JP2008026127A - Spectral unit, and meteorological observation lidar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the precision of measurement of a Raman lidar system. <P>SOLUTION: The spectral unit is equipped with: a diffraction grating (32) for generating diffraction light on the basis of object light; two wedge mirrors (35, 36) arranged with a gap between on the optical path of the diffraction light; first interference filters (44, 45) arranged on the optical path of transmitted light passing through the gap between the two wedge mirrors; and second interference filters (38, 39) arranged on the optical path of reflected light generated by at least one of the two wedge mirrors. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in measurement technology used for measurement according to optical phenomena such as reflection, absorption, and scattering of atmospheric components.

  LIDAR (Light Detection and Ranging) is a technology that observes the state of the atmosphere by irradiating a short pulse of laser light in the atmosphere of the observation area and measuring and analyzing the scattered light as a lidar signal. . As a laser beam for lidar observation, an Nd: YAG laser is usually used. The types of scattering by laser light irradiation include Mie scattering by aerosol (floating particulate matter), Rayleigh scattering and Raman scattering by atmospheric constituent molecules, and using these, atmospheric temperature, aerosol spatial distribution, atmospheric density It is possible to analyze observation elements such as concentration distribution of atmospheric components. Specifically, this analysis is performed by solving a so-called rider equation expressing a rider signal (see, for example, Patent Document 1).

In measurement by a rider, it is necessary to perform measurement according to optical phenomena such as reflection, absorption, and scattering of atmospheric components to be measured. For example, in the case of temperature measurement using rotational Raman scattering of “air” composed of nitrogen molecules, oxygen molecules, etc., temperature measurement is performed by detecting narrow-band response signals at at least two adjacent central wavelengths. Can be realized. In addition to these temperature lidars, Raman lidar for the purpose of detecting the concentration of atmospheric gas substances (H ₂ O, SOx, NOx, CH ₄ etc.) has at least a narrow-band response signal at such a unique central wavelength. One or more must be detected.

  In conventional Raman lidar technology, the efficiency of the entire optical system and the blocking rate of light other than the target wavelength are issues, and as a means to overcome this, there is a method of using multiple high-performance interference filters. Has been used. However, a high-performance interference filter is expensive, and the cost of the entire measurement system is high. Furthermore, since the laser in the visible range is used and the safety to the eyes (eye-safe performance) is low, the laser output is limited. There was an inconvenience of a drop.

International Publication Number WO 03/073127 A1

Therefore, the present invention guides Raman scattered light with higher reception efficiency before guiding incident light of two adjacent central wavelengths to the detector, and higher blocking rate of Raman scattered light from Mie scattered light and Rayleigh scattered light. The purpose is to improve the measurement accuracy.
Another object of the present invention is to reduce the cost of a Raman rider system.

The spectroscopic unit according to the first aspect of the present invention includes:
A diffraction grating that generates diffracted light based on the target light;
Two wedge mirrors provided so that a gap is provided between them, and the optical path of the diffracted light passes through the gap;
A first interference filter disposed on an optical path of light passing through the gap between the two wedge mirrors;
A second interference filter disposed on an optical path of reflected light generated by at least one of the two wedge mirrors;
It is characterized by providing.
Here, the “wedge mirror (wedge mirror)” is a member (for example, a plate-like member) having an action of reflecting incident light, in which the end of the member is formed at an acute angle. Say.

  In the above configuration, two wedge mirrors are arranged with a minute gap between each other (between each end), and are used like a slit, thereby increasing the wavelength of spatial proximity. Spectroscopy is performed by the blocking rate. It is possible to improve the measurement accuracy by effectively utilizing such a high cutoff rate of the near wavelength by the wedge mirror, high efficiency by the diffraction grating, and high efficiency and cutoff rate by the interference filter. In addition, by using relatively inexpensive diffraction gratings and wedge mirrors, the number of more expensive interference filters used can be reduced as compared with the prior art, so that the measurement system can be simplified and the cost can be reduced. .

  Preferably, the two wedge mirrors are arranged such that the extending directions of the two wedge mirrors intersect obliquely. More specifically, it is preferable that the two wedge mirrors are disposed so that the reflecting surfaces of the two wedge mirrors as a whole are concave with respect to the incident direction of the diffracted light. It is also preferable that the two wedge mirrors are arranged so that the reflecting surfaces of the two wedge mirrors as a whole are convex with respect to the incident direction of the diffracted light.

