JP2012247255A - Laser displacement gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser displacement gauge which is capable of measuring a distance in simple configuration.SOLUTION: A laser displacement gauge comprises: a light source section 11 which emits laser light; a light flux diameter change section 14 which expands a light flux diameter of emitted light and converges reflection light obtained by reflecting the expanded emitted light in reflection means 30; a light receiving section 16 which receives the reflection light; a calculation section 18 which calculates a distance to the reflection means 30 by using the emitted light and the reflection light; a displacement detection section 21 which detects displacement of the distance; a displacement output section 22 which performs output relating to the detected displacement; and a reflection section 17a which causes the light flux diameter change section 14 to transmit or reflect the emitted light from the light source section 11 via a center area by transmitting either the emitted light prior to expansion or the reflection light from the light flux diameter change section 14 therethrough and reflecting the other light, and causes the light receiving section 16 to reflect or transmit therethrough the reflection light from the light flux diameter change section 14 via an outside area that is an area outside the center area. Regarding the light flux diameter change section 14, an effective aperture with respect to reflection light is larger than a light flux diameter of emitted light.

Description

  The present invention relates to a laser displacement meter that measures a distance to a reflecting means using laser light and detects a change in the distance.

  In the conventional laser displacement meter, if there are obstacles such as raindrops, snow, mist, dirt, vegetation, etc. in the laser beam path, the intensity of the emitted light and reflected light is attenuated, resulting in a decrease in accuracy. For this reason, measures such as increasing the intensity of the laser beam were taken, but due to safety issues in the human body, recently, a diffusion-type laser displacement that reduces the influence of obstacles by diffusing the laser beam. A total has been developed.

  In the optical means of this diffusion type laser displacement meter, an optical system that emits laser light toward the reflecting means, and a twin-lens type that separately provides an optical system that receives the reflected light reflected by the reflecting means, A single-lens system sharing a part of optical means is known. In the single-lens laser displacement meter, the optical axis of the emitted outgoing light and the optical axis for receiving the reflected light can be shared, and the price can be reduced according to the sharing of the lens components. However, since the light source that emits the laser light is different from the light receiving unit that receives the reflected light, a separation unit that finally separates the optical path is required. As this separation means, for example, a half mirror, a quarter-wave plate, a deflecting prism, or the like has been used (see, for example, Patent Document 1).

JP 2005-156330 A

  However, in the conventional laser displacement meter using a half mirror, the transmittance and the reflectance of the half mirror are 50%, respectively, so that the amount of reflected light received by the half mirror is emitted. It was reduced to less than a quarter of the light, leading to a decrease in measurement accuracy and being easily affected by obstacles. Further, in a conventional laser displacement meter using a quarter-wave plate and a deflecting prism, the decrease in the amount of received light can be reduced, but there has been a problem of high accuracy and high price of the optical system.

  The present invention has been made in order to solve the above-described problem, and a laser capable of reducing the attenuation of the laser beam while the outgoing light and the reflected light pass through the same optical system and has a simple configuration. An object is to provide a displacement meter.

In order to achieve the above object, a laser displacement meter according to the present invention expands the diameter of a light source unit that emits laser light and the diameter of the emitted light that is laser light emitted from the light source unit, and reflects the expanded outgoing light. A light beam diameter changing unit for collecting the reflected light reflected by the means, a light receiving unit for receiving the reflected light, a calculating unit for calculating the distance to the reflecting means using the emitted light and the reflected light, and a calculating unit A storage unit for storing the distance calculated by the above, a displacement detection unit for detecting the displacement of the distance to the reflecting means using the distance stored by the storage unit, and a displacement output for outputting the displacement detected by the displacement detection unit The light emitted from the light source part is transmitted through the central region by transmitting one of the light emitted from the light source part and the unexpanded light emitted from the light source part and the reflected light from the light beam diameter changing part and reflecting the other. The light beam diameter change part is transmitted or reflected to change the light beam diameter. A reflecting portion that reflects or transmits reflected light from the light receiving portion to the light receiving portion through an outer region that is an outer region of the central region, and the light beam diameter changing unit has a light beam whose effective aperture with respect to the reflected light is emitted light. It is larger than the diameter.
With such a configuration, the outgoing light and the reflected light can be separated without using a half mirror or a prism, and the attenuation of the laser light is reduced by appropriately setting the ratio between the central region and the outer region. be able to. Also, a simpler configuration can be achieved than when a prism is used.

In the laser displacement meter according to the present invention, the light beam diameter changing unit includes a diverging lens that diverges outgoing light before expansion and a converging lens that converges outgoing light that has passed through the diverging lens, and The lens and the converging lens are annular lenses in which two lenses having different focal lengths are formed concentrically, and the magnification using the central portion of the diverging lens and the converging lens is determined by the diverging lens and the converging lens. It may be larger than the magnification using the outer peripheral portion.
With such a configuration, it is possible to further reduce the attenuation ratio of the reflected light by the central region of the light beam diameter changing portion.

