JP2017083272A - Substance detection device and substance detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substance detection device with which it is possible to improve the accuracy of detecting a substance in a detection area.SOLUTION: The substance detection device comprises: a transmitter for wavelength-modulating a first invisible light and emitting it into a substance detection area; a receiver for receiving a second invisible light that is the first invisible light reflected by a substance in the detection area; a detector for detecting a substance on the basis of the wavelength characteristic of the second invisible light; an actuator for changing the emission direction of the first invisible light and the reception direction of the second invisible light; and a controller for changing a modulation frequency that is the frequency with which the first invisible light is wavelength-modulated, and a detection frequency that corresponds to the modulation frequency for detecting a substance by the detector.SELECTED DRAWING: Figure 10

Description

  The present disclosure relates to a substance detection device and a substance detection method.

  Conventionally, a gas detection device that performs gas detection on a predetermined point is known (see Patent Document 1). In this gas detection apparatus, laser light emitted from an LD (Laser Diode) module is split into measurement light and reference light by a half mirror. The measurement light is used for normal gas detection. The reference light is received by the wavelength processing light receiver after passing through the gas cell. The wavelength processing control unit performs wavelength confirmation processing and wavelength calibration processing of the LD module based on the detection signal corresponding to the received reference light.

JP 2008-232920 A

  The gas detection device described in Patent Literature 1 assumes gas detection at an arbitrary point, and does not assume detection of a substance present in an arbitrary area (space). If an arbitrary area is set as a gas detection range, the substance detection accuracy may be lowered.

  This indication is made in view of the above-mentioned conventional situation, and provides a substance detection device and a substance detection method which can improve detection accuracy of a substance in a detection field.

  The substance detection device according to the present disclosure is a transmitter that wavelength-modulates and emits first invisible light into a substance detection area, and light in which the first invisible light is reflected by the substance in the detection area. A receiver that receives the second invisible light, a detector that detects the substance based on the wavelength characteristics of the second invisible light, and the emission direction of the first invisible light and the second in the detection region A controller that changes an actuator that changes the light receiving direction of invisible light, a modulation frequency that is a frequency modulation frequency of the first invisible light, and a detection frequency that corresponds to the modulation frequency for detecting a substance by the detector. And comprising.

  According to the present disclosure, it is possible to improve the detection accuracy of a substance in the detection region.

The schematic diagram explaining the outline | summary of the detection camera containing the invisible light sensor in 1st Embodiment. Schematic diagram showing an example of the internal configuration of the detection camera Schematic diagram showing an example of scanning the detection area by the sensor scan unit Block diagram showing a configuration example of a detection camera Block diagram showing a configuration example of the light receiving processing unit Schematic diagram for explaining the input and output signals of laser light when the wavelength of the laser light emitted from the laser diode is optimal for the absorption spectrum of the specific substance Graph showing an example of time change of output signal of laser diode and output signal of photodiode The figure for demonstrating an example of the spot detection in a substance detection operation | movement Schematic diagram for explaining an example of area detection when there is no background change in the substance detection operation Schematic diagram for explaining an example of area detection when there is a background change in the substance detection operation Schematic diagram for explaining a determination example of the substance detection result Schematic diagram for explaining in detail examples of substance detection results Flow chart showing an example of a substance detection operation by an invisible light sensor Flowchart showing an example of a substance detection operation by an invisible light sensor (continuation of FIG. 13) Schematic diagram showing an example of modulation pattern Schematic diagram showing another example of modulation pattern

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the claimed subject matter.

(Background to obtaining one form of the present disclosure)
In the conventional gas detection apparatus, the LD module emits laser light that is wavelength-modulated around an arbitrary wavelength, and the photodiode receives the laser light reflected by the detection region. At this time, in the state where the reflectance excluding the detection target in the detection region is uniform, when a substance to be detected is detected, a frequency twice the frequency of wavelength modulation by the LD module is output from the photodiode. When the substance to be detected is not detected, a frequency twice the frequency of the wavelength modulation does not appear in the output signal of the photodiode. The state where the reflectance is uniform is a state where the background in the detection region is one color, for example.

  On the other hand, in the state where the reflectance excluding the detection target in the detection region is non-uniform, the output signal varies with respect to the input signal of the photodiode even if there is no detection target. For example, when the background color is a stripe state of two colors and the frequency of the background reflectance approximates to twice the frequency of the input signal, even if there is no detection target, the frequency of the input signal is twice that of the input signal. If an output signal appears and there is an object to be detected, it may be erroneously detected. In this case, the substance detection accuracy decreases.

  Hereinafter, a substance detection apparatus and a substance detection method capable of improving the substance detection accuracy in the detection region will be described.

(First embodiment)
[Configuration]
FIG. 1 is a schematic diagram illustrating an outline of a detection camera 1 including an invisible light sensor NVSS in the embodiment. The detection camera 1 is configured to include a visible light camera VSC and a non-visible light sensor NVSS.

  The visible light camera VSC is a person HM existing in a predetermined detection space K using reflected light RM for visible light having a predetermined wavelength (for example, 0.4 to 0.7 μm), for example, in the same manner as an existing surveillance camera. Or an object (not shown). Hereinafter, output image data captured by the visible light camera VSC is referred to as “visible light camera image data”.

  Therefore, the detection camera 1 includes both configurations of a non-visible light sensor NVSS that detects non-visible light and a visible light camera VSC that obtains visible light camera image data by imaging. The detection camera 1 including at least the invisible light sensor NVSS is an example of a substance detection device.

  The invisible light sensor NVSS projects laser light LS, which is invisible light (for example, infrared light) having a predetermined wavelength, to the same detection space K as the visible light camera VSC by surface irradiation using optical scanning. To do. The projected laser beam LS is light including a wavelength in an absorption wavelength band of a substance to be detected (also referred to as a specific substance).

  The invisible light sensor NVSS determines whether or not a specific substance is detected in the detection space K by using the laser light RV that is reflected by the object to be detected (for example, a gas GS such as methane gas as the specific substance).

  The specific substance for determining the presence or absence of detection by the non-visible light sensor NVSS is, for example, a substance that is difficult to discriminate with visible light camera image data from the visible light camera VSC, and may be a liquid or a solid in addition to a gas (gas). Here, a case where the substance to be detected is a gas GS is illustrated.

