JP2010271275A - Laser image measurement device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small laser image measurement device for measuring three and two-dimensional images of an object at high speed, high resolution and low cost. <P>SOLUTION: The laser image measurement device includes an oscillator 1 for generating a CW (continuous wave) modulation signal; a laser device 2 for generating a laser beam, a modulator 3 for modulating the intensity of a laser beam based on a modulation signal; a laser beam scanning optical system 4 for scanning and radiating the laser beam and generating a scanning angle; a receiving optical system 5 for condensing the reflected light from the object; a light receiver 6 that has an aperture capable of receiving the reflected light of many points of the object in a laser scanning range and converts the reflected light into an electrical signal; a phase detection device 7 for detecting the phase difference between the phase of the modulation signal and the phase of the electric signal of the reflected light obtained by the light receiver 6, a distance arithmetic device 8 for calculating the distance from the phase difference obtained by the phase detection device 7 to the object; and an image processor 9 for generating two and three-dimensional images, based on the scanning angle and the distance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image measuring apparatus using a laser. In particular, by using a single-element light receiver having a wide-field aperture capable of receiving the reflected light of multiple points in the laser scanning range, only the transmitted laser light is scanned using a small scanning optical system. By doing so, data is acquired at high speed. Furthermore, distance measurement is performed with high accuracy by applying a distance measurement method using a CW (Continuous Wave) modulation method. The present invention relates to a laser image measuring apparatus having both of the above.

  The laser distance measurement method for deriving the distance from the difference between the laser light oscillation time and the reflected light receiving time uses a pulse laser as the light source, and the pulse light time for deriving the distance from the time difference between the transmitted pulse light and the received pulse light CW modulation that uses CW laser light as the light source and modulates the intensity of the laser light with a single-frequency CW signal and derives the distance from the phase difference between the modulated signal during transmission and the electrical signal during reception There is a law.

  As a device for acquiring a three-dimensional shape of an object based on these laser distance measurement methods, a configuration is known in which both transmission and reception are two-dimensionally scanned with the transmission / reception axis being coaxial (see, for example, Patent Document 1). In this method, the distance at each point is measured, and a three-dimensional image is acquired from the distance measurement value and the scanned angle.

  In addition, as a measuring device that measures the shape of an object at high speed based on these laser distance measurement methods, a fan-shaped laser beam is scanned only in one axial direction, and a light receiving element is measured by a light receiver in a one-dimensional array. And a device for receiving and measuring a laser beam by spreading the laser beam over the entire field of view without scanning the beam, and receiving a light by a light receiving element of a two-dimensional array (for example, see Patent Document 2). .

  Further, there has been proposed a laser distance measuring device configured to scan only laser light and measure with a one-dimensional array of light receivers (see, for example, Patent Document 3).

Japanese Patent No. 2523633 Japanese Patent Laid-Open No. 10-38536 JP 2004-157044 A

  However, the prior art has the following problems. In general, in order to increase the measurement accuracy, it is necessary to increase the signal-to-noise ratio (reception S / N ratio) of the received signal. For this purpose, it is necessary to increase the reception aperture diameter and receive a large amount of reflected light. Since the conventional apparatus described in Patent Document 1 is configured to perform two-dimensional scanning for both transmission and reception, it is necessary to use a scanning optical system having a large aperture diameter. However, if a scanning optical system having a large aperture diameter is used, Inertia increases and scanning speed decreases.

  The conventional apparatus described in Patent Document 2 irradiates the entire field of view of the light receiver with laser light, and the light reception power of the single light receiver element is proportional to the irradiation power in the field of view of the single light receiver element. This means that a laser beam having a power larger than the number of light receiving elements is required as compared with the measurement apparatus of the method of Patent Document 1 that simply scans the transmission laser beam. Therefore, the laser device size, power consumption, cost, and the like are increased.

  The conventional apparatus described in Patent Document 3 is an apparatus that scans only a laser beam and receives an image with a one-dimensional array detector to acquire an image. In this apparatus, the resolution and field of view of an image are determined by performance such as the pixel size and size of the array detector. When performing measurement with a wide field of view and high resolution, a high-performance array detector with a small pixel size and a large number of elements is required, and the number of amplifiers in the subsequent stage increases, which increases costs. There are concerns.

  The present invention has been made to solve the above-described problems, and is capable of measuring a three-dimensional image of an object or a cross section of a two-dimensional image at high speed with a small size, low cost, and high resolution. An object is to obtain a laser image measuring device.