Further, in the laser displacement meter according to the present invention, the reflecting unit transmits the light emitted from the light source unit to the light beam diameter changing unit through the central region, and the reflected light from the light beam diameter changing unit is transmitted through the outer region. You may reflect on a light-receiving part.
In the laser displacement meter according to the present invention, the reflecting portion may have a hole through which the outgoing light passes in the central region, and a mirror surface may be provided in the outer region.
Further, in the laser displacement meter according to the present invention, the reflection unit reflects the emitted light from the light source unit to the light beam diameter changing unit through the central region, and reflects the reflected light from the light beam diameter changing unit through the outer region. You may permeate | transmit to a light-receiving part.
Further, in the laser displacement meter according to the present invention, the reflecting portion may be formed of a transmissive member provided with a mirror surface that reflects the emitted light in the central region, and the outer region transmitting the reflected light from the light beam diameter changing portion. .

  According to the laser displacement meter of the present invention, the emitted light and the reflected light can be separated without using a half mirror or a prism, and the attenuation of the laser light can be reduced.

The figure which shows the structure of the laser displacement meter by Embodiment 1 of this invention. The figure for demonstrating the reflection part in the embodiment Flowchart showing the operation of the laser displacement meter according to the same embodiment The figure which shows the other structure of the laser displacement meter by the embodiment The figure for demonstrating another example of the reflection part in the embodiment The figure which shows the other structure of the laser displacement meter by the embodiment The figure which shows the other structure of the light beam diameter change part by the embodiment

  Hereinafter, a laser displacement meter according to the present invention will be described using embodiments. In the following embodiments, components and steps denoted by the same reference numerals are the same or equivalent, and repetitive description may be omitted.

(Embodiment 1)
A laser displacement meter according to Embodiment 1 of the present invention will be described with reference to the drawings. In the laser displacement meter according to the present embodiment, the outgoing light and the reflected light pass through the same optical system, and one of the outgoing light and the reflected light is transmitted and the other is reflected by the reflecting portion. .

  FIG. 1 is a diagram showing a configuration of a laser displacement meter 1 according to the present embodiment. The laser displacement meter 1 according to the present embodiment includes a light source unit 11, a light beam diameter changing unit 14, a lens 15, a light receiving unit 16, a reflecting unit 17a, a calculating unit 18, a storage unit 19, and a storage unit 20. And a displacement detection unit 21 and a displacement output unit 22.

  The light source unit 11 emits laser light. The light source unit 11 may generate and emit laser light with a laser diode, for example. The wavelength of the laser beam does not matter. The laser light may be, for example, red laser light having a wavelength of about 650 nm, or laser light having other wavelengths. The diameter of the laser beam emitted from the light source unit 11 may be about 2 mm, or may be another diameter. However, a smaller diameter of the laser beam from the light source unit 11 is preferable. This is because the diameter of the hole 31 described later can be reduced.

  The light beam diameter changing unit 14 receives the emitted light, which is laser light emitted from the light source unit 11, via the central region of the reflecting unit 17a, and expands the light beam diameter of the emitted light. In addition, the light beam diameter changing unit 14 condenses the reflected light, which is the expanded outgoing light reflected by the reflecting means 30, on the reflecting unit 17a. Condensing the reflected light means reducing the beam diameter of the reflected light. At the time of the condensing, the light beam diameter changing unit 14 condenses the reflected light in a region wider than the central region of the reflecting unit 17a. That is, the light beam diameter changing unit 14 has an effective aperture for the reflected light larger than the light beam diameter of the outgoing light passing through the light beam diameter changing unit 14. For example, at the position of the lens 13, the effective aperture of the lens 13 with respect to the reflected light is larger than the luminous flux diameter of the outgoing light passing through the lens 13. As a result, it is possible to make the light beam diameter of the reflected light larger than the light beam diameter of the emitted light at the position of the reflecting portion 17a. In this way, at the position of the reflecting portion 17a, in order to make the emitted light have a small luminous flux diameter and the reflected light has a large luminous flux diameter, for example, the lenses 12 and 13 transmit the emitted light only near the center of the lens. The size of the lenses 12 and 13, the focal length, the distance between the lenses, and the like may be set so that the reflected light is condensed using the entire lens. In addition, the optical system of the light beam diameter changing unit 14 may be adjusted so that the emitted light emitted from the light beam diameter changing unit 14 has a divergence angle that expands as the diameter approaches the reflecting unit 30. Or you may adjust the optical system of the light beam diameter change part 14 so that the emitted light radiate | emitted from the light beam diameter change part 14 may become parallel light.