  In addition, the detection camera 1 includes output image data (hereinafter, “substance position image data”) including a determination result of whether or not a specific substance is detected by the invisible light sensor NVSS in the visible light camera image data captured by the visible light camera VSC. Or display data obtained by synthesizing information (substance name, etc.) on the substance position image data.

  The output destination of the display data from the detection camera 1 is an external connection device connected to the detection camera 1 via a network (not shown), for example, the camera server CS or the monitor 150 shown in FIG. A substance detection system is configured including the detection camera 1 and the monitor 150. The network may be a wired network (for example, an intranet or the Internet), or a wireless network (for example, a wireless LAN (Local Area Network)).

  FIG. 2 is a schematic diagram showing the internal configuration of the detection camera 1. FIG. 2 shows the internal configuration of the detection camera 1 when viewed from the top of FIG. 1 (downward in the z-axis direction).

  The detection camera 1 has, for example, a box-shaped housing 1z. An opening 1w for the invisible light sensor NVSS is formed on the front surface of the housing 1z. Note that transparent glass or resin may be fitted in the opening 1w for waterproofing and dustproofing. Further, the imaging lens V31 (see FIG. 4) of the visible light camera VSC is exposed on the front surface of the housing 1z.

  A sensor scan unit 5 is provided inside the housing 1z. The sensor scan unit 5 includes a pan head 10 and a pan / tilt unit 15 (see FIG. 4). The pan / tilt head 10 is turnable in a pan direction (a direction along the xy plane in the drawing) represented by an arrow P in FIG. 2 and a tilt direction (a z-axis direction in the drawing) represented by an arrow T in the drawing. The pan / tilt unit 15 includes a motor mechanism (not shown) that drives the camera platform 10.

  On the camera platform 10, a laser diode LD, a collimating lens PLZ, a photodiode PD, and a condenser lens CLZ are mounted. The pan / tilt unit 15 scans the detection area SAR two-dimensionally (horizontal scanning and vertical scanning) using the laser light LS emitted from the laser diode LD by turning the pan head 10 in the pan direction and the tilt direction. It is possible.

  The laser light LS emitted from the laser diode LD passes through the collimating lens PLZ and becomes parallel light, and is emitted toward the detection space K. The laser light RV reflected by the gas GS in the detection space K enters through the opening 1w formed in the housing 1z of the detection camera 1, is collected by the condenser lens CLZ, and is received by the photodiode PD. The

  From the absorption spectrum (absorption characteristic) of the laser beam RV received by the photodiode PD, the presence / absence of the gas GS, which is a substance to be detected, present in the detection space K is determined. The detection area SAR is set by the shape of the opening 1w formed in the housing 1z, for example. The detection region SAR corresponds to a range (scan angle of view) in which the laser light LS emitted from the laser diode LD can be scanned in the detection space K.

  Here, the laser diode LD is easily affected by temperature, and the wavelength of the laser light LS emitted from the laser diode LD is shifted by a slight temperature change. For this reason, the invisible light sensor NVSS keeps the temperature of the laser light LS emitted from the laser diode LD constant so that the wavelength of the laser light LS (center wavelength in wavelength modulation) does not change during the gas detection operation. In addition, temperature control (control for temperature adjustment) is performed.

  In order to control the temperature of the laser light LS emitted from the laser diode LD, a diffusion plate DEF is disposed outside the detection region SAR close to the opening 1w of the housing 1z. A reference cell CEL is disposed between the diffusion plate DEF and the laser diode LD. In the reference cell CEL, a gas having the same component as that of the specific substance (here, methane gas) is sealed.

  In the temperature control, when the laser light LS emitted from the laser diode LD passes through the reference cell CEL and is diffused by the diffusion plate DEF, a part of the diffused light passes through the condensing lens CLZ to detect the substance. Light is received by the photodiode PD. Further, since the laser light LS is diffused by the diffusion plate DEF, the light amount of the laser light RV received by the photodiode PD is reduced and falls within the allowable light receiving amount range of the photodiode PD.

  FIG. 3 is a schematic diagram illustrating a scanning example of the detection area SAR by the sensor scan unit 5. When the camera platform 10 of the sensor scan unit 5 rotates, the laser light LS emitted from the laser diode LD mounted on the camera platform 10 is moved in the pan direction (horizontal direction) in the scan field angle (detection area SAR). Scan in the tilt direction (vertical direction). In FIG. 3, the diffusion plate DEF is disposed at a horizontal position beyond the scanning end position EP before one scanning with the laser light LS ends and the laser light LS returns to the initial position HP.

  In the temperature control, the laser light LS emitted from the laser diode LD is diffused by the diffusion plate DEF, passes through the reference cell CEL in which the gas that is the substance to be detected is sealed, and the condenser lens CLZ for substance detection And collected by a photodiode PD for substance detection.

  FIG. 4 is a block diagram showing the configuration of the detection camera 1.

  As described above, the detection camera 1 includes the invisible light sensor NVSS and the visible light camera VSC. The invisible light sensor NVSS includes a control unit 11, a projection unit PJ, and a light reception processing unit SA.

  The controller 11 is configured using, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or a DSP (Digital Signal Processor). The control unit 11 includes, for example, signal processing for overall control of operation of each unit of the invisible light sensor NVSS, data input / output processing with other units, data calculation processing, and data storage processing. I do. Further, the control unit 11 sets a detection threshold M for detecting a specific substance that is a detection target of the invisible light sensor NVSS in the detection processing unit 27.

  Further, the control unit 11 sends a timing signal for AD conversion to the detection processing unit 27. The control unit 11 sends a light source emission signal for modulating the laser light LS emitted from the laser diode LD to the laser diode LD.

  The control unit 11 includes a wavelength detection temperature adjustment control unit 12, inputs a temperature adjustment state signal described later from the detection processing unit 27, generates a temperature adjustment control signal based on the temperature adjustment state signal, and performs temperature control. A signal is sent to the laser diode LD. The temperature control signal is a signal for controlling the temperature of the laser light LS emitted from the laser diode LD, and is a signal for instructing heat absorption or heat generation to a Peltier element (not shown) included in the laser diode LD. . The laser diode LD varies the center wavelength of the emitted laser light LS according to a change in temperature.

  Further, the control unit 11 switches the frequency modulation frequency (modulation frequency) of the laser light LS. The control unit 11 switches the frequency (detection frequency) for detecting the laser beam RV in which the laser beam LS is reflected by the specific substance in accordance with the switching of the modulation frequency. The detection frequency is twice the modulation frequency. In addition, the control unit 11 refers to setting information held in the memory 13 (for example, information such as at which timing the modulation frequency or the detection frequency is switched), and switches the modulation frequency or the modulation frequency. The modulation frequency information is included in the light source emission signal and sent to the laser diode LD. Information on the detection frequency is sent to the detection processing unit 27.