  This makes it easier to receive the reflected light generated by each wedge mirror.

  Preferably, the spectroscopic unit is disposed between the diffraction grating and the two wedge mirrors on the optical path of the diffracted light, and condenses the diffracted light in the vicinity of the gap between the two wedge mirrors. A first lens is further provided.

  Thereby, the spectral accuracy (resolution) can be further increased.

  Preferably, the spectroscopic unit further includes a second lens that is disposed on the optical path of the target light and disposed between the incident position of the target light and the diffraction grating, and converts the target light into parallel light. Prepare.

  Thereby, the light use efficiency of object light can be improved and measurement accuracy can be improved more.

Preferably, the spectroscopic unit is
A first light receiver disposed on the optical path of the passing light and subsequent to the first interference filter;
A second light receiver disposed on the optical path of the reflected light and subsequent to the second interference filter;
Is further provided.

The meteorological observation lidar system according to the second aspect of the present invention is:
A transmission unit that generates pulsed laser light and launches it toward the atmosphere to be observed;
A receiving unit that receives reflected light from the atmosphere of the laser light emitted from the transmitting unit as observation target light; and
A spectroscopic unit that splits the observation target light received by the receiving unit to generate a plurality of signal lights, and converts the plurality of signal lights into electrical signals, respectively;
A control / processing unit that controls operations of the transmission unit, the reception unit, and the spectroscopic unit, and that performs signal processing based on the electrical signal output from the spectroscopic unit;
Including
The spectroscopic unit is used as the spectroscopic unit.

  According to the above configuration, a rider system with high measurement accuracy, a simple system, and low cost can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the measurement precision of a rider system, the simplification and cost reduction of a measurement system can be achieved.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing a basic configuration of a weather observation lidar system. The meteorological observation lidar system 100 generates a single pulse laser beam suitable for lidar observation, and emits the laser beam toward the atmosphere to be observed, and the laser light emitted from the transmission unit 1. Receiving unit 2 that receives reflected light (scattered light) from the atmosphere as a response signal (rider signal), and the response signal received by the receiving unit 2 is used as a response signal (observation target light) necessary for various lidar observations Each of the spectral units generates a plurality of signal lights and converts each of the signal lights into electrical signals, and controls the devices that constitute each of these units, and the electrical signals output from the spectral unit 3 And a control / processing unit 5 that performs analysis processing for each observation element in the observation region.

  The laser device 11 that forms the core of the transmission unit 1 includes a Q-switched Nd / YAG laser. The laser device 11 takes out the third harmonic component (λ = 355 nm) of the generated laser light of the high-frequency pulse by a non-illustrated nonlinear optical element and emits appropriate output energy to the outside.

  Laser light emitted from the laser device 11 is adjusted to an appropriate diameter via the beam expander 14 and then emitted from a predetermined position toward the atmosphere. By enlarging the beam diameter using the beam expander 14, it is possible to reduce the spread of the beam emitted to the upper atmosphere and improve the condensing efficiency finally obtained.

  The receiving unit 2 is a reflecting telescope that collects reflected light (backscattered light) of laser light emitted toward the atmosphere. Observation light (response signal) collected by the reflecting telescope is guided to the spectroscopic unit 3 through an optical fiber.

  The spectroscopic unit 3 is configured to be able to detect and separate the response signals introduced from the receiving unit 2 via the optical fiber 6 into signals necessary for lidar observation. Response signals (electrical signals) respectively detected by the respective light detection means (not shown) of the spectroscopic unit 3 are converted into digital signals by the analog / digital device (A / D converter) 4 and are sent to the control / processing unit 5. Sent out and analyzed. Thereby, atmospheric temperature, water vapor amount, aerosol distribution, and the like are obtained.

  The control / processing unit 5 includes a display 17, a keyboard 18, and a printer 19 with a computer 16 as a center. The computer 16 is provided with an input / output port. The computer 16 receives signals sent from the devices constituting each unit via the input / output ports, and sends signals to the devices. Output each. The basic role of the computer 16 is to control the atmospheric temperature, water vapor, and other states based on response signals from the respective light detection means of the spectroscopic unit 3 under comprehensive control over the weather observation lidar system of the present embodiment. To analyze.