  Here, the reflecting means 30 may be a retroreflecting plate in which incident light and reflected light are in the same direction regardless of the incident angle, or a reflecting plate (for example, a mirror) that is not a retroreflective plate. Also good. When the reflecting means 30 is a retroreflecting plate, for example, a corner cube mirror or a corner cube prism may be used, or a fine glass bead may be used. Further, the reflecting surface of the reflecting means 30 may be a flat surface or a curved surface. When the reflecting means 30 is a retroreflecting plate, the outgoing light and the reflected light pass through substantially the same optical path, and it is considered that the diameters of the outgoing light and the reflected light at the reflecting portion 17a are the same. . However, although the laser light is coherent light, the divergence angle is not completely zero. Further, even in the retroreflective plate, the directions of the outgoing light and the reflected light are not exactly the same, and some differences occur depending on manufacturing errors and the like. Furthermore, the distance from the laser displacement meter 1 to the reflecting means 30 is usually a relatively long distance such as 50 m or 100 m. As a result, even if the reflecting means 30 is a retroreflecting plate, the reflected light has a larger beam diameter than the emitted light.

  In the present embodiment, the light beam diameter changing unit 14 includes a lens 12 that is a diverging lens and a lens 13 that is a converging lens, and both expand the diameter of emitted light and reduce the diameter of reflected light. That is, the light beam diameter changing unit 14 is a so-called beam expander. With respect to the emitted light, the lens 12 diverges the emitted light before expansion, and the lens 13 converges the emitted light that has passed through the lens 12. That is, the divergence angle of the emitted light is increased by the lens 12, and the divergence angle of the emitted light is decreased by the lens 13. On the other hand, with respect to the reflected light, the lens 13 converges the reflected light before condensing, and the lens 12 diverges the reflected light that has passed through the lens 13. That is, the spread angle of the reflected light is reduced by the lens 13, and the spread angle of the reflected light is increased by the lens 12. In addition, although the case where a plano-concave lens that is a diverging lens and a plano-convex lens that is a converging lens are used as the lenses 12 and 13 is shown here, the luminous flux diameter of the emitted light is changed by a combination of other lenses. Needless to say, the beam diameter of the reflected light may be reduced by expanding.

  The lens 15 is a plano-convex lens that condenses the reflected light on the light receiving unit 16. The reflected light is reflected by the reflecting portion 17a. Further, the lens 15 may be other than a plano-convex lens as long as the reflected light can be condensed on the light receiving unit 16.

  The light receiving unit 16 receives reflected light. The light receiving portion 16 may be any device that can detect light, and may be, for example, a photodiode or a phototransistor.

  The reflection unit 17a transmits one of the outgoing light before expansion emitted from the light source unit 11 and the reflected light from the light beam diameter changing unit 14, and reflects the other. By doing so, the reflection unit 17a transmits (or reflects) the emitted light from the light source unit 11 to the light beam diameter changing unit 14 through the central region, and the reflected light from the light beam diameter changing unit 14 is The light receiving unit 16 reflects (or transmits) the light through the outer region that is an outer region of the central region. Here, when the reflecting portion 17a transmits one of the outgoing light and the reflected light and reflects the other, it means that all of the outgoing light is transmitted or reflected. It means that most (the part incident on the outer region) is reflected or transmitted. In the present embodiment, as shown in FIG. 1, the reflection unit 17 a transmits the light emitted from the light source unit 11 to the light beam diameter changing unit 14 through the central region, and from the light beam diameter changing unit 14. The case where the reflected light is reflected on the light receiving unit 16 through the outer region will be described. That is, the emitted light passes through the central region of the reflecting portion 17 a and enters the light beam diameter changing portion 14. The reflected light is reflected by the outer region of the reflecting portion 17 a and enters the light receiving portion 16 through the lens 15. In the opposite case, that is, the emitted light from the light source unit 11 is reflected by the light beam diameter changing unit 14 through the central region, and the reflected light from the light beam diameter changing unit 14 is transmitted to the light receiving unit 16 through the outer region. This case will be described later with reference to FIG. Here, the transmission may mean that light passes through a transparent member such as glass or highly transparent resin, or where there is no such a solid medium (for example, in the air or in a vacuum). It may be that light passes through. Moreover, the reflection part 17a is normally provided so that it may have an angle of about 45 degree | times with respect to the optical path of the laser beam radiate | emitted from the light source part 11. FIG. Moreover, it is preferable that the diameter of the reflection part 17a is the same as that of the reflected light which the light beam diameter change part 14 condenses, or larger than it.

