JP2011117884A - Spectrophotometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spectrophotometer acquiring a continuous spectrum with high reliability over a wide measurement wavelength band in spite of its small size. <P>SOLUTION: This spectrophotometer using Fabry-Perot filters 110 each made by oppositely disposing first and second, two mirrors 111 and 112 parallel to each other with an air layer of a prescribed thickness interposed between them, includes a plurality of sensor units 10 each equipped in a one-to-one relation with the Fabry-Perot filter 110 and an infrared detection element 122 for receiving an infrared light passing through the Fabry-Perot filter 110 to output a light reception signal corresponding to the amount of light received. The sensor units 10 are juxtaposed on the same support substrate, with the infrared passbands of respective Fabry-Perot filters 110 made different from each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a spectrometer using a Fabry-Perot filter, and more particularly to a spectrometer capable of obtaining a continuous spectrum over a wide measurement wavelength band while being small.

  The Fabry-Perot filter is an element composed of a transparent parallel mirror having two reflecting surfaces, and is mainly used for analyzing the gas concentration in the atmosphere.

  As an example, the spectrometer described in Patent Document 1 includes a strip-shaped light guide having an ATR (Attenuated Total Reflection) crystal, and a linear infrared ray is provided at one end of the light guide. A light source is disposed, and an optical filter array and an infrared sensor array that detects infrared rays transmitted through the optical filter array are disposed on the other end side of the light guide.

  The optical filter array is an LVF (Linear Variable Filter), and filter elements having different transmitted light wavelengths are continuously formed on a band-shaped filter substrate. Specifically, the filter thickness is continuously different, and there is a proportional relationship between the transmitted light wavelength and the position on the filter, and the infrared sensor array has a one-to-one correspondence with each filter. Elements are arranged.

  Infrared light emitted from the linear infrared light source passes through the ATR crystal while being totally reflected, and after being dispersed by the optical filter array, is incident on the infrared sensor array and detected. When reflection is repeated in the ATR crystal, the sample on the surface of the crystal has a weak absorption of light and the light is attenuated. Since the wavelength of the attenuated light differs depending on the sample, the substance can be identified by spectroscopy.

  Further, in Patent Document 2, in a Fabry-Perot filter having first and second parallel mirrors, an electrode is provided for each mirror, and the thickness of the air layer is changed by a voltage applied between the electrodes, thereby producing a Fabry. An invention has been proposed in which the transmission wavelength band of a Perot filter can be varied in three stages.

US Pat. No. 6,420,708 JP 2001-228326 A

  The spectrometer described in Patent Document 1 is highly reliable because it is a completely solid type, but since one sensor element is assigned to one wavelength band, the measurement wavelength band is widened (or wavelength resolution). In order to improve the above, it is necessary to increase the number of elements of the infrared sensor array. Similarly, the optical filter array (LVF) must be lengthened. This means that the spectrometer itself becomes large, which is not preferable from the viewpoint of manufacturing.

  On the other hand, according to the invention described in the above-mentioned Patent Document 2, one Fabry-Perot filter can cover, for example, three transmission wavelength bands, but the wavelength range that can be dispersed is still narrow and practical. Absent. Moreover, even if the thickness of the air layer is changed by the voltage applied between the electrodes, there is a problem that the control is not easy and the reliability is poor.

  Accordingly, an object of the present invention is to provide a spectroscopic measuring device that can obtain a continuous spectrum with high reliability over a wide measurement wavelength band while being small in size.

  In order to solve the above-mentioned problems, the present invention provides a spectrometer using a Fabry-Perot filter in which first and second mirrors are arranged in parallel and face each other through an air layer having a predetermined thickness. A plurality of sensor units comprising a one-to-one relationship between the Fabry-Perot filter and an infrared detection element that receives infrared light transmitted through the Fabry-Perot filter and outputs a light reception signal corresponding to the amount of light received; Each Fabry-Perot filter has a different infrared transmission band, and the sensor units are juxtaposed on the same support substrate.

  According to a preferred aspect of the present invention, the range of the measurement wavelength band required for the spectrometer is m, the number of sensor units is n, and the width of the infrared transmission band assigned to each Fabry-Perot filter is approximately m / n, and the measurement wavelength band is covered by the whole of the plurality of sensor units.

  In the present invention, it is preferable that each of the mirrors is formed of a multilayer optical thin film formed by laminating a high refractive material and a low refractive material each having a predetermined thickness.