  The projection unit PJ includes a laser diode LD, a collimator lens PLZ, and a pan / tilt unit 15.

The laser diode LD emits a laser beam LS having a wavelength adjusted so that the wavelength of the laser beam LS matches the peak of the absorption wavelength band of the gas GS that is the detection target substance. Here, methane gas (CH ₄ ) is given as an example of the gas that is the substance to be detected.

  Various methods are used for wavelength adjustment. For example, the control unit 11 modulates the wavelength of the laser light LS emitted from the laser diode LD by modulating the drive current of the laser diode LD as a semiconductor diode. The drive current is an input signal of the semiconductor diode, and the frequency of the drive current becomes the modulation frequency. Further, the Peltier element Pt provided in the laser diode LD absorbs heat or generates heat in accordance with the temperature control signal from the control unit 11 and varies the temperature of the laser diode LD, thereby adjusting the center wavelength of the laser light LS.

  The collimating lens PLZ converts the laser light LS emitted from the laser diode LD into parallel light.

  The pan / tilt unit 15 rotates the pan / tilt head 10 on which the laser diode LD, the collimating lens PLZ, the condenser lens CLZ, and the photodiode PD are mounted in the pan direction and the tilt direction. The pan / tilt unit 15 uses the laser light LS emitted from the laser diode LD to scan two-dimensionally within the scanning range including the detection area SAR.

  FIG. 5 is a block diagram showing a configuration of the light reception processing unit SA.

  The light reception processing unit SA includes a condenser lens CLZ, a photodiode PD, a signal processing unit 26, a detection processing unit 27, and a display processing unit 28. The signal processing unit 26 includes an I / V conversion circuit 261, an amplification circuit 262, and a filter processing circuit 263. The detection processing unit 27 includes an AD conversion circuit 271, a temperature control processing unit 272, and a substance detection processing unit 273.

  Each function of the temperature control processing unit 272, the substance detection processing unit 273, and the display processing unit 28 of the detection processing unit 27 is realized by the processor 20 executing a program held in the memory 13.

  The condensing lens CLZ condenses the laser light RV emitted from the laser diode LD and reflected by the specific substance in the detection region SAR, and causes the photodiode PD to receive the light. The photodiode PD generates a charge corresponding to the light amount of the received laser beam RV and outputs it as a current signal.

  The I / V conversion circuit 261 converts the current signal output from the photodiode PD into a voltage signal. The amplifier circuit 262 amplifies the voltage signal output from the I / V conversion circuit 261. The filter processing circuit 263 performs filter processing on the signal amplified by the amplification circuit 262 and outputs the signal to the AD conversion circuit 271 in the detection processing unit 27 as a signal used for substance detection.

  The AD conversion circuit 271 in the detection processing unit 27 converts the signal input from the signal processing unit 26 into a digital signal when detecting a specific substance or controlling the temperature of the laser diode LD.

  The temperature control processing unit 272 generates a signal indicating the temperature control state (temperature control state signal) based on the value converted into a digital value by the AD conversion circuit 271 in the temperature control operation, and outputs the signal to the control unit 11. . This temperature control state signal is a signal indicating the magnitude (signal level) of a signal having a frequency (2f) twice that of the signal (frequency 1f) of the wavelength-modulated laser beam LS emitted from the laser diode LD. It is.

  It is assumed that the temperature of the laser diode LD is not changed and the modulation wavelength width of the laser light LS emitted from the laser diode LD is not shifted from the absorption wavelength band of the specific substance. In this case, the temperature control state signal has a signal magnitude (signal level) having a frequency (2f) that is twice the frequency 1f.

  On the other hand, it is assumed that the temperature of the laser diode LD changes and the modulation wavelength width of the laser light LS emitted from the laser diode LD is shifted from the absorption wavelength band of the specific substance. In this case, the temperature control state signal becomes a signal whose frequency fluctuates, and the magnitude (signal level) of the frequency (2f) which is twice the frequency 1f and which is obtained based on the signal from the photodiode PD2 becomes small. .

  The substance detection processing unit 273 detects the specific substance based on the value output from the signal processing unit 26 in the light reception processing unit SA in the substance detection operation and converted into a digital value by the AD conversion circuit 271, and detects the specific substance. A signal representing the detection result is output to the display processing unit 28.

  Here, the substance detection processing unit 273 is a signal of the wavelength-modulated laser light LS emitted from the laser diode LD based on the value converted into the digital value by the AD conversion circuit 271 similarly to the temperature control state signal. A signal indicating the magnitude (signal level) of a signal having a frequency (2f) twice that of (frequency 1f) is obtained. The substance detection processing unit 273 generates a signal representing the detection result of the specific substance based on the signal indicating the magnitude (signal level) of the signal having the double frequency (2f).

  The display processing unit 28 generates substance position image data indicating the two-dimensional position of the specific substance in the detection region SAR from the invisible light sensor NVSS. The substance position image data includes image data representing a specific substance and two-dimensional position information (for example, pan angle and tilt angle of the camera platform 10) in the detection area SAR. The display processing unit 28 outputs the substance position image data to the display control unit 37 of the visible light camera VSC.

  In this manner, the information on the specific substance obtained by the detection processing unit 27 is combined with the visible light image data in the detection area SAR and displayed and output. Therefore, the non-visible light sensor NVSS can clearly show to the user where the specific substance is present in the detection region SAR.

  In this embodiment, instead of transmitting the substance position image data to the display control unit 37 in the visible light camera VSC, the display processing unit 28 transmits the substance position image data to, for example, a monitor 150, a camera server CS, and a communication terminal described later. Also good.

  As shown in FIG. 4, the visible light camera VSC includes an imaging lens V31, an image sensor V33, a signal processing unit V35, a display control unit 37, and an output unit 38. Each function of the signal processing unit V35 and the display control unit 37 is realized by the processor V20 executing a program held in the memory 39.

  The imaging lens V31 uses the range including the detection area SAR by the invisible light sensor NVSS as the field angle range, collects incident light (reflected light RM) from the outside, and forms an image on the imaging surface of the image sensor V33.