In the present embodiment, as shown in FIG. 2A, it is assumed that a hole 31 through which outgoing light passes is provided in the central region of the reflecting portion 17a. The hole 31 is a through hole. The size of the hole 31 in the central region is preferably as small as possible within a range where the laser light passing through the hole 31 does not hit the reflecting portion 17a. For example, the size of the hole 31 may be slightly larger than the diameter of the laser beam emitted from the light source unit 11. As shown in FIG. 2, the hole 31 may be circular or may not be circular. As shown in FIG. 1, the reflection portion 17 a is inclined by about 45 degrees with respect to the emitted light. Therefore, when the hole 31 that is a circle when viewed from the same direction as the emitted light is provided, the hole 31 is When viewed from the front direction of the reflecting portion 17a, the shape is elliptical. For example, the major axis, which is the length of the ellipse in the major axis direction, is slightly larger than (laser beam diameter) × ^2½ , and the minor axis, which is the length of the ellipse in the minor axis direction, is The diameter is slightly larger than the diameter of the laser beam. As with the shape of the hole 31, the outer shape of the reflecting portion 17a may be an elliptical shape instead of a circular shape. Moreover, the hole 31 may be provided so as to be a circle when viewed from the optical axis direction of the reflected light, or may be provided so as to be a circle when viewed from the direction facing the reflecting portion 17a. In addition, a mirror surface 32 is provided in an outer region that is outside the hole 31 in the central region of the reflecting portion 17a. The mirror surface 32 may be, for example, a metal having a high reflectance such as silver or aluminum plated on glass or transparent resin (for example, electroplating, chemical plating, vapor deposition, or the like) or having a high reflectance. A metal plate itself or a metal film having a high reflectivity may be attached to another plate.

  Note that the reflecting portion 17a is not provided with the hole 31 in the central region, and a transmissive member may exist in the central region. For example, as shown in FIG. 2B and FIG. 2C, the reflecting portion 17a is mirror-exposed on the outer region other than the central region of the transmissive member 34, which is disc-shaped glass or highly transparent resin. 33 may be provided. FIG.2 (c) is sectional drawing which passes along the center of the reflection part 17a shown by FIG.2 (b). As described above, the mirror surface 33 may be formed by plating the transmissive member 34 with a metal having a high reflectivity, or may be a plate or film having a high reflectivity adhered to the transmissive member 34. Good. The mirror surface 33 may be provided on the laser light incident surface of the reflecting portion 17a, that is, the light source portion 11 side, or the mirror surface 33 may be provided on the opposite side. Even in such a case, the emitted light can pass through the central region, and the reflected light can be reflected in the outer region. In the present embodiment, the case where the reflecting portion 17a is provided with the hole 31 in the central region will be mainly described.

The calculating unit 18 calculates the distance to the reflecting means 30 using the emitted light and the reflected light. The calculation unit 18 measures a time Δt from when the laser light is emitted from the light source unit 11 until it is received by the light receiving unit 16. Then, by using the Δt, the distance L from the light source unit 11 to the reflecting means 30 can be calculated as L = (c × Δt) / 2. Here, c is the speed of light in the atmosphere. Further, this distance L is sometimes referred to as a baseline length. Further, when it is desired to measure the distance from another position instead of the baseline length, the correction amount may be added or subtracted as appropriate to the baseline length distance L. The baseline length is usually from about 2 m to about 200 m. The base line length may be about 10 m to about 100 m. Further, the calculation unit 18 may calculate the time Δt using, for example, the phase of the laser beam, may be calculated by measuring the time from the laser beam emission timing to the light reception timing, or It may be calculated by other methods. For the distance calculation method by the calculation unit 18, refer to, for example, the above-mentioned Patent Document 1 and the following document.
References: Hiroshi Naya, Masahiro Mizogami, Soichiro Asari, Tomohiro Masunari, Noriichi Shimizu, Hiroyuki Maeda, “Development of a diffusion laser displacement meter and verification of its practicality”, Journal of the Japan Landslide Society, Vol. 44, no. 6, p339-348, 2008

  In addition, the calculation unit 18 may, for example, always measure the distance, or periodically (for example, every minute, every five minutes, every ten minutes, every hour, every six hours, The distance may be measured every 12 hours, every 24 hours, etc., or irregularly (for example, timing according to detection of occurrence of some event). When measuring the distance regularly, the calculation unit 18 may determine whether it is time to perform measurement using, for example, a clock unit or a clock unit (not shown). In addition, the emission time of the laser light in one measurement may be, for example, 4 seconds or less, or 1 second or less. Further, the calculation unit 18 may calculate the distance a plurality of times and calculate an average of the distances as the final distance. By doing so, distance errors can be reduced. The calculation unit 18 also performs control processing for driving the light source unit 11 to emit laser light, and signal processing for performing amplification, waveform shaping, peak hold, and the like on an output signal corresponding to light reception from the light receiving unit 16. Means, a time measuring means for measuring time using a clock or the like may be provided.