  Further, a long pass filter and a sapphire substrate are preferably laminated on the first mirror on the infrared incident side.

  More preferably, the sapphire substrate is laminated on the first mirror via the long pass filter, and the sapphire substrate is coated with an antireflection film.

  The long pass filter is preferably formed of Ge and / or ZnS having a predetermined thickness.

  The sensor units are preferably arranged in a matrix of multiple columns and multiple rows.

  Moreover, it is preferable that the sensor unit which exists in the center part of each said sensor unit is arrange | positioned on the optical axis of an infrared light source.

  According to the present invention, a plurality of sensor units each provided with a Fabry-Perot filter and an infrared detection element having different infrared transmission bands in a one-to-one relationship are juxtaposed on the same support substrate. The wavelength band that can be measured by the number of units can be expanded.

  Moreover, since each Fabry-Perot filter is a complete solid type, high reliability can be obtained. In terms of manufacturing, since the infrared detection element side of each sensor unit can be shared, the cost can be reduced accordingly.

  In addition, when each sensor unit is arranged in a matrix of multiple columns and multiple rows, each sensor unit and the infrared light source are arranged by arranging the sensor unit present in the center portion on the optical axis of the infrared light source. Can be made substantially equal to each other, and the reliability of the measurement is further improved.

The external appearance perspective view which shows the spectrometer which concerns on embodiment of this invention. The typical sectional view showing the sensor unit contained in the above-mentioned spectroscopic measuring device. The typical exploded sectional view showing the above-mentioned sensor unit. The graph which shows an example of the measurement wavelength band of the said spectrometer.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited to this.

  As shown in FIG. 1, the spectrometer 1 according to this embodiment has, for example, nine sensor units 10 (10a to 10i) each having a Fabry-Perot filter arranged two-dimensionally on the same support substrate 20. It becomes. In this embodiment, each sensor unit 10 has a size of about 3 mm square and is arranged in a matrix of 3 rows × 3 columns.

  Each sensor unit 10 has the same configuration except that the infrared transmission band of the Fabry-Perot filter is different, and the configuration will be described with reference to FIGS.

  Each sensor unit 10 includes a filter unit 11 and a sensor unit 12. In this embodiment, the filter unit 11 includes a Fabry-Perot filter 110, a long pass filter 114, and a sapphire substrate 115.

  The Fabry-Perot filter 110 is composed of a first mirror 111 on the light incident side and a second mirror 112 on the light emission side which are arranged opposite to each other in parallel with a spacer 113 interposed therebetween. The space between the first mirror 111 and the second mirror 112 is an air layer G.

  In this embodiment, the first mirror 111 is composed of a multilayer optical thin film having a three-layer structure in which the Ge layer, the ZnS layer, and the Ge layer are laminated in order from the top in FIG.

  The second mirror 112 is formed of a multilayer optical thin film having a three-layer structure in which the Ge layer, the ZnS layer, and the Ge layer are sequentially stacked from the top in FIG.

  In this embodiment, in each of the first mirror 111 and the second mirror 112, each Ge layer is 210 nm thick, each ZnS layer is 420 nm thick, and the total thickness of the first mirror 111 is 840 nm. The total thickness of 112 is 840 nm.

  In this embodiment, Ge is used as the high-refractive material and ZnS is used as the low-refractive material. However, the selection and combination of the refractive materials can be performed by a machine such as a measurement range and a thermal expansion coefficient required for the spectrometer 1. It is determined in consideration of the characteristics.

For reference, an example of a refractive material applicable to each of the mirrors 111 and 112 and a refractive index thereof are shown in Table 1 below.

  In this embodiment, the spacer 113 is made of silicon resin, and the air layer G is 1850 nm. The long pass filter 114 is for removing unnecessary portions on the short wavelength side. For example, the odd layer may be made of Ge and the even layer may be made of ZnS, and desired filter characteristics can be obtained by combining these layers.

  The sapphire substrate 115 removes unnecessary wavelengths on the long wavelength side by absorption of the substrate itself. The sapphire substrate 115 is preferably coated with an anti-reflection film.

  The sensor unit 12 includes a silicon substrate 121 formed to be approximately the same size as the sapphire substrate 115, and an infrared sensor 122 is mounted on the silicon substrate 121. The infrared sensor 122 is preferably a thermal infrared sensor such as a pyroelectric sensor, a thermopile, or a bolometer in order to enable measurement over a wide wavelength range.