  A laser image measurement apparatus according to the present invention includes an oscillator that generates a reference continuous wave modulation signal, a laser apparatus that generates laser light, and a modulator that modulates the intensity of the laser light based on the modulation signal. A laser beam scanning optical system that scans and irradiates laser light intensity-modulated by the modulator, generates a scanning angle, a receiving optical system that collects reflected light from the object, and an object in the laser scanning range A single-element light receiver having a diameter capable of receiving reflected light from multiple points of an object, and converting the reflected light collected by the receiving optical system into an electrical signal; and the phase of the modulation signal and the light receiver A phase detector that detects a phase difference from the phase of the electrical signal detected in Step 1, a distance calculator that calculates a distance from the phase difference obtained by the phase detector to the object, and the scanning angle and distance 2-dimensional image or three-dimensional image from those and an image processing apparatus for generating.

  According to the laser image measurement device of the present invention, a wide reception field of view can be realized by increasing the aperture of the light receiver.

  Also, by using a light receiver with a wide field of view that can receive the reflected light of multiple points of the object in the laser scanning range, it is possible to scan only the laser light at high speed using a small transmission optical system. And a three-dimensional image can be acquired at high speed.

  Furthermore, since there is no need to scan the receiving optical system, the aperture diameter of the receiving optical system can be increased, and the reception SN ratio can be increased.

  Furthermore, since the scanning angle is measured by the angle sensor, the resolution of the acquired image depends on the scanning resolution and the resolution of the angle sensor, and the angular resolution can be varied depending on the measurement conditions. Therefore, it is possible to acquire a high-resolution image with a single-element light receiver.

  Here, generally, when the aperture of the photoreceiver is large, the capacitor capacity inside the photoreceiver becomes large, so that the frequency response characteristic of the photodetector is degraded. In the laser distance measurement method of the pulsed light time measurement method that requires the response characteristics of a broadband photodetector, the reflected light cannot be detected because this photodetector does not respond to the pulse waveform. Therefore, it is difficult to apply to the laser image measurement device according to the present invention. However, in the laser distance measurement method of the CW modulation method using intensity-modulated laser light, the modulation frequency to which the light receiver responds can be used, so that reflected light can be detected and distance measurement can be performed. it can.

  As described above, the laser image measurement device according to the present invention can measure a three-dimensional image or a two-dimensional image of a countermeasure object at high speed and at high speed.

It is a block diagram which shows the structure of the laser image measuring device which concerns on Embodiment 1 of this invention. It is a figure which shows the laser irradiation spot in the laser image measuring device which concerns on Embodiment 1 of this invention, and the reflected light condensing spot on a light receiver. It is a figure which shows the laser irradiation spot at the time of one-dimensional scanning in the laser image measuring device which concerns on Embodiment 1 of this invention, and the reflected light condensing spot on a light receiver. It is a block diagram which shows the structure of the phase detection apparatus of the laser image measuring device which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows the structure of the photoelectric conversion circuit of the laser image measuring device which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the frequency of the photoelectric conversion circuit of the laser image measuring device which concerns on Embodiment 1 of this invention, and noise. It is a figure which shows the example at the time of applying the laser image measuring device which concerns on Embodiment 1 of this invention to a vehicle detection system. It is a figure which shows the example at the time of applying the laser image measuring device which concerns on Embodiment 1 of this invention to a gate monitoring apparatus. It is a block diagram which shows the structure of the laser image measuring device which concerns on Embodiment 2 of this invention. It is a figure which shows the laser irradiation spot in the laser image measuring device which concerns on Embodiment 2 of this invention, and the reflected light condensing spot on a light receiver. It is a block diagram which shows the structure of the laser image measuring device which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the phase detection apparatus of the laser image measuring device which concerns on Embodiment 3 of this invention. It is a figure which shows the phase difference measured with a modulation signal in the laser image measuring device which concerns on Embodiment 3 of this invention.

  Hereinafter, preferred embodiments of a laser image measurement device of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
A laser image measurement apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a laser image measurement apparatus according to Embodiment 1 of the present invention. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

  In FIG. 1, a laser image measuring apparatus according to Embodiment 1 of the present invention includes an oscillator 1 that generates a reference modulation signal, a laser apparatus 2 that generates laser light, and the intensity of the laser light based on the modulation signal. A modulator 3 that performs modulation, a laser light scanning optical system 4 that functions as an angle sensor that scans the laser light and generates an electrical signal corresponding to the scanning angle, and a reflected light from the object is condensed to be described later. A receiving optical system 5 that leads to a receiving light receiver, a light receiving device 6 that converts reflected light into an electric signal, and a phase detector 7 that detects the phase difference between the phase of the modulation signal and the phase of the electric signal detected by the light receiving device 6. A distance calculation device 8 for deriving a distance from the phase difference obtained by the phase detector 7 and an image processing device 9 for generating a two-dimensional image or a three-dimensional image from the angle data and the distance data. .