The accumulation unit 19 accumulates the distance calculated by the calculation unit 18 in the storage unit 20.
In the storage unit 20, the distance calculated by the calculation unit 18 is stored. The distance is accumulated by the accumulation unit 19 as described above. The storage unit 20 can be realized by a predetermined recording medium (for example, a semiconductor memory, a magnetic disk, an optical disk, etc.). The storage in the storage unit 20 may be temporary storage in a RAM or the like, or may be long-term storage.

  The displacement detection unit 21 detects a change in the distance to the reflection means 30 using the distance accumulated in the storage unit 20 by the accumulation unit 19. The detection may be, for example, that the difference between the distance calculated last time and the distance calculated this time exceeds a predetermined threshold, and the average of previously calculated distances. And the distance calculated this time may exceed a predetermined threshold value, or the difference between the distance calculated as a reference and the distance calculated this time may be It may be that a predetermined threshold value has been exceeded. The distance calculated as the reference may be the distance calculated for the first time.

  When the displacement detector 21 detects a change in the calculated distance, the displacement output unit 22 performs an output related to the displacement. The output may be, for example, an output of a displacement amount, an output indicating that a displacement is detected, an output of a warning that a displacement is detected, or an output related to other displacements. . The output may be displayed on a display device (for example, a CRT or a liquid crystal display), may be transmitted via a communication line to a predetermined device, may be printed by a printer, The light may be turned on, the sound may be output by a speaker, the warning sound may be output by a siren, stored in a recording medium, or delivered to another component. The displacement output unit 22 may or may not include an output device (for example, a display device or a printer). Further, the displacement output unit 22 may be realized by hardware, or may be realized by software such as a driver for driving these devices. In the present embodiment, a case will be described in which the displacement output unit 22 transmits information indicating that a displacement has been detected and the amount of displacement.

  In addition, each component of the laser displacement meter 1 is, for example, dustproof and waterproof, and may be provided inside a housing that is resistant to temperature changes. Such a laser displacement meter 1 can be used for measurement of distance over a long period in the field. Moreover, the housing | casing may be made into the vibration proof process, for example.

Next, the operation of the laser displacement meter 1 will be described using the flowchart of FIG.
(Step S101) The calculation unit 18 determines whether it is time to calculate the distance. If it is time to calculate the distance, the process proceeds to step S102. If not, the process in step S101 is repeated until the time to calculate the distance is reached. Note that, as described above, the calculation unit 18 may determine, for example, that it is a timing for periodically calculating the distance, or a timing for calculating the distance according to the occurrence of another event or the like. You may judge.

  (Step S102) The calculation unit 18 controls the light source unit 11 to emit pulsed laser light. As a result, laser light is emitted from the light source unit 11. Then, the laser light is incident on the light beam diameter changing portion 14 through the hole 31 in the central region of the reflecting portion 17 a, and the light beam diameter is expanded by the lenses 12 and 13 to be applied to the reflecting means 30. The reflected light from the reflecting means 30 is condensed on the mirror surface 32 of the reflecting portion 17 a by the lenses 13 and 12 of the light beam diameter changing portion 14. Then, the reflected light reflected by the mirror surface 32 is collected through the lens 15 and received by the light receiving unit 16.

  (Step S103) The calculation unit 18 measures the time Δt related to the laser light, and calculates the distance L to the reflecting means 30 using the time Δt.

  (Step S104) The calculation unit 18 determines whether to repeat the distance calculation. If so, the process returns to step S102. If not, the average of the distances calculated so far is calculated, and the process proceeds to step S105. For example, when the distance is calculated a predetermined number of times (for example, 4 or 5 times), the calculation unit 18 determines that the distance is not repeated, and calculates the distance. When the number of times is less than the determined number, it may be determined that the number of times is repeated.

  (Step S <b> 105) The storage unit 19 stores the distance calculated by the calculation unit 18 in the storage unit 20. Note that the accumulation target distance is an average of distances repeatedly calculated.

  (Step S106) The displacement detection unit 21 determines whether there is a change in the distance using the latest accumulated distance and the distance accumulated so far. And when there exists a change, it progresses to step S107, and when that is not right, it returns to step S101. Note that when the distance is calculated for the first time, there is no distance to be compared, and the presence or absence of a change in the distance cannot be determined. Therefore, the process may return to step S101.

(Step S107) The displacement output unit 22 performs an output related to the displacement detected by the displacement detection unit 21. Then, the process returns to step S101.
In the flowchart of FIG. 3, the process ends when the power is turned off or the process is terminated. In the flowchart of FIG. 3, when the distance measurement is not repeated, the process may proceed from step S103 to step S105.

