JP2007108122A - Laser measuring method, laser condition detection equipment, and laser condition detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide laser condition detection equipment capable of detecting highly reliably a condition using a self-coupling effect of a semiconductor laser element. <P>SOLUTION: This laser condition detection equipment for analyzing an irradiation beam superposed with an interference signal generated by the self-coupling effect in the semiconductor laser element to detect a condition up to a measuring object, using the semiconductor laser element for emitting a wavelength-modulated laser beam toward the measuring object, and for introducing the laser beam reflected by the measuring object, is provided, in particular, with a condition detecting photoreceiver provided to receive only the irradiation beam emitted from the laser element, and an object detecting photoreceiver provided to receive only the reflected beam by the object. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser measurement method, a laser state detection device, and a laser state detection system suitable for measuring and detecting the state of a measurement object using a self-coupling effect (also referred to as a self-mixing effect) in a laser element.

  One of optical state detection techniques uses a self-coupling effect of laser light (see, for example, Patent Documents 1 and 2). In this method, for example, as shown in FIG. 5, a laser element (hereinafter referred to as LD) 1 driven using a predetermined modulation signal is irradiated with a laser beam to a measurement object 2 and reflected by the measurement object 2 to be reflected by the above-described method. Irradiation light in which an interference signal generated by the self-coupling effect between the reflected light returning to the laser element 1 and the irradiation light is superimposed is received by a light receiver (hereinafter referred to as PD) 3 and the output thereof is subjected to frequency analysis. The state of the measurement object 2 is detected.

  That is, when the oscillation wavelength of the output light from the laser element 1 is continuously changed, the return light reflected by the detection target 2 and the output light of the laser element 1 interfere with each other, and the laser is used at a wavelength that satisfies the resonance condition. The amplification efficiency of the element 1 is slightly increased, and the amplification efficiency is slightly decreased at a wavelength satisfying the attenuation condition. As a result, the output of the light receiver 3 repeatedly increases and decreases. For example, if a semiconductor laser element of the type in which the oscillation wavelength of the laser light changes according to the applied current value is modulated using a triangular wave α whose current value changes over time as shown in FIG. The wavelength of the laser beam continuously increases with the continuous increase of the current value, and the wavelength of the laser beam continuously with the continuous decrease of the current value after the current value reaches the peak. To decrease.

In this way, while the wavelength of the laser light continuously increases and decreases, the resonance condition and the attenuation condition between the irradiation light and the return light (reflected light) are satisfied many times. As a result, a beat waveform (modulated light) β in which a minute interference component is superimposed on the triangular wave α is obtained from the light receiver 3. This interference component includes information such as the distance L between the laser element 1 and the detection target 2. Therefore, if this beat waveform β is analyzed, it is possible to detect the distance, speed, vibration, and the like from the frequency of the resonance component to the object 2. For example, as shown in FIG. 5, it is possible to detect the state of the measurement object by differentiating the beat waveform β and extracting the signal component superimposed on the triangular wave α and counting the signal component.
JP 10-246782 A JP-A-11-287859

  By the way, the interference component superimposed on the triangular wave α described above is a minute signal component. For this reason, when the above-described interference component cannot be detected from the output of the light receiver 3, there is a problem that it cannot be determined whether the cause is that the interference component is too weak or no interference itself occurs. is there. In other words, the interference component generated by the self-coupling effect in the laser element cannot be detected because it is weak, or there is no return light (reflected light) because there is no measurement object. There is a problem that it cannot be identified whether an effect (resonance / damping) has not occurred.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a laser measurement method and a laser state detection device capable of reliably performing state detection using the self-coupling effect of a laser element. There is to do.

  In order to achieve the above-described object, a laser measurement method according to the present invention irradiates a measurement target with wavelength-modulated laser light and introduces the laser beam reflected by the measurement target. When detecting the irradiation light on which the interference signal generated by the self-coupling effect in the laser element is superimposed to detect the state of the measurement object, the reflected light from the measurement object is used independently of the irradiation light. It is characterized by detecting the presence or absence of the measurement object by receiving light (claim 1).

  Incidentally, in the case of detecting a reflected light component of laser light emitted from the laser element toward the measurement object as reflected light by the measurement object that is detected independently of the irradiation light, the measurement object It is preferable that only the light is detected by blocking the reflected light by, and the light reflected by the measurement object is detected by blocking the light. Further, when detecting the reflected light component of the auxiliary light emitted from the light source different from the laser element toward the measurement object as reflected light by the measurement object to be detected independently of the irradiation light, It is desirable to detect only the reflected light by blocking the irradiation light.