  In addition, the combination of the receiving optical system 5 and the light receiver 6 can receive reflected light from multiple points in the laser beam scanning range. The distance calculation device 8 may have a function of deriving the intensity by deriving the amplitude of the modulated light received from the in-phase detection signal and the quadrature detection signal obtained by the phase detection device 7.

  FIG. 4 is a block diagram showing the configuration of the phase detector of the laser image measurement device according to Embodiment 1 of the present invention.

  In FIG. 4, the phase detector 7 includes an amplifier 71 that amplifies the electric signal obtained by the light receiver 6, a 0 ° distributor 72 that branches the amplified electric signal in phase, and a modulation signal generated by the oscillator 1. To the modulation signal generated from the oscillator 1, the 90 ° distributor 73 that branches so that the phase is orthogonal to the in-phase, the mixer 74 that mixes the modulated signal and the amplified electric signal of the light receiver 6, the mixer 75, and the oscillator 1. A filter 76 that transmits only the signal of the band based on it and a filter 77 are provided.

  Next, the operation of the laser image measurement device according to the first embodiment will be described with reference to the drawings.

  FIG. 2 is a diagram showing a laser irradiation spot and a reflected light condensing spot on the light receiver in the laser image measurement apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing a laser irradiation spot and a reflected light condensing spot on a light receiver when one-dimensional scanning is performed in the laser image measurement device according to Embodiment 1 of the present invention.

  Based on the modulation signal generated by the oscillator 1, the laser light generated from the laser device 2 is intensity-modulated by the modulator 3, and the laser light scanning optical system 4 scans the laser light 101 in an elevation angle and an azimuth angle.

  The reflected light from the object is collected by the receiving optical system 5 having the receiving field of view 102, converted into an electric signal by the light receiver 6, and output to the phase detector 7.

  As shown in FIG. 2, the light receiver 6 can receive reflected light from multiple points of objects in the laser scanning range. In FIG. 2, a laser irradiation spot 103 and a reflected light condensing spot 104 on the light receiver 6 are shown.

  As shown in FIG. 3, it is possible to use a long light receiver 6 that receives the reflected light of a multipoint object in the laser scanning range only on the long side, and further, by the laser light scanning optical system 4. Only one dimension may be scanned.

  As shown in FIG. 4, the phase detector 7 amplifies the electric signal obtained by the light receiver 6 by an amplifier 71 and then branches it by a 0 ° distributor 72. On the other hand, the modulation signal generated by the oscillator 1 is branched by a 90 ° distributor 73 so that the phase is orthogonal to the in-phase, mixed with the amplified electrical signal, and orthogonal to the in-phase detection signal 105 through the filters 76 and 77. A detection signal 106 is generated.

  The distance calculation device 8 detects the phase difference between the modulation signal at the time of transmission and the phase of the electrical signal obtained by the light receiver 6 at the time of reception from the obtained in-phase detection signal 105 and quadrature detection signal 106, and the detected phase difference The distance in the line-of-sight direction of the object is derived from

  Specifically, if the high speed is c, the phase difference is ΔΦ, and the modulation frequency is f, the distance L is derived by the following equation (1).

  L = (c · ΔΦ) / (4 · π · f) (1)

  Thereafter, the image processing device 9 generates a two-dimensional image or a three-dimensional image using the angle data obtained by the laser beam scanning optical system 4 and the distance data obtained by the distance calculation device 8.

  The laser image measuring apparatus according to the present invention can realize a wide field of view while maintaining the receiving aperture by increasing the aperture of the light receiver 6, and widen the laser scanning range that can receive the reflected light of multiple points of the object. The scanning of the receiving optical system 5 can be made unnecessary. Further, by using the light receiver 6 having a diameter capable of receiving the reflected light of multiple points of the object in the laser scanning range, the small laser light scanning optical system 4 corresponding to the beam diameter of the laser light is used. Only laser light can be scanned. By using the small scanning optical system 4, the scanning optical system 4 can operate with a small driving current, and can scan the laser beam at high speed. Therefore, the acquired image can be updated at a high speed. Furthermore, since there is no need to scan the reception optical system 5, the aperture diameter of the reception optical system 5 can be increased, and the reception SN ratio can be increased.