Next, the operation of the laser displacement meter 1 according to the present embodiment will be described using a specific example.
In this specific example, it is assumed that the laser displacement meter 1 and the reflecting means 30 are installed on both banks across the river, and in particular, the reflecting means 30 is installed on the upper side of the mountain. In addition, the place where the reflection means 30 is installed is a place where a landslide is normally predicted. Therefore, the laser displacement meter 1 can detect a small amount of landslide that occurs as a precursor to a landslide, which can be used for disaster prevention. Moreover, in this specific example, the displacement output part 22 shall transmit the information regarding a displacement to the server of the disaster prevention base decided beforehand. In this specific example, it is assumed that distance is measured every hour (every hour), four distances are calculated by one measurement, and averaged.

  Suppose one day is 1 am. Then, the calculation unit 18 determines to start measurement (step S101), controls the light source unit 11, and emits laser light. In this specific example, the light source unit 11 is assumed to be a class 2 laser product of 1 mW or less. In this specific example, it is assumed that the lens 12 has a diameter of 20 mm, and the lens 13 has an effective aperture of 48 mm. The emitted laser beam has a diameter of about 4 mm, for example, but is expanded to about 13 mm by the lenses 12 and 13 and becomes a laser beam having a diameter of about 20 cm at the position of the reflecting means 30 separated by 100 m. . The reflected light of the laser beam is focused to a parallel light beam having a diameter of about 14 mm through the lenses 13 and 12, reflected by the reflecting unit 17 a, and condensed on the light receiving unit 16 through the lens 15. Then, when the reflected light is received by the light receiving unit 16 (step S102), the calculation unit 18 calculates the round trip time Δt1 of the laser beam using the reflected light. The calculating unit 18 substitutes the time Δt1 into the above-described equation, calculates the distance L1 to the reflecting means 30, and temporarily stores it on a recording medium (not shown) (step S103). Further, the calculation unit 18 repeats the calculation of the distance three more times, calculates the distances L2, L3, and L4, accumulates them in a recording medium (not shown), and averages the distance AL50 (= the average of the distances L1 to L4). (L1 + L2 + L3 + L4) / 4) is calculated and passed to the storage unit 19 (steps S102 to S104). The accumulation unit 19 accumulates the distance AL50 in the storage unit 20 in association with the date and time at that time (step S105). In the case where there are no obstacles such as raindrops or vegetation in the optical path of the laser beam, and the baseline length is about 50 m, the measurement error is about ± 0.2 mm.

  When detecting that the new distance AL50 has been accumulated, the displacement detection unit 21 calculates the absolute value of the difference between the distance AL1 corresponding to the oldest date and time stored in the storage unit 20 and the new distance AL50. Assume that the absolute value of the difference is AD50. Then, the displacement detection unit 21 reads a threshold value T stored in advance on a recording medium (not shown), and determines whether the AD 50 exceeds T. In this case, it is assumed that it was not exceeded. Then, the displacement detection unit 21 determines that there is no displacement, and no output relating to the displacement is performed (step S106).

  It is assumed that the difference AD50 between the new distance AL50 and the oldest distance AL1 exceeds the threshold value T. Then, the displacement detection unit 21 passes the fact and the distance difference AD50 to the displacement output unit 22. Then, the displacement detector 21 transmits the fact that the displacement is detected and the displacement AD50 to a predetermined transmission destination (step S107). In response to the reception, the server (not shown) that has received it can issue a landslide warning to the area or go around the mountain as appropriate. In this way, landslides can be detected in advance, and for example, accidents can be prevented or safety can be ensured.

Here, the conditions when the laser displacement meter 1 according to the present embodiment is less attenuated by the laser beam than the laser displacement meter using the half mirror described in Patent Document 1 will be described. In order to simplify the explanation, the ratio of the laser displacement meter according to Patent Document 1 receiving the reflected light from the reflecting means with respect to the emitted laser light, and the laser displacement meter 1 according to this embodiment are the reflecting means. It is assumed that the ratio of receiving the reflected light from 30 is the same. Further, as seen from the direction of the optical axis of the reflected light, the radius of the hole 31 of the reflection portion 17a is r _1, the radius of the reflected light (which is reflected light just before it is reflected by the reflecting portion 17a) is in r ₂ Suppose there is. Then, in the case of patent document 1, the intensity | strength of a laser beam will be attenuate | damped to (1/2) ² = 1/4 by passing a half mirror twice. On the other hand, in the case of the laser displacement meter 1 according to the present embodiment, since the portion of the hole 31 is not reflected, the intensity of the laser light is attenuated to (r ₂ ² −r ₁ ² ) / r ₂ ^2. become. Therefore,
(R ₂ ² −r ₁ ² ) / r ₂ ² > 1/4 (Formula 1)
If so, the laser displacement meter 1 according to the present embodiment has less attenuation of the laser beam than the case of Patent Document 1. The above (Formula 1) is
r ₁ <(3 ^1/2 / 2) × r ₂ ≈0.866 × r ₂
It becomes. Therefore, even if the diameter of the hole 31 is as large as about 0.8 times the diameter of the reflected light, the attenuation of the laser beam should be less than that of the conventional example using the half mirror. Will be able to.