  The image sensor V33 has a spectral sensitivity peak with respect to the wavelength of visible light (for example, 0.4 μm to 0.7 μm). The image sensor V33 converts an optical image formed on the imaging surface into an electric signal. The output of the image sensor V33 is input to the signal processing unit V35 as an electrical signal.

  The signal processing unit V35 generates visible light image data defined by, for example, RGB (Red Green Blue) or YUV (luminance / color difference) using an electrical signal that is an output of the image sensor V33. Thereby, visible light image data imaged by the visible light camera VSC is formed. The signal processing unit V35 outputs visible light image data to the display control unit 37.

  For example, when a specific substance is detected at a predetermined position in the visible light image data, the display control unit 37 displays the visible light image data output from the signal processing unit V35 and the substance position output from the display processing unit 28. The display data is generated by combining the image data. This display data is an example of information regarding a specific substance.

  The output unit 38 outputs the display data to an external device (for example, the camera server CS and the monitor 150).

  The camera server CS transmits display data output from the display control unit 37 to a communication terminal or one or more externally connected devices (not shown), and display data on a display screen of the communication terminal or one or more externally connected devices. Prompt display.

  The monitor 150 displays the display data output from the display control unit 37.

[Absorption characteristics of specific substances]
FIG. 6 is a schematic diagram for explaining an input signal and an output signal of the photodiode PD when the wavelength of the laser light LS emitted from the laser diode LD is optimal with respect to the absorption spectrum of the specific substance.

In FIG. 6, methane gas (CH ₄ ) is taken as an example as a gas that is a substance to be detected. In FIG. 6, the vertical axis represents the light reception voltage (unit is a normalized value) of the photodiode PD, and the horizontal axis represents the wavelength (nm) of the laser light RV received by the photodiode PD. The lower the light reception voltage, the higher the absorption rate of the laser light LS by the specific substance. In addition, the absorption characteristic of a substance is decided according to the substance.

  In FIG. 6, the absorption spectrum of the specific substance has a wavelength band centered on 1653.67 nm. On the other hand, the laser light emitted from the laser diode LD is modulated with a modulation width of 0.05 nm with a center wavelength of 1653.67 nm as shown in the wavelength modulation range WAR0.

  As described above, the laser light LS is emitted from the laser diode LD, and the laser light RV (input signal) reflected by the specific substance in the detection region SAR is 2 with respect to the signal of the laser light RV by the photodiode PD. It is detected as a signal (output signal) having a double frequency. In this case, a sine wave signal having a constant frequency is output.

  The control unit 11 switches the modulation frequency to one of the first modulation frequency (f1) and the second modulation frequency (f2), and emits laser light. Note that there are three or more modulation frequencies, and the frequency may be switched to any one of them.

  Further, the control unit 11 switches the detection frequency to one of the first detection frequency (2 × f1) and the second detection frequency (2 × f2) in accordance with the switching of the modulation frequency. Note that the number of detection frequencies is three or more, and may be switched to any one of them.

  That is, in the photodiode PD, a first output signal (2 × f1) having a frequency twice that of the wavelength-modulated first input signal (1 × f1) is obtained. Further, a second output signal (2 × f2) having a frequency twice that of the wavelength-modulated second input signal (1 × f2) is obtained.

  FIG. 7 is a graph showing an example of temporal changes in the input signal and output signal of the photodiode PD. In FIG. 7, “LD output” indicates a signal of the output of the laser diode LD (that is, the laser light LS), and the vertical axis indicates the wavelength. “PD output” indicates a signal output from the photodiode PD (the same applies to FIGS. 8 to 10 below).

  The signal received by the photodiode PD (input to the photodiode PD) has a frequency twice that of the modulation frequency of the laser light LS emitted from the laser diode LD when an object to be detected exists. .

  In addition, the frequency of the signal output from the photodiode PD, that is, the detection frequency is twice the modulation frequency. Therefore, when the modulation frequency of the laser light LS is the first modulation frequency f1, the first detection frequency for detecting the laser light RV wavelength-modulated at the first modulation frequency f1 is the first modulation frequency. The frequency is twice that of f1 (2 × f1). In addition, when the modulation frequency of the laser light LS is the second modulation frequency f2, the second detection frequency for detecting the laser light RV wavelength-modulated at the second modulation frequency f2 is the second modulation frequency. The frequency is twice that of f2 (2 × f2).

  For example, the second modulation frequency f2 is set to 5/3 times the first modulation frequency f1. This 5/3 times is an example, and other multiples may be used. For example, the first modulation frequency f1 is set to 1.5 Hz, and the second modulation frequency f2 is set to 2.5 Hz. Note that the second modulation frequency f2 may be set to be a multiple of the first modulation frequency f1.

The laser light LS emitted from the laser diode LD is reflected by the substance in the detection region SAR and received by the photodiode PD. In this case, the signal level of the input signal to the photodiode PD is 0 when there is no gas (as an example, methane gas: CH ₄ ) in the detection region SAR. For this reason, the signal level of the output signal of the laser diode LD is also zero.

  When gas is present (exists) in the detection region SAR, the first detection frequency is the frequency (f1 × 2) with respect to the first modulation frequency f1, and a signal including a signal of this frequency is obtained. Similarly, with respect to the second modulation frequency f2, the second detection frequency is a frequency (f2 × 2), and a signal including a signal of this frequency is obtained. Note that although two modulation frequencies are used as an example, three or more modulation frequencies may be used.

[Operation etc.]
Next, the operation of the detection camera 1 will be described.
First, three kinds of substance detection operations will be described.

  FIG. 8 is a schematic diagram for explaining spot detection in the substance detection operation. In the spot detection, the invisible light sensor NVSS detects a specific substance by irradiating one point in the detection area SAR with the laser light LS.

  When spot detection is performed, the non-visible light sensor NVSS obtains a signal sg1 having no frequency (2f) twice the modulation frequency as an output signal of the photodiode PD if there is no specific substance (for example, methane gas). On the other hand, when the specific substance is present, the invisible light sensor NVSS obtains a signal sg2 having a frequency (2f) twice the modulation frequency as an output signal of the photodiode PD.

  FIG. 9 is a diagram for explaining area detection when there is no background change in the substance detection operation. In area detection, the invisible light sensor NVSS scans the detection region SAR in the horizontal direction and the vertical direction, and irradiates the laser light LS to detect a specific substance.