  The filter unit 11 and the sensor unit 12 are manufactured in separate processes, and are integrally bonded via a bump bonding portion 123 as shown in FIG. Since the sensor unit 12 may be used in common for each of the sensor units 10a to 10i, the production cost can be reduced accordingly.

  In the manufacturing process of the filter unit 11, the long pass filter 114 is formed on the sapphire substrate 115, and the Fabry-Perot filter 110 is formed thereon.

  In forming the Fabry-Perot filter 110, the materials and thicknesses of the first mirror 111 and the second mirror 112 and the thickness of the air layer G are appropriately determined so that the infrared transmission band is different for each of the sensor units 10a to 10i. .

  Referring to the graph of FIG. 4 (horizontal axis λ; wavelength, vertical axis T; transmittance), the gas to be measured is irradiated with infrared light from a light source (not shown), and the contained gas component is measured by dispersing the passing light. In this case, assuming that the spectral range required for the spectrometer 1 is, for example, about 10 μm, in this embodiment, as shown by the horizontal axis in FIG. 4, each sensor unit 10 a to 10 i has a transmission band of about 1 μm. Give width.

  That is, about 0 to 1 μm for the sensor unit 10a, 1 to 2 μm for the sensor unit 10b, 2 to 3 μm for the sensor unit 10c, 3 to 4 μm for the sensor unit 10d, and so on. Provide different transmission bandwidths of about 1 μm.

  Moreover, the light reception signal output from the infrared sensor 122 of each sensor unit 10a-10i is input into the measurement circuit which is not shown in figure via a multiplexer, for example. According to this, a continuous spectrum as shown in FIG. 4 can be obtained by sequentially switching the multiplexers at high speed.

  According to the high-speed switching of the multiplexer, as shown in FIG. 1, it is not necessary to arrange the sensor units 10a to 10i in order, and the sensor units 10a to 10i are randomly arranged on the support substrate 20. Good.

  In the above embodiment, nine sensor units 10 are arranged in a matrix of 3 rows × 3 columns on the support substrate 20, but the number and arrangement of the sensor units 10 may be arbitrarily determined.

  In addition, in order to make the distance between the light source (not shown) and each sensor unit 10 as uniform as possible, the sensor units 10 arranged at the center of the plurality of sensor units 10 arranged in a matrix (in the embodiment of FIG. The unit 10e) is preferably arranged on the optical axis of the light source.

DESCRIPTION OF SYMBOLS 1 Spectrometer 10 (10a-10i) Sensor unit 11 Filter part 110 Fabry-Perot filter 111 1st mirror (light incident side)
112 Second mirror (light exit side)
113 Spacer 114 Long pass filter 115 Sapphire substrate 12 Sensor unit 121 Silicon substrate 122 Infrared sensor 123 Bump joint 20 Support substrate G Air layer

Claims (8)

In a spectrophotometer using a Fabry-Perot filter in which the first and second mirrors are parallel to each other and arranged opposite to each other through an air layer of a predetermined thickness,
A plurality of sensor units comprising a one-to-one relationship between the Fabry-Perot filter and an infrared detection element that receives infrared light transmitted through the Fabry-Perot filter and outputs a light reception signal corresponding to the amount of light received; Each of the Fabry-Perot filters has a different infrared transmission band, and the sensor units are juxtaposed on the same support substrate.   The range of the measurement wavelength band required for the spectrometer is m, the number of sensor units is n, the width of the infrared transmission band assigned to each Fabry-Perot filter is approximately m / n, and the plurality of sensors The spectroscopic measurement device according to claim 1, wherein the entire measurement wavelength band is covered by the unit.   3. The spectrophotometer according to claim 1, wherein each of the mirrors comprises a multilayer optical thin film formed by laminating a high refractive material and a low refractive material each having a predetermined thickness.   The spectrophotometer according to any one of claims 1 to 3, wherein a long pass filter and a sapphire substrate are laminated on the first mirror on the infrared incident side.   The spectrophotometer according to claim 4, wherein the sapphire substrate is laminated on the first mirror through the long pass filter, and the sapphire substrate is coated with an antireflection film.   The spectrophotometer according to claim 4 or 5, wherein the long pass filter is formed of Ge and / or ZnS having a predetermined thickness.   7. The spectrophotometer according to claim 1, wherein each of the sensor units is arranged in a matrix of multiple columns and multiple rows.   8. The spectrophotometer according to claim 7, wherein the sensor unit existing at the center of each sensor unit is disposed on the optical axis of an infrared light source.

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