  In addition, by increasing the aperture of the light receiver, the laser scanning range in which the reflected light of the multipoint object can be received can be widened, and a wide range of images can be acquired at high speed. Here, when the aperture of the light receiver 6 is increased, the capacity of the capacitor inside the light receiver is increased, so that the frequency response characteristic is generally lowered and the noise level is increased. Specifically, when the aperture of the light receiver 6 is 0.4 mm as in the photodiode S5973 made by Hamamatsu Photonics, the capacitor capacity inside the light receiver is 1.6 pF, the bandwidth is about 1000 MHz, and the dark current indicating the noise level. Is 0.001 nA. On the other hand, when the aperture of the light receiver 6 is 14 mm as in the Hamamatsu photodiode S6801-01, the capacitor capacity is 40 pF, the bandwidth is reduced to 15 MHz, and the dark current is increased to 0.5 nA.

  Here, in the laser distance measurement method of the pulsed light time measurement method, a light receiver 6 having a wide frequency response characteristic is required so as to respond to the pulse waveform. Therefore, the light receiver 6 having a large aperture as in the present embodiment. Thus, it is difficult to apply to a laser image measurement apparatus that receives reflected light of multiple points in a laser scanning range.

  For example, when the reception SN ratio is 45 dB and a distance accuracy of 1 cm is required, it is necessary to use a pulse laser with a pulse width of about 3.7 ns in the pulsed light time measurement method. In order for the light receiver 6 to respond to this pulse width, a light receiver having a frequency response of 270 MHz is simply required. That is, when applied to a laser image measurement device that receives reflected light of multiple points of objects in the laser scanning range with the large-diameter light receiver 6 as in this embodiment, the photodetector does not respond to the pulse waveform. The pulsed light cannot be detected, making it difficult to detect the distance.

  On the other hand, in the laser distance measurement method of the CW modulation method, since the modulation frequency to which the light receiver 6 responds can be used, reflected light can be detected with a sufficient reception S / N ratio, and the distance can be measured.

  For example, when the reception SN ratio is 45 dB and the distance accuracy is 1 cm, the modulation frequency may be 9.5 MHz. In this case, the frequency of the modulated signal is 9.5 MHz, which is lower than the bandwidth of 15 MHz of the optical receiver having the aperture of 14 mm described above, so that it is possible to receive with a sufficient reception S / N ratio. In other words, by combining a laser image measuring device that receives reflected light of a multipoint object in a laser scanning range with a large-diameter light receiver 6 as in the present embodiment, and a laser distance measuring method of CW modulation method, High-speed distance measurement can be performed with high-speed scanning. When this modulation frequency is used, the phase difference becomes 2π at a distance of 15.8 m as shown in the equation (1), and the same phase difference is detected every period of 15.8 m.

  FIG. 5 shows an example of a photoelectric conversion circuit that converts an optical signal incident on the photodetector 6 into an electric signal when a laser distance measurement method using a single frequency CW modulation method is used. This photoelectric conversion circuit obtains an output voltage V by negative feedback amplification of the electrical signal obtained by the light receiver 6 by a feedback resistor 66 and a transimpedance amplifier 65. Here, when the light receiver 6 is represented by an equivalent circuit 6A, it can be constituted by a current source 61 inside the light receiver, a resistor 62 inside the light receiver, and a capacitor capacity 63 inside the light receiver. By adding the coil capacitance 64 to this circuit, the noise component due to the capacitor capacitance 63 can be reduced at the resonance frequency of the capacitor capacitance 63 and the coil capacitance 64.

  As a specific example, FIG. 6 shows a noise characteristic N1 when there is no coil capacitor 64 and a noise characteristic N2 when a coil capacitor 64 is added, as a characteristic example of noise level with respect to frequency. As described above, when the coil capacitance 64 is added, noise is reduced at the resonance frequency of the capacitor capacitance 63 and the coil capacitance 64. Therefore, by adjusting the resonance frequency to the modulation frequency fm, measurement can be performed under a low noise level condition, and a high reception S / N ratio can be obtained. Note that this method can be applied only to the laser distance measurement method based on the single frequency CW modulation method.

  Further, in the laser image measuring apparatus that receives the reflected light of a multipoint object in the laser scanning range with the single-element light receiver 6 as in this embodiment, the laser light scanning optical system 4 sets the scanning angle of the laser light. Obtainable. That is, the resolution of the acquired image depends on the scanning resolution, and a high-resolution image can be acquired by the single-element light receiver 6.