  When the area detection is performed, the non-visible light sensor NVSS obtains a signal sg3 having no frequency (2f) twice the modulation frequency as an output signal of the photodiode PD if there is no specific substance. On the other hand, when a specific substance is present, the invisible light sensor NVSS obtains a signal sg4 having a frequency (2f) twice the modulation frequency as an output signal of the photodiode PD.

  FIG. 10 is a schematic diagram for explaining area detection when there is a background change in the substance detection operation. An example of a background change is a white and black stripe pattern painted on a wall surface. White has high light reflectance, and black has low light reflectance.

  When the non-visible light sensor NVSS scans the laser beam in the direction orthogonal to the stripe pattern of FIG. 10, even if there is no specific substance, the signal sg10 that changes as the output signal of the photodiode PD changes with the background change. Get. Therefore, the non-visible light sensor NVSS obtains a signal that may be erroneously detected as the presence of a specific substance when the background change rate is close to the first detection frequency (2 × f1). Become. Here, the background change rate is the same as the reflectance of the laser beam, and can be said to be the background reflectance.

  In addition, when a substance is detected using the second detection frequency (2 × f2), when the background change rate approximates the first detection frequency (2 × f1), the background change rate is the second detection frequency (2 × f2). It does not approximate f2). Therefore, the invisible light sensor NVSS obtains a signal sg11 having no second detection frequency (2 × f2) as an output signal of the photodiode PD.

  Thus, when the specific substance does not exist, at least one of the detection frequencies 2 × f1, 2 × f2 does not approximate the background change rate. Therefore, the non-visible light sensor NVSS obtains different substance detection results. Therefore, when the results detected using the two modulation frequencies f1 and f2 are different, the non-visible light sensor NCSS can determine that one result is a false detection and that the specific substance does not exist.

  On the other hand, when the specific substance is present, when the background change rate approximates the first detection frequency (2 × f1), the signal of the first detection frequency (2 × f1) and the signal indicating the background change rate are added. Is done. Therefore, the invisible light sensor NVSS obtains a signal sg12 having a first detection frequency (2 × f1) and a large signal level as an output signal of the photodiode PD.

  In addition, when a substance is detected using the second detection frequency (2 × f2), when the background change rate approximates the first detection frequency (2 × f1), the background change rate is the second detection frequency (2 × f2). It does not approximate f2). Therefore, the signal of the second detection frequency (2 × f2) is distinguished from the signal indicating the background change rate, and the invisible light sensor NVSS outputs the second detection frequency (2 × f2) as an output signal of the photodiode PD. ) And a signal sg13 having a normal signal level is obtained.

  Therefore, when a specific substance is present, the substance detection results detected using the two modulation frequencies f1 and f2 are the same.

  As described above, the non-visible light sensor NVSS uses the two modulation frequencies f1 and f2 when a specific substance is present, so that one of the detection frequencies 1 × 2f and 2 × 2f approximates the background change rate. Both output signals having a frequency (1 × 2f, 2 × 2f) that is twice the modulation frequency. Therefore, the non-visible light sensor NVSS can determine that the specific substance is present without outputting a signal that is erroneously detected that the specific substance does not exist.

  FIG. 11 is a schematic diagram for explaining determination of a substance detection result.

  As will be described later, the control unit 11 of the invisible light sensor NVSS switches the modulation frequency and the detection frequency according to a predetermined condition (for example, for each frame, for each line, or for each unit region). FIG. 11 illustrates that the modulation frequency and the detection frequency are switched for each frame.

  A frame corresponds to the entire detection area SAR to be scanned. A line is the same line (line) to be scanned. The unit area is a minimum area to be scanned in the detection area SAR. When scanning for one frame is completed in the detection area SAR, the process proceeds to scanning of the next frame in the same detection area SAR.

  For example, the laser diode LD emits the laser light LS at the first modulation frequency f1 in the previous frame (first frame). The laser diode LD emits the laser light LS at the second modulation frequency f2 in the current frame (second frame).

  In FIG. 11, numbers 1, 2,..., N assigned to the lines (L1, L2,..., Lm) in the detection region SAR represent the irradiation positions of the laser light LS. The detection processing unit 27 compares the detection result of the specific substance with the laser light with the modulation frequency f1 in the previous frame and the detection result of the specific substance with the laser light with the modulation frequency f2 in the current frame at each irradiation position.

  The detection processing unit 27 determines that a specific substance does not exist when a false detection occurs when the detection results of the two do not match. On the other hand, the detection processing unit 27 determines that there is no specific detection and the specific substance exists when the detection results of the two match.

  FIG. 12 is a schematic diagram for explaining the determination of the substance detection result in detail. FIG. 12 illustrates that the modulation frequency and the detection frequency are switched for each frame, as in FIG. 11.

  “Input data” shown in FIG. 12 is data of a detection result of a specific substance for one frame. This input data is stored in the memory 13 for comparison with the detection result of the specific substance for other frames. This input data includes, for example, information on the presence / absence of the specific substance and information on the signal level of the output signal of the photodiode PD acquired via the signal processing unit 26. The signal level information of the output signal included in the input data is also simply referred to as the input data signal level.

  The “output data” illustrated in FIG. 12 is a detection result output by the detection processing unit 27 as a result of comparison between the detection result of the specific substance for one frame and the detection result of the specific substance for another frame. The output data includes, for example, information on the presence / absence of a specific substance.

  The detection processing unit 27 compares a plurality of input data and outputs output data based on any of the input data.

  In FIG. 12, numbers 1, 2,..., 10 represent irradiation positions of the laser light LS. As described above, when the presence / absence of the specific substance included in the input data Da of the previous frame is equal to the presence / absence of the specific substance included in the input data Db of the current frame at the same irradiation position, the detection processing unit 27 performs false detection. It is determined that the specific substance is present or absent. The detection processing unit 27 outputs information on the presence / absence of a specific substance based on the input data Db of the current frame as output data.

  On the other hand, the presence / absence of the specific substance included in the input data Da of the previous frame is different from the presence / absence of the specific substance included in the input data Db of the current frame, and the signal level of the input data Da is lower than the signal level of the input data Db. And In this case, the detection processing unit 27 outputs, as output data, information on the presence / absence of the specific substance based on the input data Da having a low signal level.

  Further, the presence / absence of the specific substance included in the input data Da of the previous frame is different from the presence / absence of the specific substance included in the input data Db of the current frame, and the signal level of the input data Da is higher than the signal level of the input data Db. And In this case, the detection processing unit 27 outputs, as output data, information on the presence / absence of a specific substance based on the input data Db having a low signal level.