  As described above, according to the laser displacement meter 1 according to the present embodiment, since a prism or the like is not used in distance measurement using a diffusion laser in which emitted light and reflected light pass through the same optical system, a simple configuration It can be. In addition, when the half mirror is used, the laser beam intensity is attenuated to one-fourth only by passing the laser beam twice through the half mirror. However, in the laser displacement meter 1 according to the present embodiment, Since no half mirror is used, there is no such attenuation. In addition, since the part corresponding to the center area | region of the reflection part 17a is not reflected among reflected light, the light quantity of reflected light will reduce by that much, However, By satisfy | filling the above-mentioned conditions, it is half The attenuation of the laser beam can be suppressed more than when a mirror is used. Thus, since attenuation of the laser beam can be suppressed, the output of the laser beam can be lowered. As a result, the low power laser displacement meter 1 can be provided. Since the laser displacement meter 1 may be driven by a battery in a remote area, it is possible to obtain a merit that a maintenance period can be extended by saving power. Further, since the power of the emitted laser light can be reduced, for example, even when a human or an animal enters the optical path of the emitted light or reflected light, the influence of the laser light can be reduced. become.

  Further, in the laser displacement meter 1 according to the present embodiment, since the emitted light and the reflected light pass through the same optical system, the manufacturing cost can be reduced as compared with the case where both pass through different optical systems. In addition, there is an advantage that the aiming can be facilitated. In addition, the laser displacement meter 1 may be used in a harsh environment of, for example, about −20 ° C. to 50 ° C. In such a case, the member changes in expansion and contraction according to the temperature change. Even so, since the outgoing light and the reflected light pass through the same optical system, the error can be smaller than when they pass through different optical systems.

  In the present embodiment, the case where the reflection unit 17a transmits the light emitted from the light source unit 11 and reflects the reflection light has been described. However, like the laser displacement meter 1 shown in FIG. Instead of 17a, the light emitted from the light source unit 11 is reflected by the light beam diameter changing unit 14 through the central region, and the reflected light from the light beam diameter changing unit 14 is reflected in an outer region that is an outer region of the central region. A reflection part 17b that transmits the light to the light receiving part 16 may be provided. In this case, the laser light emitted from the light source unit 11 is changed in the traveling direction by about 45 degrees in the reflection unit 17b and is incident on the light beam diameter changing unit 14, and the reflected light from the light beam diameter changing unit 14 travels straight. Light is received by the light receiving unit 16. As shown in FIG. 5A, the reflecting portion 17b is composed of a transmitting member 41 such as glass or a highly transparent resin whose outer region transmits the reflected light from the light beam diameter changing portion 14, and has a center. A mirror surface 42 that reflects outgoing light may be provided in the region. Similarly to the mirror surface 32 described above, the mirror surface 42 may be plated on the transmission member 41 or may be attached to the transmission member 41. FIG.5 (b) is sectional drawing which passes along the center of the reflection part 17b shown by Fig.5 (a). Here, it is assumed that the mirror surface 42 which is a highly reflective metal plate is provided on the surface of the transmissive member 41 on the light source unit 11 side (see FIG. 4). Even in this case, the positional relationship among the light source unit 11, the lens 15, and the light receiving unit 16 is different, and is the same as the laser displacement meter 1 except that the reflected light is reflected by the reflecting unit 17 b and the reflected light is transmitted. The description is omitted. Further, the mirror surface 42 may be provided on the surface of the transmissive member 41 opposite to the light source unit 11. Further, as shown in FIG. 5C, the reflection member 17 b does not need to have the transmissive member 41 in the outer region. In that case, the reflection part 17b may be provided with the frame 44 and one or more support parts 45a-45c which support the mirror surface 43 of a center area | region. Each of the support portions 45 a to 45 c is fixed to the frame 44 at least partially. Moreover, since the support parts 45a-45c become an obstruction with respect to reflected light, it is suitable that the cross-sectional area with respect to the optical axis direction of reflected light is as small as possible. 5C shows the case where the reflection portion 17b has three support portions 45a to 45c, this need not be the case. The reflection part 17b may have one support part, may have two support parts, or may have four or more support parts. Even in the reflecting portion 17b shown in FIG. 5C, the emitted light from the light source unit 11 is reflected by the light beam diameter changing unit 14 on the mirror surface 43 in the central region, and the reflected light from the light beam diameter changing unit 14 is reflected. Then, the light passes through the outer region to the light receiving unit 16. The mirror surfaces 42 and 43 may be elliptical, and the outer shape of the transmissive member 41 and the frame 44 may be elliptical as in the case of the reflective portion 17a.