  As described above, when using a wide-angle reception field of view and high-speed transmission scan method for high-speed image acquisition, low-noise and high-sensitivity measurement can be performed for the first time by applying the CW modulation method using a single frequency. .

  FIG. 7 is a diagram illustrating an example in which the laser image measurement device according to Embodiment 1 of the present invention is applied to a vehicle detection system. By using the large-diameter light receiver 6 that receives the reflected light of the multipoint object in the laser scanning range as in this embodiment, only the laser light can be scanned at high speed with a small scanning optical system. . Therefore, the shape of the vehicle moving at high speed can be imaged with high resolution, and can be accurately measured.

  In addition, since the laser image measuring device according to the present invention can obtain a high SN ratio by increasing the aperture diameter of the receiving optical system 5, the distance at an object having a low reflectance such as a black vehicle, for example. Measurement is also possible, and various vehicle shapes can be measured. In addition, since the small laser beam scanning optical system 4 can scan only the laser beam at high speed to perform imaging, the shape of the vehicle moving at high speed can be accurately measured.

  When the laser image measuring device is one-dimensional scanning, the moving speed of the vehicle is measured at the same time, and another one-axis scanning is also performed by moving the vehicle. Here, even if the number of laser image measurement devices is not one, two or more laser image measurement devices may be used for measurement from various angles.

  FIG. 8 is a diagram illustrating an example in which the laser image measurement device according to the first embodiment of the present invention is applied to a gate monitoring device.

  Since the laser image measuring device according to the present invention can derive the phase accuracy with high accuracy by increasing the reception S / N ratio and the modulation frequency, the distance can be measured with high resolution and high accuracy, A thin string can be detected.

  As described above, the laser image measurement device according to the first embodiment can measure the three-dimensional image or the two-dimensional image of the countermeasure object at high speed and with high resolution.

Embodiment 2. FIG.
A laser image measurement apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS.

  In the laser image measurement device according to the second embodiment, the light reception sensitivity of the light receiver 6 of the laser image measurement device according to the first embodiment described above varies depending on the position on the light receiving surface, or the light collection spot position of the reflected light. The purpose of this is to reduce the decrease in the received signal-to-noise ratio due to the case where the frequency changes depending on the laser beam scanning angle.

  FIG. 9 is a block diagram showing a configuration of a laser image measurement apparatus according to Embodiment 2 of the present invention.

  In FIG. 9, a laser image measuring apparatus according to Embodiment 2 of the present invention includes an oscillator 1 that generates a reference modulation signal, a laser apparatus 2 that generates laser light, and the intensity of the laser light based on the modulation signal. A modulator 3 that performs modulation, a laser light scanning optical system 4 that functions as an angle sensor that scans the laser light and generates an electrical signal corresponding to the scanning angle, and a reflected light from the object is condensed to be described later. A receiving optical system 5 that leads to a receiving light receiver, a light receiving device 6 that converts reflected light into an electric signal, and a phase detector 7 that detects the phase difference between the phase of the modulation signal and the phase of the electric signal detected by the light receiving device 6. A distance calculation device 8 for deriving a distance from the phase difference obtained by the phase detector 7 and an image processing device 9 for generating a two-dimensional image or a three-dimensional image from the angle data and the distance data. .

  Further, the laser image measuring apparatus according to the second embodiment of the present invention uses the beam scanning angle angle data acquired from the laser beam scanning optical system 4 to obtain parameters relating to the light receiver 6, such as the bias voltage of the light receiver 6 and the light reception. A light receiver characteristic correction device 10 for controlling the irradiation angle and position of the surface is provided.

  Next, the operation of the laser image measurement apparatus according to the second embodiment will be described with reference to the drawings.

  FIG. 10 is a diagram showing a laser irradiation spot and a reflected light condensing spot on the light receiver in the laser image measurement apparatus according to Embodiment 2 of the present invention.

  Similar to the first embodiment, the laser light generated from the laser device 2 is intensity-modulated by the modulator 3 based on the modulation signal generated by the oscillator 1, and the laser light 101 is scanned by the laser light scanning optical system 4. Are scanned in elevation and azimuth.

  After the reflected light from the object is collected by the receiving optical system 5 having the receiving field of view 102, it is converted into an electric signal by the light receiver 6 and output to the phase detector 7.