  FIG. 2 is a diagram for explaining the configuration of the spectroscopic unit 3. The observation light (target light) guided from the receiving unit 2 via the optical fiber 6 is backscattered light from the atmosphere above. Such scattered light is incident on a lens 31 disposed on the optical path between the diffraction grating 32 and the incident position of the scattered light (one end of the optical fiber 6 in this example). The scattered light is converted into parallel light by passing through the lens 31 and then enters the diffraction grating 32. The incident light is reflected as light (diffracted light) for each wavelength by the diffraction grating 32, and is guided to the wedge mirror unit 34 through the lens 33. The wedge mirror unit 34 includes two wedge mirrors 35 and 36. Here, the “wedge mirror” refers to a wedge-shaped member (for example, a plate-shaped member) that has an action of reflecting incident light, and an end portion of the member is formed at an acute angle. The wedge mirrors 35 and 36 are provided with a slight gap (for example, about several hundred μm) between the end portions thereof, and are arranged so that the gap is located on the optical path of the diffracted light. And these wedge mirrors 35 and 36 are arrange | positioned so that the mutual extension direction may cross diagonally. Details of the arrangement of the wedge mirror 34 will be described later.

  The lens 37, the two interference filters 38 and 39, and the lens 40 are arranged in this order on the optical path of the light (reflected light) reflected by one wedge mirror 35. The reflected light from the wedge mirror 35 is converted into parallel light by passing through the lens 37, passes through the two interference filters 38 and 39, and is further collected by the lens 40. Note that only one interference filter may be used depending on its characteristics. The light collected by the lens 40 is received by the detector 41 and converted into an electric signal corresponding to the intensity. The electrical signal (analog signal) output from the detector 41 is converted into a digital signal by the A / D converter 4 described above and transferred to the computer 16. The light reflected by the other wedge mirror 36 (reflected light) is absorbed by a damper 42 disposed on the optical path of the reflected light.

  The lens 43, the two interference filters 44 and 45, and the lens 46 are arranged in this order on the optical path of the light (passing light) that has passed through the gap between the two wedge mirrors 35 and 36. The passing light is converted into parallel light by passing through the lens 43, passes through the two interference filters 44 and 45, and is collected by the lens 46. Note that only one interference filter may be used depending on its characteristics. The light condensed by the lens 46 is received by the detector 47 and converted into an electric signal corresponding to the intensity. The electrical signal (analog signal) output from the detector 47 is converted into a digital signal by the A / D converter 4 described above and transferred to the computer 16.

また、回折格子３２によって生じる回折光の回折角θ_out（λ）は、回折次数をｍとすると次式のように表される。

よって、設計によりθ_out（λ₀）の角度を定義する。例えば、＋１次回折光を用いるとするとｍ＝＋１となるので、レーザ光の入射角θ_inを適宜設定することにより、θ_out（λ₀）の値が求められる。この求められたθ_out（λ₀）の値に基づき、＋１次回折光の進行方向（光路）が分かるので、当該進行方向に対応してレンズ３３及びウェッジミラー部３４を配置する。 FIG. 3 is a diagram for explaining the details of the diffraction grating 32. In the present embodiment, a reflective blazed diffraction grating is used as the diffraction grating 32, which is schematically shown in FIG. The wavelength of the laser beam (laser beam) emitted from the optical fiber 4 and incident on the diffraction grating 32 is λ ₀ , and the incident angle of the laser beam (that is, the crossing angle between the perpendicular of the main surface of the diffraction grating 32 and the laser beam) θ. _In , where the grating constant of the diffraction grating 32 is N, the incident angle θ _in of the laser beam is expressed by the following equation.

Further, the diffraction angle θ _out (λ) of the diffracted light generated by the diffraction grating 32 is expressed by the following equation where the diffraction order is m.

Therefore, the angle of θ _out (λ ₀ ) is defined by design. For example, if + 1st order diffracted light is used, m = + 1. Therefore, the value of θ _out (λ ₀ ) can be obtained by appropriately setting the incident angle θ _in of the laser light. Since the traveling direction (optical path) of the + 1st-order diffracted light is known based on the obtained value of θ _out (λ ₀ ), the lens 33 and the wedge mirror unit 34 are arranged corresponding to the traveling direction.