  That is, the detection processing unit 27 has a false detection when the presence / absence of the specific substance included in the input data Da of the previous frame is different from the presence / absence of the specific substance included in the input data Db of the current frame at the same irradiation position. It is determined that the specific substance does not exist. And the detection process part 27 outputs the information that a specific substance does not exist as output data based on the input data Da or Db with a small signal level.

  13 and 14 are flowcharts showing an example of the substance detection operation by the invisible light sensor NVSS.

  The controller 11 determines the modulation frequency of the laser light LS and performs initial setting of the light source emission signal (S1). In the initial setting, the modulation frequency is set to, for example, the first modulation frequency f1 (<f2). The set information (setting information) is stored in the memory 13.

  The projection unit PJ emits the laser light LS according to the set modulation frequency under the control of the control unit 11 (S2). The emitted laser beam LS is reflected by the substance in the detection region SAR, and the laser beam RV is incident on the photodiode PD. The photodiode PD outputs a signal based on the incident laser beam RV.

  The signal processing unit 26 receives and amplifies the signal from the photodiode PD (output signal of the photodiode PD) (S3).

  The detection processing unit 27 refers to the setting information held in the memory 13 and determines whether or not the modulation frequency is the first modulation frequency f1 (S4).

  When the modulation frequency is the first modulation frequency f1, the detection processing unit 27 performs the detection process of the specific substance using the first detection frequency (2 × f1) (S5), and detects the gas that is the specific substance. Whether or not there is is determined (S7). Here, the detection processing unit 27 extracts a signal having the first detection frequency (2 × f1) from the signals amplified by the signal processing unit 26, and determines the presence or absence of the specific substance. The presence or absence of the gas GS is determined, for example, based on whether or not the signal of the first detection frequency (2 × f1) is equal to or higher than the detection threshold M. The specific substance detection process is performed for each unit region.

  The detection processing unit 27 reads the detection result (corresponding to the input data Da shown in FIG. 12) of the specific substance in the previous frame in the detection area SAR from the memory 13 (S8). Further, the detection processing unit 27 writes the detection result of the specific substance in the current frame (corresponding to the input data Db shown in FIG. 12) in the memory 13 (S8). The specific substance detection result in the current frame held in the memory 13 is used for the next specific substance detection process together with the specific substance detection result in the next frame.

  The detection processing unit 27 determines whether or not the detection result (here, the presence or absence of a specific substance) related to the previous frame matches the detection result (here, the presence or absence of a specific substance) related to the current frame (S9).

  If the detection result related to the previous frame and the detection result related to the current frame match, the detection processing unit 27 adopts the detection result related to the current frame, ) Is sent to the display processing unit 28 (S10).

  On the other hand, when the detection result related to the previous frame and the detection result related to the current frame do not match, the detection processing unit 27 adopts the detection result related to the frame with the lower signal level of the output signal of the photodiode PD, The detection result (here, information on the presence or absence of a specific substance) related to the corresponding frame is sent to the display processing unit 28 (S11).

  That is, when detection result data relating to a frame with a low light reception level is output, the detection processing unit 27 uses data on which the specific substance has not been detected as correct detection result data, assuming that a false detection has occurred. .

  When the modulation frequency is the second modulation frequency f2 in S4, the detection processing unit 27 performs a specific substance detection process using the second detection frequency (2 × f2) (S6), and is a specific substance. The presence or absence of gas detection is determined (S7). Even when the second detection frequency (2 × f2) is used, the non-visible light sensor NVSS performs the processes of S8 to S11 as in the case of using the first detection frequency (1 × f1).

  The display processing unit 28 generates substance position image data based on the detection result of the specific substance from the detection processing unit 27, and outputs it to the display control unit 37 (S12). The substance position image data includes, for example, an image representing the position (direction) of the specific substance when the gas GS that is the specific substance exists. The display control unit 37 generates display data by superimposing the substance position image data on the imaging data captured by the visible light camera VSC, and outputs the display data to the camera server CS and the monitor 150 via the output unit 38.

  Subsequently, the control unit 11 determines whether or not it is the modulation frequency switching timing (S13). For example, the control unit 11 determines that it is the modulation frequency switching timing in the switching timing of the frame, the line, and the irradiation position (unit region).

  If it is not the switching timing, the pan / tilt unit 15 changes the scanning position (S17). In other words, the pan / tilt unit 15 drives the camera platform 10 and directs each device mounted on the camera platform 10 to the scanning position of the next laser beam LS. Each device includes a laser diode LD, a collimating lens PLZ, a photodiode PD, and a condenser lens CLZ.

  Then, the control unit 11 determines whether or not to continue the substance detection operation (S18). Whether or not to continue the substance detection operation is based on, for example, the setting information stored in the memory 13, the time, and the operation of turning on and off the detection camera 1 and the invisible light sensor NVSS.

  When continuing the substance detection operation, the non-visible light sensor NVSS proceeds to the process of S3. When the substance detection operation is not continued, the non-visible light sensor NVSS ends the processes of FIGS. 13 and 14.

  When it is the modulation frequency switching timing in S13, the control unit 11 refers to the memory 13 and determines whether or not the modulation frequency is set to the first modulation frequency f1 (S14).

  When the modulation frequency is set to the first modulation frequency f1, the control unit 11 sets the modulation frequency to the second modulation frequency f2, and stores this setting information in the memory 13 (S15). On the other hand, when the modulation frequency is set to the second modulation frequency f2, the control unit 11 sets the modulation frequency to the first modulation frequency f1, and stores this setting information in the memory 13 (S16). After the processes of S15 and S16, the invisible light sensor NVSS proceeds to the process of S17.

  13 and 14 exemplify that the modulation frequency can be set to one of the two frequencies. However, as described above, the modulation frequency may be set to any frequency from among three or more. . In this case, the modulation frequency after switching may be set according to a predetermined order or may be set in an arbitrary order.

[Details of modulation pattern]
As a modulation frequency switching method, a plurality of variations (modulation patterns) are assumed. 15 and 16 are schematic diagrams showing the modulation patterns PT0 to PT5. 15 and 16, L1, L2, L3,..., Lm indicate line numbers in the horizontal direction. The numbers 1, 2, 3,..., N represent the irradiation positions of the laser light LS in the detection area SAR. Information indicating which modulation pattern the control unit 11 sets to switch the modulation frequency is stored in the memory 13 in advance.