  The light receiver 6 can receive the reflected light of multiple objects in the laser scanning range, such as the laser irradiation spot 103 and the focused spot 104 on the light receiver 6 in FIG. At this time, when the reception S / N ratio changes with respect to the position of the focused spot 104, that is, when the reception S / N ratio changes with respect to the scanning angle of the laser beam, the light receiver characteristic correction device 10 A control signal for correcting the change is sent, and the light receiver 6 corrects the change.

  For example, when the position of the condensing spot 104 deviates with respect to the laser beam scanning angle, the condensing diameter on the light receiving surface changes, and if the condensing diameter becomes larger than the light receiving surface, the reception SN ratio decreases. This tends to appear when the deflection angle of the laser beam scanning optical system 4 is large, and the position of the focused spot 104 comes closer to the light receiving surface. Therefore, as shown in FIG. 10, the position of the focused spot 104 is measured in advance with respect to the beam scanning angle, and the angle of the light receiver 6 is controlled with respect to the laser beam scanning angle.

  The phase detector 7 amplifies the electric signal obtained by the light receiver 6 by the amplifier 71 and then branches by the 0 ° distributor 72. On the other hand, the modulation signal generated by the oscillator 1 is branched by a 90 ° distributor 73 so that the phase is orthogonal to the in-phase, mixed with the amplified electrical signal, and orthogonal to the in-phase detection signal 105 through the filters 76 and 77. A detection signal 106 is generated.

  The distance calculation device 8 derives the phase of the reflected light from the obtained in-phase detection signal 105 and the quadrature detection signal 106, and derives the distance in the line-of-sight direction of the object from the difference from the phase at the laser emission end.

  Thereafter, the image processing device 9 generates a two-dimensional image or a three-dimensional image using the angle data obtained by the laser beam scanning optical system 4 and the distance data obtained by the distance calculation device 8.

  As in the laser image measurement device according to the present embodiment, the light receiver 6 is controlled by the light receiver characteristic correction device 10, so that the position of the focused spot 104 is deviated with respect to the laser beam scanning angle and is collected from the light receiving surface. When the light diameter is increased and the reception SN ratio is reduced, the decrease in the reception SN ratio can be reduced.

  In FIG. 10, a control signal is sent to the light receiver 6, and the angle of the light receiver 6 is controlled to improve the reception SN ratio reduction with respect to the position of the focused spot 104. However, the light receiver 6 is orthogonal to the optical axis. It may be configured to improve the reception SN ratio by moving in the two-axis direction. When the light receiving sensitivity changes on the light receiving surface, the output of the light receiver characteristic correction device 10 is sent to the amplifier 71, and the amplification degree of the amplifier 71 is controlled to make the light receiving sensitivity constant, or the light receiving function has an amplification function. In the case of the optical device 6, a configuration for controlling the amplification degree of the optical receiver 6 may be used. Furthermore, the control signal of the light receiver characteristic correction device 10 may be sent to the image processing device 9 and corrected by signal processing.

  Further, as in the first embodiment, a long light receiver 6 that receives reflected light of a multipoint object in the laser scanning range only on the long side of FIG. 3 may be used. Only one dimension may be scanned by the optical scanning optical system 4.

Embodiment 3 FIG.
A laser image measurement apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS.

  Regarding the distance measurement of the laser image measurement device according to the first embodiment, the same phase is detected for each distance corresponding to one period of the modulation frequency generated from the oscillator 1, and the measurable absolute distance is limited. Therefore, the laser image measurement device according to the third embodiment aims to overcome the above-described problems.

  FIG. 11 is a block diagram showing a configuration of a laser image measurement apparatus according to Embodiment 3 of the present invention.

  In FIG. 11, a laser image measurement device according to Embodiment 3 of the present invention is based on oscillators 1A and 1B that generate a reference modulation signal, laser devices 2A and 2B that generate laser light, and a modulation signal. Modulators 3A and 3B that modulate the intensity of laser light, laser light scanning optical system 4 that functions as an angle sensor that scans the laser light and generates an electrical signal corresponding to the scanning angle, and reflected light from the object A receiving optical system 5 that collects the light and guides it to a light receiver described later, a light receiver 6 that converts the reflected light into an electric signal, and a phase difference between the phase of the modulation signal and the phase of the electric signal detected by the light receiver 6. A phase detection device 7A for detecting, a distance calculation device 8 for deriving a distance from the phase difference obtained by the phase detection device 7A, and an image processing device 9 for generating a two-dimensional image or a three-dimensional image from the angle data and the distance data. It is provided.