In addition, a laser state detection device according to the present invention uses a semiconductor laser element that irradiates a measurement target with wavelength-modulated laser light and introduces the laser light reflected by the measurement target. Analyzing the irradiation light superimposed with the interference signal generated by the self-coupling effect in the element to detect the state of the measurement object,
In particular, it is provided with a state detection light receiver provided so as to be able to receive only the irradiation light from the laser element, and an object detection light receiver provided so as to be able to receive only the reflected light from the object. (Claim 4).

Preferably, when the laser element emits a laser beam to an object to be measured through an objective lens as described in claim 5,
<a> The irradiation light of the laser element can be directly received or a part of the irradiation light reflected by the objective lens can be received, and the reflected light from the measurement object can reach through the objective lens. While providing the above-mentioned state detection light receiver at a position,
<b> Detection of the object at a position where the reflected light from the measurement object reaches through the objective lens and the irradiation light of the laser element and the irradiation light reflected by the objective lens do not reach An optical receiver is provided.

  According to the laser state detection apparatus of the present invention, as described in claim 6, a state detection light receiver provided so as to be able to receive only the irradiation light of the laser element, and auxiliary light toward the measurement object. It is also possible to configure as a light source for irradiating and a light receiving device for detecting an object provided so as to be able to receive only the reflected light of the auxiliary light reflected from the object by blocking the irradiation light from the laser element. It is.

  More preferably, as described in claim 7, the object detection light receiver is provided on a back side of a laser element that irradiates a laser beam toward the object, and at a focal position of the objective lens. Just do it. The objective lens is preferably realized as a collimating lens that irradiates a measurement object with a laser beam output from the laser element as a substantially parallel light beam, as described in claim 8, for example.

  In addition to the laser state detection device described above, the present invention provides a light projecting element that irradiates light toward the measurement object, a light receiving element that receives reflected light from the measurement object, and light reception by the light receiving element. Constructing a laser state detection system comprising a photoelectric switch having an identification means for identifying the presence / absence of the measurement object from a quantity, and a determination means for determining the detection state of the laser state detection device from the identification result of the photoelectric switch It is characterized by.

  According to the laser measurement method of the present invention, the presence or absence of reflected light is determined by receiving reflected light from the measurement object independently of the laser light output from the laser element, and the laser element is determined based on the determination result. It can be determined whether or not modulated laser light is generated by the self-coupling effect of the laser light. Therefore, even when the interference component caused by the self-coupling effect cannot be detected, it is easy to determine whether the cause of the interference component is weak or the measurement object does not exist, and the measurement Reliability can be increased.

  Further, according to the laser state detection device having the above configuration, the self-coupling effect is generated in the state detection light receiver by the laser light output from the laser element, that is, the return light reflected by the measurement object and introduced into the laser element. Only the irradiation light on which the interference signal is superimposed is incident. On the other hand, only the return light reflected by the measurement object is introduced into the object detection light receiver, so the output of the object detection light receiver is monitored. By doing so, it is possible to reliably detect whether or not there is return light and, in turn, whether or not the measurement object exists. Further, since no return light enters the state detection light receiver, the interference component generated by the self-coupling effect in the laser element can be detected with high sensitivity (good S / N).

  In particular, if the state detection light receiver and the object detection light receiver are arranged in the above-described positional relationship with respect to the objective lens provided on the front surface (laser light emission surface) of the laser element, these two light receivers are arranged. Since it can be optically separated and positioned compactly, the overall structure can be easily made compact. In addition, if the light receiving device for detecting an object is arranged on the back surface side of the laser element and at the focal position of the objective lens, the light receiving efficiency of the returning light by the light receiving device for detecting the object can be increased, and the light receiving intensity can be increased. Thus, it is possible to sufficiently secure the detection sensitivity.

Hereinafter, a laser measurement method according to an embodiment of the present invention and a laser state detection device realized by applying the laser measurement method will be described with reference to the drawings.
The laser state detection device basically outputs a wavelength-modulated laser beam to irradiate the measurement object 2, and the return light (reflected laser light) of the laser beam reflected by the measurement object 2 is introduced. The semiconductor laser device 1 resonates due to the self-coupling effect with the irradiation laser beam. The laser state detection device further includes a state detection light receiver 3 that receives the output (laser light) of the laser element 1 resonated by the self-coupling effect and detects the light reception intensity, and the measurement object. 2 is provided with an object detection light receiver 5 that detects the presence or absence of reflected light (returned light) 2. Incidentally, the semiconductor laser element 1 comprises a VCSEL type laser diode (LD). Each of the state detection light receiver 3 and the object detection light receiver 5 includes a photodiode (PD).

