is 100 μm. A readout circuit 34 is connected to each pixel, and the readout circuit 34 sequentially reads out the signal of each pixel and supplies it to the A / D conversion circuit 35 to convert it into a digital signal. The control circuit 36 controls operations of the reading circuit 34 and the A / D conversion circuit 35. The power supply circuit 37 converts the power supply voltage supplied from the outside into an appropriate voltage and supplies it to the read circuit 34, the A / D conversion circuit 35, and the control circuit 36, respectively. The I / O circuit 38 exchanges signals with the outside of the chip 33 and communicates with the A / D conversion circuit 35, the control circuit 36, and the power supply circuit 37. The pad 39 is an area having wiring with the outside.

Next, one pixel of the linear sensor 1 and how to read the signal will be described in detail. FIG. 9 shows a structural cross-sectional view and a circuit diagram of an example of one pixel of the linear sensor 1 and a readout circuit. In the figure, a P-type silicon substrate 40 is provided with a contact P ⁺ diffusion layer 41, a metal thin film 42, an N-type diffusion layer 43, and N ⁺ diffusion layers 46 and 47, respectively. A transfer gate electrode 44 and a reset gate electrode 45 are formed above the silicon substrate 40.

The contact P ⁺ diffusion layer 41 is wired to a ground power supply. The metal thin film 42 is a metal thin film for forming a Schottky barrier diode, and is, for example, molybdenum (Mo). In order to electrically connect Mo with the silicon substrate 40 in an excellent manner, at least the interface portion with the silicon substrate 40 is silicided by heat treatment at about 500 ° C. The N-type diffusion layer 43 is a guard ring for preventing the Schottky barrier diode from breaking down at a low voltage in the peripheral portion. The transfer gate electrode 44 transfers electrons (charges) accumulated in the Schottky barrier diode to the N ⁺ diffusion layer 46. The N ⁺ diffusion layer 47 is connected to the power supply Vdd. The reset gate electrode 45 is an electrode for resetting the N ⁺ diffusion layer 46 to Vdd.

The N-channel MOS field effect transistor (FET) 48 is a source follower amplifier having a gate connected to the N ⁺ diffusion layer 46, a drain connected to Vdd, and a source serving as an output. The detected light 49 enters from the back surface of the silicon substrate 40. A non-reflective coating 50 made of a multilayer film is formed on the back surface of the silicon substrate 40 so that light is not reflected when incident. This is the pixel structure.

  The output of the pixel is held in capacitors 52 and 54 that function as memories through switching MOS FETs (hereinafter referred to as MOS switches) 51 and 53. The differential amplifier 55 amplifies the differential signal of the pixel readout signal held by the capacitors 52 and 54. The switching MOS FET (MOS switch) 56 outputs the pixel difference signal from the differential amplifier 55 to the outside at the timing when it is turned on.

Next, the operation of this pixel will be described with reference to the timing chart of FIG. Assume that electrons (charges) are accumulated in a Schottky barrier diode that has already entered the incident light and has the metal thin film 42 for a predetermined time. First, the reset gate electrode 45 is turned on for a predetermined time indicated by a high level in FIG. 10A, and the N ⁺ diffusion layer 46 becomes Vdd. Next, the MOS switch 51 is turned on for a predetermined time indicated by a high level in FIG. 10C, and the potential of the N ⁺ diffusion layer 46 is used as the offset signal through the source follower amplifier 48 and the MOS switch 51 to perform a memory function. To record.

Next, the transfer gate electrode 44 is turned on for a predetermined time indicated by a high level in FIG. 10B, and electrons (charges) accumulated in the Schottky barrier diode having the metal thin film 42 are transferred to the N ⁺ diffusion layer. 46 and the potential changes. Next, the MOS switch 53 is turned on for a predetermined time indicated by a high level in FIG. 10D, and the potential of the N ⁺ diffusion layer 46 is recorded in the capacitor 54 that performs the memory function through the source follower amplifier 48 and the MOS switch 53. .

  The operations so far are performed simultaneously for all the pixels of the linear sensor 1.

  Next, the read circuit 34 turns on the MOS switch 56 at a predetermined timing indicated by a high level in FIG. 10E, and the difference between each signal recorded in the capacitor 52 and the capacitor 53 output from the differential amplifier 55. The signal is output as a true signal and delivered to the A / D conversion circuit 35. The timing at which the MOS switch 56 is turned on differs depending on the pixel and is read sequentially. The reason why the difference signal between the signals recorded in the capacitor 52 and the capacitor 54 is output as a true signal is to remove the variation in the threshold voltage of the N-channel MOS FET 48 serving as the source follower amplifier. .

  Incidentally, the Schottky barrier diode having the metal thin film 42 has a problem that the dark current at the interface is larger than that of a photodiode using a normal PN junction. This dark current has the property of varying from pixel to pixel. Therefore, in order to remove the influence of the dark current, a dark current signal for each pixel is recorded in advance in a memory in a state where no optical signal is input, and a signal with less noise can be obtained by removing it from the signal.

  In addition, since the to-be-detected light 49 enters from the back surface of the silicon substrate 40 and is photoelectrically converted on the surface of the silicon substrate 40, visible light is absorbed by the silicon substrate 40 and only near infrared light is detected. Therefore, if it is desired to cut only visible light, the optical filter 4 is not necessary as described above.