  The oscillator 1A and the oscillator 1B generate a reference modulation signal 205 and a modulation signal 206, respectively. The laser device 2A and the laser device 2B generate laser beams at different wavelengths. Also, the modulator 3A and the modulator 3B apply intensity modulation to the laser light based on the modulation signal 205 and the modulation signal 206, respectively. The laser beam scanning optical system 4 has a function of an angle sensor that combines two laser beams and scans the laser beams to generate an electrical signal corresponding to the scanning angle.

  FIG. 12 is a block diagram showing the configuration of the phase detector of the laser image measurement device according to Embodiment 3 of the present invention.

  In FIG. 12, a phase detector 7A includes an amplifier 71 that amplifies the electrical signal obtained by the light receiver 6, a 0 ° distributor 72 that branches the amplified electrical signal in phase, a 0 ° distributor 78, 90 ° distributors 73A and 73B for branching the modulated signal generated by the 0 ° distributor 79 and the oscillators 1A and 1B so that the phases thereof are orthogonal to the in-phase, and the modulated signals and the amplified electrical signals of the light receiver 6 Mixers 74A and 74B to be mixed, mixers 75A and 75B, filters 76A and 76B that transmit only signals in a band based on modulation signals generated from the oscillators 1A and 1B, and filters 77A and 77B are provided.

  The 0 ° distributors 72, 78, and 79 branch the electric signal amplified by the amplifier 71 in the same phase. The 90 ° distributor 73A and the 90 ° distributor 73B branch the modulated signal 205 and the modulated signal 206 so that the phases thereof are orthogonal to the in-phase. The mixers 74A and 74B and the mixers 75A and 75B mix the modulated signal 205, the modulated signal 206, and the amplified electrical signal of the light receiver 6, respectively. Filters 76A and 76B and filters 77A and 77B transmit only signals in bands based on modulated signal 205 and modulated signal 206, respectively.

  Next, the operation of the laser image measurement apparatus according to the third embodiment will be described with reference to the drawings.

  FIG. 13 is a diagram showing a phase difference measured with a modulation signal in the laser image measurement apparatus according to Embodiment 3 of the present invention.

  Based on the modulation signal 205 and the modulation signal 206 generated by the oscillator 1A and the oscillator 1B, the laser light 2a and the laser light b generated from the laser device 2A and the laser device 2B are modulated by the modulator 3A and the modulator 3B, After the multiplexing, the laser beam scanning optical system 4 scans the laser beam 101 in an elevation angle and an azimuth angle.

  After the light reflected from the object is collected by the receiving optical system 5, it is converted into an electric signal by the light receiver 6, and outputted to the phase detector 7A.

  In the phase detector 7A, based on the modulation signal 205 and the modulation signal 206, the in-phase detection signal 201 for the modulation signal 205 and the quadrature detection signal 202 for the modulation signal 205, the in-phase detection signal 203 for the modulation signal 206, and the quadrature detection for the modulation signal 206 are detected. A signal 204 is generated.

  The light receiver 6 can receive the reflected light of multi-point objects in the laser scanning range, such as the laser irradiation spot 103 and the focused spot 104 on the light receiver 6 in FIG.

  The phase detector 7A amplifies the electric signal obtained by the light receiver 6 by the amplifier 71, and then branches the signal into four by the 0 ° distributors 72, 78, and 79. On the other hand, the modulated signal 205 and the modulated signal 206 generated by the oscillator 1A and the oscillator 1B are branched by the 90 ° distributor 73A and the 90 ° distributor 73B so that the phases are orthogonal to the in-phase, and are mixed with the amplified electrical signals. Then, the in-phase detection signal 201 for the modulation signal 205, the quadrature detection signal 202 for the modulation signal 205, the in-phase detection signal 203 for the modulation signal 206, and the quadrature detection signal 204 for the modulation signal 206 are passed through the filters 76A and 76B and the filters 77A and 77B. Generate.

  The distance calculation device 8 obtains the phase of the reflected light from the in-phase detection signal 201 and the quadrature detection signal 202 for the modulation signal 205, the in-phase detection signal 203 for the modulation signal 206 and the quadrature detection signal 204 for the modulation signal 206. And the distance in the line-of-sight direction of the object is derived from the difference from the phase at the laser emission end.