  Here, it is assumed that the laser beam return light (reflected laser beam) output from the laser element 1 and reflected by the measurement object 2 is detected by the object detection light receiver 5. 1 illuminates auxiliary light having a wavelength different from that of the laser beam toward a measurement object 2 from another light source, for example, a light emitting diode (LED) 1a, and reflects the reflected light from the measurement object 2 of the auxiliary light. You may make it detect with the said light receiver 5 for a target object detection.

  For example, you may comprise said another light source and the light receiver 5 for a target object by what is called a reflection type photoelectric switch. A typical reflective photoelectric switch on the market is equipped with a light projecting element (light emitting diode) and a light receiving element (photodiode) in one housing, and emits light from the light projecting element toward the target space. When there is an object in the object space, the light reflected by the object is received by the light receiving element, and the presence or absence of the object is determined from the amount of light received. Therefore, the light projecting element of the reflective photoelectric switch is regarded as the above-mentioned “another light source”, the light receiving element of the reflective photoelectric switch is regarded as the object detection light receiver 5, and the laser element 1 and the state described above are regarded. If it is used together with the light receiver 3 for detection, the present invention can be implemented.

  In this case, it is also useful to irradiate the auxiliary light in a pulse shape and to modulate the wavelength of the laser light output from the laser element 1 in synchronization with the irradiation timing of the auxiliary light. That is, the rise and fall of the auxiliary light are used as a trigger for wavelength modulation of the laser element 1. In this way, it is possible to suppress noise caused by light that is input asynchronously and improve the SN ratio. In other words, it is possible to suppress unintended interference between the laser light and the auxiliary light.

  Now, this laser state detection device (laser measurement method) is characterized by the fact that the state detection light receiver 3 emits laser light emitted from the laser element 1 as shown in FIG. It is configured so as to receive light and not receive reflected light (return light) from the measurement object 2, that is, to receive only the laser light output from the laser element 1. The object detection light receiver 5 receives reflected light (return light) from the measurement object 2 and does not receive laser light emitted from the laser element 1, that is, only the reflected light. Is configured to receive light.

  Specifically, for example, as shown in FIG. 2, the laser element 1 is arranged with its laser emission surface facing the objective lens 4. Incidentally, the objective lens 4 is an aspherical lens, and is formed such that the focal length is short near the optical axis and gradually increases as it approaches the outer periphery. Then, laser light emitted in a conical or elliptical cone shape from the laser radiation surface is irradiated onto the measurement object 2 through the objective lens 4 as a substantially parallel optical path, and the laser light (return light) reflected by the measurement object 2 is irradiated. Is received through the objective lens 4.

  A spherical lens can also be used as the objective lens 4. In this case, it is desirable that the laser element 1 is disposed at the focal position of the objective lens 4 and the light receiving element 5 is disposed farther than the focal position. In FIG. 2, the optical axis of the laser beam and the optical axis of the objective lens 4 are provided coaxially, but may be provided non-coaxially. Further, in FIG. 2, the optical axis of the laser beam and the optical axis of the objective lens 4 are provided in parallel to each other, but can also be provided with an angle to each other.

  In the reflection type laser state detection device having such a state detection optical system, the state detection light receiver 3 is located on the side of the laser element 1 and directly receives the irradiation light output from the laser element 1 or A position where a part of the laser beam reflected by the objective lens 4 reaches and avoids a region where the return light reflected by the measurement object 2 is condensed via the objective lens 4 Is provided.

  In addition, about the reflection by the said objective lens 4, the reflection which arises on the surface by the side of the laser element 1 of the objective lens 4 may be used, or the reflection which arises on the surface by the side of the measuring object 2 of the objective lens 4 may be used. In order to improve the reflectance on the surface of the objective lens 4, for example, a reflecting means such as a metal reflecting film or a reflecting mirror may be provided on a part of the surface of the objective lens 4. Furthermore, if the total reflection generated on the surface of the objective lens 4 on the measurement object 2 side is used, a large reflectance can be obtained without providing special reflecting means.