FIG. 4 is a diagram for explaining details of the arrangement of the wedge mirror unit 34. In FIG. 4, the gap portion between the wedge mirrors 35 and 36 is shown enlarged. First, each of the wedge mirrors 35 and 36 is disposed in a state in which both reflecting surfaces are concave with respect to the light incident direction (upper left in the drawing). More specifically, if the crossing angle formed by the extension directions of the wedge mirrors 35 and 36 is φ as shown in the figure, φ is appropriately set within a range of approximately 90 ° to 180 °. In this embodiment, the intersection angle between the wedge mirror 35 and the wedge mirror 36 is set to φ = 135 °. The wedge mirrors 35 and 36 are arranged so that the edge surfaces (end portions) 35a and 36a do not face the light incident direction. In other words, the wedge mirrors 35 and 36 are arranged such that their upper surfaces (long side sides) 35b and 36b face each other in the light incident direction. Thereby, unnecessary reflected light (stray light) can be prevented from being generated at the edge portion. In addition, the wedge mirrors 35 and 36 are arranged apart from each other with a certain gap therebetween. More specifically, light having a wavelength λ ₀ is reflected by the wedge mirror 36, and light having a shorter wavelength λ ₋₁ passes through the gap between the wedge mirrors 35, 36, and further has a shorter wavelength λ ₋₂ . The arrangement state of each of the wedge mirrors 35 and 36 is set so that the light is reflected by the wedge mirror 35. As a result, the light having the wavelength λ ₋₁ that has passed through the gap between the wedge mirrors 35 and 36 passes through the lenses 43 and 46 and the interference filters 44 and 45, and is detected by the detector 47. The light having the wavelength λ _-2 reflected by the wedge mirror 35 passes through the lenses 37 and 40 and the interference filters 38 and 39 and is detected by the detector 41. The light having the wavelength λ ₀ reflected by the wedge mirror 36 is absorbed by the damper 42. It is desirable that the intersection angle φ of each of the wedge mirrors 35 and 36 is arranged so that the reflection efficiency of the light having the wavelength λ _{0 and} the light having the wavelength λ _-2 is maximized. As for the gap between the wedge mirrors 35 and 36, the wavelength of the light to be used (for example, in this example, the wavelengths λ ₀ , λ ₋₁ , and λ ₋₂ are 354.67 nm, 354.10 nm, and 353.10 nm, respectively). In addition, it is appropriately set according to the characteristics of the diffraction grating 32 and the lens 33, and an interval of about several hundred μm is provided, for example. This will be further described.

ここで、ｆはレンズ３３の焦点距離、ｄはスポット位置（像高）である。また、短波長側の回折光の波長をλ_-1、λ_-2、・・・、λ_-n、長波長側の回折光の波長をλ₁、λ₂、・・・、λ_n、と表現する。このとき、中心波長λ₀、短波長側の波長λ_-1、長波長側の波長λ₁、のそれぞれに対するスポット位置ｄ（λ₀）、ｄ（λ_-1）、ｄ（λ₁）は図示のように、レンズ３３の光軸と直交する面（像面）において微小距離だけ離間する。本実施形態の気象観測ライダーシステム１００では、中心波長λ₀、短波長側波長λ_-1の光を受信する。このとき、短波長側の光の受信スペクトル幅をΔλ_-1とすると、ウェッジミラー３５、３６の相互間の間隔ｄ１は次式によって表される。

よって、この（４）式に基づいて、各ウェッジミラー３５、３６の相互間距離を設定することができる。このように、２枚のウェッジミラーを相互間に微小な間隙を設けつつ配置し、スリットのようにして用いることにより、空間的に近接している波長を高い遮断率で分光することが可能となる。 FIG. 5 is a diagram for explaining in detail the interval between the wedge mirrors 35 and 36. In FIG. 5, the relationship between the incident light to the lens 33 and the spot position of the outgoing light from the lens 33 is shown. The basic formula for the spot position is expressed as follows. In the following equation (3), theta _out is approximated to tanθ _out ≒ _{θ out} because it is very small.