  Note that a plurality of variations (detection patterns) are also assumed for the detection frequency switching method. Since the detection pattern is set in the same manner corresponding to the modulation pattern, detailed description is omitted.

  The modulation pattern PT0 shows a case where the control unit 11 fixes the modulation frequency without switching the modulation frequency. In the modulation pattern PT0, the modulation frequency is fixed to the first modulation frequency f1 in any frame.

  In the modulation pattern PT1, a case where the control unit 11 alternately switches the modulation frequency in units of frames (one detection operation for the entire detection region SAR) is shown (sequential frame).

  In the first frame, the modulation frequency is the first modulation frequency f1. In the second frame, the modulation frequency is the second modulation frequency f2. In the third frame, the modulation frequency is again the first modulation frequency f1.

  The modulation pattern PT2 indicates a case where the control unit 11 alternately switches the modulation frequency for each line in the horizontal direction and changes the modulation frequency to be started for each frame (line sequential).

  In the first frame, the modulation frequency is set to the first modulation frequency f1 in the first line, and the modulation frequency is set to the second modulation frequency f2 in the second line. Thereafter, the modulation frequency is alternately set to the first modulation frequency f1 or the second modulation frequency f2 in line units.

  In the second frame, the modulation frequency is set to the second modulation frequency f2 in the first line, and the modulation frequency is set to the first modulation frequency f1 in the second line. Thereafter, the modulation frequency is alternately set to the first modulation frequency f1 or the second modulation frequency f2 in line units. The third and subsequent frames are a repetition of the first frame and the second frame.

  In the modulation pattern PT3, the control unit 11 switches the modulation frequency alternately for each irradiation position (unit region) (unit region sequential).

  In the first line of the first frame, the modulation frequency is set to the first modulation frequency f1 at the first irradiation position, and the modulation frequency is set to the first irradiation frequency adjacent to the first irradiation position. 2 modulation frequency f2. In the third and subsequent irradiation positions, the modulation frequency is alternately switched in the same manner as in the first irradiation position and the second irradiation position.

  In the second line of the first frame, the modulation frequency is set to the second modulation frequency f2 at the first irradiation position, and the modulation frequency is set to the first modulation frequency f1 at the second irradiation position. The In the third and subsequent irradiation positions, the modulation frequency is alternately switched in the same manner as in the first irradiation position and the second irradiation position. The third and subsequent lines are repetitions of the first and second lines.

  In the first line of the second frame, the modulation frequency is set to the second modulation frequency f2 at the first irradiation position, and the modulation frequency is set to the first modulation frequency f1 at the second irradiation position. The In the third and subsequent irradiation positions, the modulation frequency is alternately switched in the same manner as in the first irradiation position and the second irradiation position.

  In the second line of the second frame, the modulation frequency is set to the first modulation frequency f1 at the first irradiation position, and the modulation frequency is set to the second modulation frequency f2 at the second irradiation position. The In the third and subsequent irradiation positions, the modulation frequency is alternately switched in the same manner as in the first irradiation position and the second irradiation position. The third and subsequent lines are repetitions of the first and second lines.

  The third and subsequent frames are a repetition of the first frame and the second frame.

  In the modulation patterns PT0 to PT3, it is assumed that the control unit 11 irradiates the laser light LS with one modulation frequency to one irradiation position. In the modulation patterns PT4 and PT5, the control unit 11 divides one irradiation position, and irradiates each of the divided positions with the laser light LS at two different modulation frequencies.

  In the modulation pattern PT4, the control unit 11 irradiates laser light in the order of the first modulation frequency f1 and the second modulation frequency f2 at each irradiation position in all lines of all frames. That is, the control unit 11 sets the same phase without switching the modulation frequency for each frame in the same unit region.

  In the modulation pattern PT5, the control unit 11 switches the order of the modulation frequencies f1 and f2 at each irradiation position alternately for each frame. That is, at each irradiation position of the first frame, the laser light is irradiated in the order of the first modulation frequency f1 and the second modulation frequency f2, and at each irradiation position of the second frame, the second modulation frequency f2, Laser light is irradiated in the order of 1 modulation frequency f1. That is, the control unit 11 switches the modulation frequency for each frame and switches the phase alternately in the same unit region.

  In this way, the non-visible light sensor NVSS suppresses the influence of the background change rate even in a place where the background change in the detection region SAR is large by switching the modulation frequency in units of lines or irradiation positions, so that the specific substance It can be detected. Similarly, by detecting a substance in the same unit area using a plurality of detection frequencies, it is possible to detect a specific substance while suppressing the influence of the background change rate even in a place where the background change in the detection area SAR is large.

[Effects]
As described above, the detection camera 1 includes the laser diode LD, the photodiode PD, the detection processing unit 27, the pan / tilt unit 15, and the control unit 11. The laser diode LD wavelength-modulates and emits the laser beam LS into the substance detection region SAR. The photodiode PD receives the laser beam RV, which is the light reflected from the substance in the detection region SAR. The detection processing unit 27 detects a substance (for example, gas GS) based on the wavelength characteristic of the laser beam RV. The pan / tilt unit 15 changes the emission direction of the laser beam LS and the light reception direction of the laser beam RV in the detection region SAR. The control unit 11 changes the modulation frequency, which is the frequency modulation frequency of the laser light LS, and the detection frequency corresponding to the modulation frequency for detecting the substance by the detection processing unit 27.

  The laser diode LD is an example of a transmitter. The photodiode PD is an example of a receiver. The detection processing unit 27 is an example of a detector. The pan / tilt unit 15 is an example of an actuator. The control unit 11 is an example of a controller.

  As a result, the control unit 11 changes the modulation frequency and irradiates the laser diode LD with laser light. The detection processing unit 27 detects the specific substance based on the wavelength characteristic of the laser light RV using the detection frequency corresponding to the changed modulation frequency. Therefore, the detection camera 1 can improve the substance detection accuracy even when the background reflectance is not uniform. Moreover, when switching the modulation frequency and the detection frequency in time division, the detection camera 1 can change a specific substance (target) as a detection target in time division.

  Further, the laser diode LD may emit the laser light LS a plurality of times in the detection region SAR. The photodiode PD may receive the laser beam RV a plurality of times in the detection region SAR. The detection processing unit 27 may repeat the detection operation for detecting the gas GS as the specific substance a plurality of times in the detection region SAR. The control unit 11 changes the modulation frequency and the detection frequency for each detection operation in the entire detection region SAR (frame), for each detection operation in a line along a predetermined direction in the detection region SAR, or for each unit region in the detection region SAR. May be.