The object detection light receiver 5 is an area where the irradiation light output from the laser element 1 is directly received or a part of the laser light reflected by the objective lens 4 does not reach, and the measurement is performed. The return light reflected by the object 2 is provided in a region where it is condensed via the objective lens 4.
That is, as the object detecting light receiver 5 (photodiode), one having a light receiving area larger than the outer shape of the laser element 1 (laser diode) is used. The object detection light receiver 5 is a region where the irradiation light output from the laser element 1 is not directly received, or a region where a part of the laser light reflected by the objective lens 4 does not reach. The return light reflected by the measurement object 2 is provided in a region where the return light is collected via the objective lens 4. Specifically, the light receiving device 5 for detecting the object is on the back side of the laser element 1 (on the opposite side of the laser emission surface), and is reflected by the measurement object 2 and collected via the objective lens 4 in particular. It is provided at a position where reflected reflected light (return light) converges, in other words, in the vicinity of the focal position by the outer peripheral portion of the aspheric objective lens 4. At this time, the light in the vicinity of the optical axis emitted from the laser element 1 is reflected by the surface of the objective lens 4 and returns to the laser element 1 as reflected light. However, since the object detection light receiver 5 is behind the laser element 1, it does not receive the reflected light.

  In this way, the state detection light receiver 3 and the object detection light receiver 5 are provided, respectively, and the irradiation light on which the interference signal is superimposed by the self-coupling effect in the laser element 1 and the reflected laser light from the measurement object 2 are respectively provided. According to the reflection type laser state detection device configured to detect, even if a situation in which the interference component cannot be detected from the output of the state detection light receiver 3, the output of the object detection light receiver 5 is detected. It is possible to determine whether or not the reflected laser beam from the measurement object 2 exists, that is, whether or not the measurement object 2 exists. Accordingly, the reason why the resonance component due to the self-coupling effect in the laser element 1 cannot be detected is, for example, that the driving condition of the laser element 1 is inappropriate and the interference component is weak, or the measurement object 2 itself does not exist. It is possible to easily and reliably determine whether it is caused by the above.

  In particular, according to the above-described configuration, since the object detection light receiver 5 is provided at the focal position of the objective lens 4, even if the return light (reflected laser light) from the measurement object 2 is weak, the weak light is weak. Effective light can be effectively converged and guided to the object detection light receiver 5, so that the light receiving efficiency with respect to the return light can be effectively increased, and highly sensitive return light detection can be performed. . In particular, since the object detection light receiver 5 is arranged on the back side of the laser element 1, the return light condensed through the objective lens 4 passes through the periphery of the laser element 1 and is on the back side of the laser element 1. Therefore, the return light can be reliably detected. In addition, since the output laser beam from the laser element 1 and the laser beam reflected by the objective lens 4 do not enter the object detection light receiver 5, the detection of the return light described above is performed with good S / N. Can do.

  On the other hand, since the return light reflected by the measurement object 2 does not reach the state detection light receiver 3, the state detection light receiver 3 has a laser beam (self-coupled) output from the laser element 1. When the effect is generated, only the irradiation light on which the interference signal is superimposed can be accurately detected. Therefore, even if the resonance component generated by the self-coupling effect in the laser element 1 is weak, the interference component is not buried in the disturbance light component or the like, so that the detection accuracy for the interference component can be easily increased. .

  In terms of structure, the object detection light receiver 5 may be disposed on the back side of the laser element 1 and the state detection light receiver 3 may be disposed on the side of the laser element 1, so that the overall structure is compact. Therefore, it is possible to easily reduce the size. Therefore, for example, as shown in FIG. 3, the objective lens 4 is attached to the front end opening of the bottomed cylindrical metal can 11, and the laser element 1 is buried in the concave portion on the back side of the objective lens 4 and further disposed. If the circuit board 12 on which the state detection light receiver 3 and the object detection light receiver 5 are mounted is attached to the rear surface side opening (base) of the sensor 11, a so-called TO package type sensing unit of the reflection type laser state detection device. Can be easily constructed. FIG. 3 shows an example in which two state detection light receivers 3 are provided symmetrically around the optical axis of the laser element 1. In this example, the laser light output from the laser element 1 is reflected by the inner surface of the objective lens 4 and guided to the state detection light receiver 3.