Here, f is the focal length of the lens 33, and d is the spot position (image height). Further, _-1 wavelength of the diffracted light on the short wavelength side _{λ, λ -2, ···, λ} -n, the wavelength of the diffracted light on the long wavelength side _{λ 1, λ 2, ···,} λ n, and Express. At this time, the center wavelength lambda _0, the wavelength lambda _-1 on the short wavelength side, the wavelength lambda ₁ of the long wavelength side, the spot position for each _{d (λ 0), d (} λ -1), d (λ 1) is shown As described above, the lens 33 is separated by a minute distance on the surface (image surface) orthogonal to the optical axis. The meteorological observation lidar system 100 of the present embodiment receives light having a center wavelength λ ₀ and a short wavelength λ ₋₁ . At this time, assuming that the reception spectrum width of the light on the short wavelength side is Δλ ₋₁ , the interval d1 between the wedge mirrors 35 and 36 is expressed by the following equation.

Therefore, the mutual distance between the wedge mirrors 35 and 36 can be set based on the equation (4). In this way, by arranging two wedge mirrors with a small gap between them and using them like slits, it is possible to disperse spatially close wavelengths with a high cutoff rate. Become.

  The meteorological observation lidar system 100 of the present embodiment has the above-described configuration. Next, another configuration example of the above-described spectroscopic unit 3 will be described. The meteorological observation lidar system 100 of the present embodiment can also be configured using a spectroscopic unit 3a described below.

  FIG. 6 is a diagram illustrating another configuration example of the spectroscopic unit. The basic configuration of the spectroscopic unit 3a shown in FIG. 6 is the same as that of the spectroscopic unit 3 shown in FIG. In addition, the same code | symbol is attached | subjected about the component which is common in the spectroscopy unit 3 mentioned above and the spectroscopy unit 3a of this example, and detailed description about them is abbreviate | omitted. The spectroscopic unit 3 a of this example is different from the spectroscopic unit 3 in the arrangement state of the wedge mirrors 35 and 36 included in the wedge mirror unit 34. In addition, with the change in the arrangement state of the wedge mirror section 34, the arrangement of the optical system including the lenses 37 and 40, the interference filters 38 and 39, and the detector 41 and the arrangement of the damper 42 are switched.

FIG. 7 is a diagram for explaining in detail the arrangement state of the wedge mirror 34 in the spectroscopic unit shown in FIG. In FIG. 7, a gap portion between the wedge mirrors 35 and 36 is shown enlarged. First, in this example, each of the wedge mirrors 35 and 36 is arranged in a state in which both reflecting surfaces are convex with respect to the incident direction of diffraction light (upper left in the drawing). More specifically, if the crossing angle formed by the extension directions of the wedge mirrors 35 and 36 is φ as shown in the figure, φ is appropriately set within a range of approximately 90 ° to 180 °. In this embodiment, the intersection angle between the wedge mirror 35 and the wedge mirror 36 is set to φ = 135 °. That is, the arrangement shown in FIG. 4 is inverted. The wedge mirrors 35 and 36 are arranged so that the edge surfaces 35a and 36a do not face the light incident direction. In other words, the wedge mirrors 35 and 36 are arranged such that their upper surfaces (long side sides) 35b and 36b face each other in the light incident direction. In other words, in the example shown in FIG. 4, the angle formed by the upper surfaces 35b and 36b is 90 ° to 180 °, but in this example, the angle formed by the upper surfaces 35b and 36b (vertical angle of φ) is 180 °. It is in a range of ˜270 °. Thereby, unnecessary reflected light (stray light) can be prevented from being generated at the edge portion. In addition, the wedge mirrors 35 and 36 are arranged apart from each other with a certain gap therebetween. Since the setting method of the gap is as described above, the description is omitted here (see FIG. 5). Also in this example, the light with the wavelength λ ₀ is reflected by the wedge mirror 36, and the light with the shorter wavelength λ ₋₁ passes through the gap between the wedge mirrors 35, 36, and further has the shorter wavelength λ ₋₂ . The arrangement state of each of the wedge mirrors 35 and 36 is set so that the light is reflected by the wedge mirror 35. The light having the wavelength λ ₋₁ that has passed through the gap between the wedge mirrors 35 and 36 passes through the lenses 43 and 46 and the interference filters 44 and 45, and is detected by the detector 47. The light having the wavelength λ _-2 reflected by the wedge mirror 35 passes through the lenses 37 and 40 and the interference filters 38 and 39 and is detected by the detector 41. The light having the wavelength λ ₀ reflected by the wedge mirror 36 is absorbed by the damper 42.