  The metal used for the Schottky barrier diode is not limited to Mo, Sc, Er, Y, Ti, Hf, Mn, Zr, C (graphite), Nb, Cr, Co, Ni, Fe, W, Ta, Pd, Al, Rh, Be, Re, Ir, and Pt can be used.

  Now, the spectroscope body 5 of the spectroscope 10 made by stacking such 1 to 4 parts can be made to have a size of several millimeters in length, width, and height, and is very small. . Further, at that time, the tolerance for misalignment of parts is very high.

  For example, it is not necessary to adjust a specific pixel to measure a specific wavelength between the Fabry-Perot interferometer 2 and the linear sensor 1. This is because even a slight deviation can be easily corrected by the method shown in FIG. Here, a light source having a certain wavelength distribution with respect to the spectroscope body 5, for example, a light source 62 having a characteristic known to have a peak at 1.5 μm as shown by 63 is prepared. For example, an LED has a peak at a certain wavelength and has a wavelength-to-intensity characteristic in which the intensity decreases moderately as the wavelength moves away from the peak wavelength. Good.

  The diffusing plate 61 makes the light from the light source 62 enter the spectroscope body 5 with no variation in light intensity. As a result, a specific spectral distribution can be obtained, and it can be easily confirmed that the measurement wavelength of the pixel at which the signal intensity is maximum is 1.5 μm. When it is known, since it is known that the difference in measurement wavelength with the adjacent pixel is 10 nm, the measurement wavelengths of all the pixels are determined. If this correction result is recorded in the control circuit 36, for example, the readout circuit 34 can be appropriately controlled to output correct spectral characteristics.

  As described above, the spectroscope 10 according to the present embodiment requires a spatially smaller volume than the spectroscope described in Patent Document 1, is integrated, and is resistant to vibration, and the variable interferometer described in Patent Document 2 It is a small-sized spectroscope that can be carried without requiring a large voltage as in a spectroscope using a laser. In addition, although the spectrometer 10 of the present embodiment is an optical component, it is resistant to misalignment and thus greatly contributes to the cost reduction of the spectrometer.

  Since the spectroscope according to the present invention is a small and light infrared spectroscope, it is particularly effective for obtaining spectral characteristics in biological systems and medical sites, and can be used for, for example, a blood glucose level sensor.

DESCRIPTION OF SYMBOLS 1 Linear sensor 2 Fabry-Perot interferometer 3 Beam collimating device 4 Optical filter 5 Spectrometer main body 6 Light source 7 Object to be measured 10 Spectroscope 20a, 20b, 24, 25 Dielectric 21a, 21b Spacer 22a, 22b Multilayer film 23a, 23b Reflection surface 31 hole 32 sheet 33 chip 34 readout circuit 35 A / D conversion circuit 36 control circuit 37 power supply circuit 38 I / O circuit 39 pad 40 silicon substrate 41 contact P ⁺ diffusion layer 42 metal thin film 43 N-type diffusion layer 44 transfer Gate electrode 45 Reset gate electrode 46, 47 N ⁺ diffusion layer 48 N-channel MOS field effect transistor (source follower amplifier)
51, 53, 56 MOS field effect transistor for switching 52, 54 Capacitor 55 Differential amplifier

Claims (7)

A linear sensor in which a plurality of pixels having sensitivity in a predetermined wavelength range are linearly arranged at a predetermined pitch;
A Fabry-Perot interferometer that has a characteristic of changing a resonance wavelength with respect to a direction parallel to an arrangement direction of the plurality of pixels constituting the linear sensor, and that splits incident light and enters the linear sensor;
Beam collimating means for collimating incident light on the Fabry-Perot interferometer;
A spectroscope comprising: a light source that makes the light to be detected incident on the light collimating means.   The spectroscope according to claim 1, further comprising an optical filter that removes an unnecessary wavelength of light incident on the linear sensor between the linear sensor and an object to be measured.   In the Fabry-Perot interferometer, both ends of the flat plate-like first and second dielectrics whose reflecting surfaces formed on one surface are opposed to each other are fixed, and the first and second dielectrics The resonance wavelength distribution is formed by arranging the intervals so as to linearly change from one fixed end interval to the other fixed end interval. The spectroscope according to 1 or 2.   The beam collimating means comprises a sheet having a plurality of holes, and each of the plurality of holes has an axial length larger than a maximum length of a transverse section perpendicular to the axial direction. The spectroscope according to any one of claims 1 to 3, wherein the spectroscope has a length and an inner side surface is in a non-reflective state.   In the linear sensor, each of the plurality of pixels includes a Schottky barrier diode having a structure in which a metal is in contact with the surface of the substrate, and light enters through the Fabry-Perot interferometer from the back surface of the substrate. The spectroscope according to any one of claims 1 to 4, wherein the spectroscope has a configuration. Transfer means for transferring charges accumulated in the Schottky barrier diode to a high-concentration diffusion layer having a conductivity type opposite to that of the substrate;
The spectroscope according to claim 5, further comprising: readout circuit means for reading out a potential change accumulated in the high concentration diffusion layer as a signal. The light source is a light source that emits light whose peak wavelength is known in advance,
A diffusion plate that diffuses light from the light source and enters the light collimating means;
Among the plurality of pixels, the pixel having the maximum intensity of the readout signal is identified as the pixel measuring the peak wavelength, and based on the difference in the known measurement wavelength between the identified pixel and the adjacent pixel The spectroscope according to any one of claims 1 to 6, further comprising specifying means for specifying the measurement wavelength for all of the plurality of pixels.