  Alternatively, for example, it may be configured as shown in FIG. That is, the metal case 100 is formed in a cylindrical shape with a bottom, and has a circular opening 102 in the bottom 101 exhibiting an inclination α. A glass-made plano-convex lens 4 is provided obliquely on the inner side of the case 100 of the opening 102 with its convex surface facing the opening 102, and the low melting point glass 103 is placed so as to surround the entire outer periphery of the lens 4. The lens 4 is fixed to the case 100 by melting and solidifying. As materials for the case 100, the lens 4, and the low melting point glass 103, materials having similar thermal expansion coefficients and excellent adhesion are respectively selected, and the sealed state between the lens 4 and the opening 102 is selected. Is preserved.

  On the other hand, the end of the case 100 is closed with a metal disk-shaped substrate 110. That is, the flange-shaped portion formed on the outer periphery of the end portion of the case 100 and the flange-shaped portion formed on the outer periphery of the substrate 110 are in close contact and are welded and sealed all around. Metal pins 111 are respectively inserted into the plurality of through holes formed in the substrate 110. Between them, the low melting point glass 112 is melted and solidified, and the pin 111 is fixed to the substrate 110. As the materials of the substrate 110, the pins 111, and the low melting point glass 112, materials having similar thermal expansion coefficients and excellent adhesion are respectively selected, and the sealed state between the substrate 110 and the pins 111 is maintained. As it sags, electrical insulation is maintained.

  Further, a metal support 113 is fixed inside the substrate 110, and the laser element 1 is bonded and fixed to the tip thereof with the laser emission surface 11 facing the lens 4. Light receiving elements 3 and 5 are bonded and fixed to the substrate 110 with the light receiving surface facing the lens 4 side. In particular, the light receiving element 5 is on the back side of the laser element 1 and is irradiated from the laser element 1. The laser beam reflected by the lens 4 is provided at a position where it does not reach. The light receiving element 3 is provided at a position where the laser light (returned light) reflected by the measurement object 2 is not collected via the lens 4, specifically, at the edge side of the substrate 110.

  The terminals of the laser element 1 and the light receiving elements 3 and 5 and the pins 111 are electrically connected by a conductive wire (not shown), so that power is supplied from the outside and connected to the outside. Signal extraction is possible. A ground pin 115 is provided on the substrate 110, and the ground pin 115 is electrically connected to the substrate 110 and the support column 113. The laser element 1 is grounded to the substrate 110 on its back surface, and the light receiving element 3 is grounded to the support column 113 on its back surface.

  The positional relationship shown in FIG. 2 is adopted for the laser element 1, the lens 4, and the light receiving elements 3 and 5. That is, the optical axis of the laser element 1 is slightly displaced without passing through the principal point of the lens 4, and the optical axis of the laser element 1 and the optical axis of the lens 4 form an inclination α. The outer edge portion 120 of the laser light emitted conically from the laser emitting surface 11 of the laser element 1 is reflected by the surface 44 of the lens 4 and emitted to the side of the lens 4 and is received by the light receiving element 3. When the laser beam 120 is incident on the lens 4, a part 121 thereof is reflected by the inner surface 43 of the lens 4, but the positional relationship of each part is considered in advance so that it is not received by the light receiving element 3. ing. At this time, if the inner space of the can package is filled with an inert gas, the laser element 1 can be prevented from deteriorating and the life can be extended. Note that the plane side of the plano-convex lens 4 may be arranged toward the outside of the package, and total reflection generated on the plane side may be used. In this case, the inclination α of the lens 4 can be reduced. Further, as described above, when the convex surface side of the lens 4 is arranged toward the outside of the package, total reflection generated on the convex surface side may be used.

  Thus, according to the reflection type laser state detection apparatus configured as described above, only the reflected light from the measurement object 2 is detected when the state of the measurement object 2 is detected using the self-coupling effect in the laser element 1. Since the object detection light receiver 5 is provided, and the state detection light receiver 3 is configured to detect only the laser light output from the laser element 10, the reflected light (return light) of the measurement object 2 is detected. The state of the measurement object 2 can be accurately detected while easily confirming the presence / absence, and hence the presence of the measurement object 2. In addition, the layout of the laser element 1 and the light receivers 3 and 5 can be made compact by arranging the object detection light receiver 5 on the back side of the laser element 1, particularly when these are packaged integrally. Has a great practical effect, such as being able to easily reduce its size.