  As described above, in this embodiment, two wedge mirrors are arranged with a small gap between each other and are used like a slit, so that spatially close wavelengths can be separated with a high cutoff rate. is doing. It is possible to improve the measurement accuracy by effectively utilizing such a high cutoff rate of the near wavelength by the wedge mirror, high efficiency by the diffraction grating, and high efficiency and cutoff rate by the interference filter. In addition, by using relatively inexpensive diffraction gratings and wedge mirrors, the number of more expensive interference filters used can be reduced as compared with the prior art, so that the measurement system can be simplified and the cost can be reduced. .

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change in various further and can be implemented. For example, in the embodiment described above, a reflective blazed diffraction grating is used as the diffraction grating 32, but a transmissive diffraction grating may be used as the diffraction grating 32. In this case, it is well known to those skilled in the art that in the optical system shown in FIG. 2 and the like, the incident direction of the laser light may be set on the side opposite to the illustrated example.

  The diffraction grating 32 does not necessarily have to be a blazed type, and may have another form. In addition, the traveling direction of the reflected light by each wedge mirror may be controlled in the vertical direction by tilting the arrangement of the wedge mirrors 35 and 36. This increases the degree of freedom in the arrangement of the optical system leading to the detector and the arrangement of the damper, so that the shape and configuration of the entire spectroscopic unit can be easily customized to meet various needs.

  In the above embodiment, one diffraction grating is arranged in the optical path, but two or more diffraction gratings may be arranged as appropriate. Thereby, the spectral efficiency can be further improved.

  Moreover, although the spectroscopic unit of the present invention described through the above embodiments is suitable for use in a weather observation lidar system, it can be used in various technical fields that utilize light.

It is the schematic which shows the basic composition of a weather observation lidar system. It is a figure for demonstrating the structure of a spectroscopy unit. It is a figure for demonstrating the detail of a diffraction grating. It is a figure for demonstrating the detail of arrangement | positioning of a wedge mirror part. It is a figure for demonstrating in detail the space | interval between wedge mirrors. It is a figure explaining the other structural example of a spectroscopy unit. It is a figure explaining in detail the arrangement | positioning state of the wedge mirror part in the spectroscopy unit shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transmission unit 2 ... Transmission unit 3 ... Spectroscopic unit 4 ... Analog / digital device 5 ... Control / processing unit 6 ... Optical fiber 11 ... Laser apparatus 12 ... Seeder 14 ... Beam expander 16 ... Computer 17 ... Display 18 ... Keyboard 19 ... Printer 31 ... Lens 32 ... Diffraction grating 33 ... Lens 34 ... Wedge mirror part 35, 36 ... Wedge mirror 35a, 36a ... Edge surface 35b, 36b ... Upper surface 37, 40, 43, 46 ... Lens 38, 39, 44, 45 ... Interference filter 41, 47 ... Detector 42 ... Damper 100 ... Weather observation lidar system

Claims (2)

A diffraction grating that generates diffracted light based on the target light;
Two wedge mirrors provided so that a gap is provided between them, and the optical path of the diffracted light passes through the gap;
A first interference filter disposed on an optical path of light passing through the gap between the two wedge mirrors;
A second interference filter disposed on an optical path of reflected light generated by at least one of the two wedge mirrors;
A spectroscopic unit. A transmission unit that generates pulsed laser light and launches it toward the atmosphere to be observed;
A receiving unit that receives reflected light from the atmosphere of the laser light emitted from the transmitting unit as observation target light; and
A spectroscopic unit that splits the observation target light received by the receiving unit to generate a plurality of signal lights, and converts the plurality of signal lights into electrical signals, respectively;
A control / processing unit that controls operations of the transmission unit, the reception unit, and the spectroscopic unit, and that performs signal processing based on the electrical signal output from the spectroscopic unit;
Including
A meteorological observation lidar system using the spectroscopic unit according to claim 1 as the spectroscopic unit.

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