  Thereby, the detection camera 1 can switch a modulation frequency and a detection frequency by various methods, and can improve the detection accuracy of a substance. For example, even when the absorption characteristics in the wavelength modulation at one modulation frequency and the detection frequency are similar to the characteristics of the background change, the detection camera 1 has the absorption characteristics in the wavelength modulation at other modulation frequencies and detection frequencies. And background change characteristics can be set to be distinguishable.

  In addition, the detection processing unit 27 detects the substance using the first detection frequency (2 × f1) and the substance using the second detection frequency (2 × f2) in an arbitrary area in the detection area SAR. Detection may be repeated.

  Thereby, the detection camera 1 can acquire at least one substance detection result using a detection frequency different from the background reflectance in the same region at an arbitrary timing, and can improve the substance detection accuracy.

  Further, the detection processing unit 27 detects the substance using the first detection frequency (2 × f1) and the detection of the substance using the second detection frequency (2 × f2) in the same unit region. And may be performed by one detection operation.

  Thereby, the detection camera 1 can detect a substance using a plurality of detection frequencies within the same unit region, and can improve the substance detection accuracy.

  In addition, the detection processing unit 27 detects the detection result of the substance using the first detection frequency (2 × f1) and the detection result of the substance using the second detection frequency (2 × f2) in an arbitrary area in the detection area SAR. If the detection result is different, it may be determined that the specific substance does not exist in any region.

  Thereby, the detection camera 1 can suppress erroneous detection of a specific substance, and can improve the detection accuracy of the substance.

(Other embodiments)
As described above, the first embodiment has been described as an example of the technique in the present disclosure. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments in which changes, replacements, additions, omissions, and the like are performed.

  In the first embodiment, the laser light transmitted through the reference cell CEL is received by the substance detection photodiode PD and processed by the light reception processing unit SA. The adjustment unit may be provided in the housing. The temperature adjustment unit includes, for example, a condenser lens, a photodiode, an I / V conversion circuit, an amplification circuit, and a filter processing circuit. The temperature control unit controls the temperature of the laser light emitted from the laser diode LD based on the wavelength characteristic of the reflected light received by the temperature control photodiode. Thereby, the invisible light sensor NVSS can reduce the processing load of the light receiving processing unit SA. Further, the temperature control may be performed by another method.

  In the first embodiment, infrared light is used as invisible light, but ultraviolet light may be used depending on the absorption spectrum of the substance to be detected. Thereby, the detection camera 1 can expand the range of the detectable substance.

  In the first embodiment, the processor and the controller may be physically configured in any manner. Further, if a programmable processor or controller is used, the processing contents can be changed by changing the program, so that the degree of freedom in designing the processor and controller can be increased. The processor and the controller may be constituted by one semiconductor chip, or may be physically constituted by a plurality of semiconductor chips. When configured by a plurality of semiconductor chips, each control of the first embodiment may be realized by separate semiconductor chips. In this case, it can be considered that a plurality of semiconductor chips constitute one processor or controller. Further, the processor and the controller may be configured by a member (capacitor or the like) having a function different from that of the semiconductor chip. Further, one semiconductor chip may be configured so as to realize the functions of the processor and the controller and other functions.

  The present disclosure is useful for a substance detection apparatus and a substance detection method that can improve the detection accuracy of a substance in a detection region.

DESCRIPTION OF SYMBOLS 1 Detection camera 1w Opening part 1z Case 5 Sensor scan unit 10 Pan head 11 Control part 12 Wavelength detection temperature control part 13,39 Memory 15 Pan tilt unit 20, V20 Processor 26 Signal processing part 27 Detection processing part 28 Display processing part 261 I / V conversion circuit 262 Amplification circuit 263 Filter processing circuit 37 Display control unit 150 Monitor 271 AD conversion circuit 272 Temperature control processing unit 273 Substance detection processing unit CEL Reference cell CLZ Condensing lens CS Camera server EP Scan end position GS Gas HM Person HP Initial position K Detection space LS, RV Laser light LD Laser diode MR1 Reflector NVSS Invisible light sensor PD Photodiode PJ Projection part PLZ Collimating lens SA Light reception processing part SAR Detection area V31 Imaging lens V33 Image Sensor V35 Signal processing unit VSC Visible light camera WAR0 Wavelength modulation range

Claims (6)

A transmitter for wavelength-modulating and emitting the first invisible light into a substance detection region;
In the detection region, a receiver that receives the second invisible light that is the light reflected by the substance in the first invisible light;
A detector for detecting the substance based on a wavelength characteristic of the second invisible light;
An actuator that changes an emission direction of the first invisible light and a light receiving direction of the second invisible light in the detection region;
A controller that changes a modulation frequency, which is a frequency modulation frequency of the first invisible light, and a detection frequency corresponding to the modulation frequency for detecting the substance by the detector;
A substance detection apparatus comprising: The substance detection device according to claim 1,
The transmitter emits the first invisible light a plurality of times in the detection region;
The receiver receives the second invisible light a plurality of times in the detection region;
The detector repeats a detection operation for detecting the substance a plurality of times in the detection region,
The controller sets the modulation frequency and the detection frequency for each detection operation in the entire detection region, for each detection operation in a line along a predetermined direction in the detection region, or for each unit region in the detection region. Change the substance detection device. The substance detection device according to claim 2,
The detector repeatedly detects the substance using the first detection frequency and the substance detection using the second detection frequency in an arbitrary area of the detection area. . The substance detection device according to claim 3,
The detector performs detection of the substance using the first detection frequency and detection of the substance using the second detection frequency in the same unit region in the one detection operation. Substance detection device. The substance detection device according to claim 3,
The detector is configured to detect the arbitrary detection region when the detection result of the substance using the first detection frequency is different from the detection result of the substance using the second detection frequency in an arbitrary region in the detection region. A substance detection apparatus for determining that the substance does not exist in a region. In the detection region of the substance, change the emission direction of the first invisible light and the light reception direction of the second invisible light, which is the light reflected by the substance,
Changing a modulation frequency that is a frequency modulation frequency of the first invisible light and a detection frequency corresponding to the modulation frequency for detecting the substance;
Wavelength-modulating and emitting the first invisible light into the detection region;
In the detection region, the first invisible light is received as a second invisible light that is reflected by a substance,
A substance detection method for detecting the substance based on a wavelength characteristic of the second invisible light.

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