  The present invention is not limited to the embodiment described above. In the embodiment, the objective lens 4 is arranged so as to be orthogonal to the optical axis of the laser light emitted from the laser element 1, but the objective lens 4 is arranged so as to be inclined with respect to the optical axis, and a state detection light receiver. The reflection direction of the laser beam with respect to 3 may be further directed outward. Even if the objective lens 4 is tilted in this way, the optical path of the return light collected through the objective lens 4 hardly changes. It is sufficient to arrange it on the back side of the laser element 1 in the same manner as in FIG. Further, since the reflection angle of the light output from the laser element 1 can be increased, it is possible to reliably prevent the return light from entering the state detection light receiver 3. As the objective lens 4, it is of course possible to use a double-sided convex lens instead of the exemplified single-sided convex lens. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

The figure which shows the schematic optical system in enforcing the laser measuring method which concerns on one Embodiment of this invention. The figure which shows schematic structure of the laser state detection apparatus which concerns on one Embodiment of this invention. The figure which shows the specific structural example of a laser state detection apparatus. Sectional drawing which shows the more specific structural example of a laser state detection apparatus. The figure which shows the basic composition of the laser state detection apparatus using a self-coupling effect. The figure which shows the concept of the modulation | alteration laser beam produced by the self-coupling effect of a laser beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser element 1a Light source 2 Object to be measured 3 Light receiver for state detection 4 Objective lens 5 Light receiver for object detection

Claims (9)

A semiconductor laser element that irradiates the measurement target with wavelength-modulated laser light and introduces the laser light reflected by the measurement target is used, and an interference signal generated by a self-coupling effect in the laser element is generated. When detecting the superimposed irradiation light and detecting the state of the measurement object,
A laser measurement method, wherein the presence or absence of the measurement object is detected by receiving reflected light from the measurement object independently of the irradiation light.   The reflected light from the measurement object that is detected independently of the irradiation light is a reflected light component of laser light emitted from the laser element toward the measurement object, and the irradiation light is the measurement object. The laser measurement method according to claim 1, wherein the reflected light from the object is detected by blocking and the reflected light from the measurement object is detected by blocking the irradiation light.   The reflected light by the measurement object detected independently of the irradiation light is a reflected light component of auxiliary light emitted from a light source different from the laser element toward the measurement object, and the measurement object The laser measurement method according to claim 1, wherein reflected light from an object is detected by blocking the irradiation light. A semiconductor laser element that irradiates the measurement target with wavelength-modulated laser light and introduces the laser light reflected by the measurement target is used, and an interference signal generated by a self-coupling effect in the laser element is generated. A laser state detection device that analyzes the superimposed irradiation light and detects the state of the measurement object,
A laser state comprising: a state detection light receiver provided so as to be able to receive only the irradiation light of the laser element; and a target detection light receiver provided so as to be able to receive only reflected light from the object Detection equipment. The state detection light receiver is capable of receiving the irradiation light from the laser element, and is provided at a position where the reflected light from the measurement object does not reach,
5. The laser state detection according to claim 4, wherein the light receiving device for detecting an object is provided at a position where reflected light from the measurement object arrives and irradiation light from the laser element does not reach. machine. A semiconductor laser element that irradiates the measurement target with wavelength-modulated laser light and introduces the laser light reflected by the measurement target is used, and an interference signal generated by a self-coupling effect in the laser element is generated. A laser state detection device that analyzes the superimposed irradiation light and detects the state of the measurement object,
A state detection light receiver provided to receive only the irradiation light of the laser element;
A light source that emits auxiliary light toward the measurement object;
An apparatus for detecting a laser state, comprising: an object detection light receiver provided so as to be able to receive only the reflected light of the auxiliary light reflected by the object by blocking the irradiation light from the laser element. The laser element irradiates a measurement object with laser light through an objective lens,
7. The laser according to claim 5, wherein the light receiving device for detecting an object is provided on a back surface side of a laser element that irradiates laser light toward the object, and is provided at a focal position of the objective lens. Condition detection device.   The laser condition detection device according to claim 5 or 6, wherein the objective lens irradiates a measurement object with a laser beam output from the laser element as a substantially parallel light beam. A semiconductor laser element that irradiates the measurement target with wavelength-modulated laser light and introduces the laser light reflected by the measurement target is used, and an interference signal generated by a self-coupling effect in the laser element is generated. The laser state detection device according to any one of claims 4 to 8, which detects the state of the measurement object by analyzing the superimposed irradiation light;
A light projecting element that emits light toward the measurement object; a light receiving element that receives reflected light from the measurement object; and an identification unit that identifies the presence or absence of the measurement object from the amount of light received by the light receiving element. A photoelectric switch;
A laser state detection system comprising: a determination unit that determines a detection state of the laser state detection device from a result of identification of the photoelectric switch.

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