  FIG. 13 shows examples of the modulation signal 205 and the modulation signal 206 at this time, and the reflection signal 207 and the reflection signal 208 from the object. Further, a phase difference 209 measured by the modulation signal 205 and a phase difference 210 measured by the modulation signal 206 are shown. When the distance of the object corresponds to within one period of the modulation signal 205, the distance can be derived from the phase difference as it is as in the first embodiment. On the other hand, when the distance is equal to or longer than the distance corresponding to one period of the modulation signal 205, the phase rotates 360 degrees, and the obtained phase difference 209 is not accurately derived. Here, by using the modulation signal 206 having a long wavelength, a rough distance is derived from the phase difference 210 with respect to the reflected signal 208, and the absolute distance is derived with high accuracy by correcting the number of phase rotations in the modulation signal 205. be able to.

  Thereafter, the image processing device 9 generates a two-dimensional image or a three-dimensional image using the angle data obtained by the laser beam scanning optical system 4 and the distance data obtained by the distance calculation device 8.

  As with the laser image measurement device according to the present embodiment, even if the distance to the object is equal to or longer than the distance corresponding to one period of the modulation signal 205 with a short wavelength, it is derived from the modulation signal 206 with a long wavelength. By using the phase difference 210, the rotational speed of the phase derived from the modulation signal 205 having a short wavelength can be corrected, and the absolute distance can be derived with high accuracy.

  In the third embodiment, an example using two types of oscillators, laser devices, and modulators is shown, but a configuration using two or more types may be used.

  Further, as in the first embodiment, a long light receiver 6 that receives reflected light of a multipoint object in the laser scanning range only on the long side of FIG. 3 may be used. Only one dimension may be scanned by the optical scanning optical system 4.

  Moreover, it is good also as a structure which reduces the fall of receiving S / N ratio by the light receiver characteristic correction apparatus 10 similarly to said Embodiment 2. FIG.

  Furthermore, as in the first embodiment, the second embodiment and the third embodiment can be applied to a vehicle detection system and a gate monitoring device.

  1, 1A, 1B oscillator, 2, 2A, 2B laser device, 3, 3A, 3B modulator, 4 laser light scanning optical system, 5 reception optical system, 6 light receiver, 7, 7A phase detection device, 8 distance calculation device , 9 Image processing device, 10 Receiver characteristic correction device.

Claims (5)

An oscillator that generates a reference continuous wave modulation signal;
A laser device for generating laser light;
A modulator that modulates the intensity of the laser light based on the modulation signal;
A laser beam scanning optical system that scans and irradiates laser light intensity-modulated by the modulator and generates a scanning angle;
A receiving optical system for collecting the reflected light from the object;
A single-element light receiver having a diameter capable of receiving reflected light of multiple points of an object in a laser scanning range, and converting the reflected light collected by the receiving optical system into an electrical signal;
A phase detector for detecting a phase difference between the phase of the modulation signal and the phase of the electrical signal detected by the light receiver;
A distance calculation device for calculating a distance from the phase difference obtained by the phase detection device to the object;
A laser image measurement device comprising: an image processing device that generates a two-dimensional image or a three-dimensional image from the scanning angle and distance. A first oscillator for generating a reference continuous wave first modulated signal;
A first laser device for generating a first laser beam;
A first modulator that modulates the intensity of the first laser beam based on the first modulation signal;
A second oscillator for generating a reference continuous wave second modulation signal having a wavelength longer than that of the first modulation signal;
A second laser device that generates a second laser beam having a wavelength different from that of the first laser beam;
A second modulator that modulates the intensity of the second laser beam based on the second modulation signal;
A laser beam scanning optical system that combines the laser beams intensity-modulated by the first and second modulators, scans and irradiates the combined laser beams, and generates a scanning angle;
A receiving optical system for collecting the reflected light from the object;
A single-element light receiver having an aperture capable of receiving reflected light of a multipoint object in a laser scanning range, and converting the reflected light collected by the receiving optical system into an electrical signal;
The first phase difference between the phase of the first modulation signal and the phase of the first electric signal detected by the light receiver is detected, and the phase of the second modulation signal and the first phase detected by the light receiver are detected. A phase detector for detecting a second phase difference from the phase of the electrical signal of 2;
A distance calculation device for calculating a distance from the first and second phase differences obtained by the phase detection device to the object;
A laser image measurement device comprising: an image processing device that generates a two-dimensional image or a three-dimensional image from the scanning angle and distance. The laser image measurement device according to claim 1, further comprising a light receiver characteristic correction device that corrects the characteristics of the light receiver based on the scanning angle. The laser image measurement device according to claim 1, wherein the laser image measurement device is applied to a vehicle detection system. The laser image measurement device according to claim 1, wherein the laser image measurement device is applied to a gate monitoring device.

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