  In addition, when the laser displacement meter 1 according to the present embodiment measures the distance using the reflecting portion 17a or the reflecting portion 17b, the size of the central region through which the laser beam is transmitted in the reflecting portion 17a or the reflecting portion 17b. The size of the central region where the laser beam is reflected is preferably smaller. Therefore, the size of the central region may be the smallest size in a range in which the laser light emitted from the light source unit 11 does not hit the mirror surfaces 32 and 33 or deviate from the mirror surfaces 42 and 43. It is preferable that the laser beam does not hit the mirror surfaces 32 and 33 or deviate from the mirror surfaces 42 and 43 even if the error is deviated. In the case of the laser displacement meter 1 shown in FIGS. 4 and 5, the mirror surfaces 42 and 43 may be smaller than the laser light. Even in that case, only a part of the laser light emitted from the light source unit 11 is not incident on the light beam diameter changing unit 14, and the distance measurement is not seriously adversely affected.

  In the present embodiment, when the calculation unit 18 measures the time Δt from when the laser beam is emitted to when it is received, the laser displacement meter 1 is As shown in FIG. 6, a half mirror 51 that reflects a part of the emitted light and an emitted light receiving unit 52 that receives the emitted light reflected by the half mirror 51 may be further provided. Then, the calculation unit 18 corrects the timing at which the outgoing light receiving unit 52 receives the outgoing light or the timing corrected by the time until the laser light reaches the outgoing light receiving unit 52 from the light source unit 11. May be used to measure the time Δt. Needless to say, the laser displacement meter 1 shown in FIG. 4 may include the half mirror 51 and the light receiving portion 52 for outgoing light. In addition, the measurement of the time Δt using the light receiving portion 52 for outgoing light is already known and will not be described in detail.

Moreover, in this Embodiment, the light beam diameter change part 14 may vary the magnification regarding emitted light or reflected light using an annular lens. Here, the annular lens is a lens in which two lenses having different focal lengths are formed concentrically. In this case, as shown in Figure 7, a lens 12 having a beam diameter changing unit 14, the divergence having a center focal length is -f _11, and an outer peripheral portion is the focal length is -f ₂₁ It is a lens. The lens 13 having the beam diameter changing portion 14 is a converging lens having a center focal length is f _12, and an outer peripheral portion is the focal length is f _22. In addition, by making the focal point of the central part of the lenses 12 and 13 coincide with the position F ₁ in FIG. 7, the light beam diameter changing unit 14 expands the emitted light that is parallel light to parallel light. Further, the focal point of the outer peripheral portion of the lens 12 and 13, by matching the position F ₂ in FIG. 7, the beam diameter changing unit 14 will be converged to a parallel light reflected light into parallel light. Here, the light beam diameter of the outgoing light incident on the light beam diameter changing unit 14 is d ₁ , the light beam diameter of the outgoing light emitted from the light beam diameter changing unit 14 is d ₂ , and the light enters the light beam diameter changing unit 14. When the light beam diameter of the reflected light is d ₃ and the light beam diameter of the reflected light emitted from the light beam diameter changing unit 14 is d ₄ , the magnification of the emitted light to be enlarged and the magnification of the reflected light to be reduced are as follows: become that way. The magnification of the emitted light to be enlarged is the magnification of the light beam diameter using the central portion of the lenses 12 and 13, and the magnification of the reflected light to be reduced is the light beam diameter of the outer periphery of the lenses 12 and 13. Magnification. These magnifications are magnifications when viewed from the lens 12 side. Therefore, the reduction rate of the luminous flux diameter of the reflected light is the reciprocal of the magnification of the reflected light.
Magnification of the expanded outgoing light M ₁ = f ₁₂ / f ₁₁ = d ₂ / d ₁
Magnification factor of reflected light to be reduced M ₂ = f ₂₂ / f ₂₁ = d ₃ / d ₄

The lens so that the magnification M _{1 of the} emitted light, that is, the magnification using the central portions of the lenses 12 and 13 is larger than the magnification M _{2 of the} reflected light, that is, the magnification using the outer peripheral portions of the lenses 12 and 13. By designing and arranging 12 and 13, the outgoing light is expanded so that the beam diameter becomes larger, and the reflected light is not so converged as compared with the expansion. Therefore, it is possible to increase the ratio of reflection by the reflecting portion 17a, and it is possible to further reduce the attenuation of the laser beam. Here, if the ratio of the reflected light lost by passing through the hole 31 is calculated,
d ₁ ² / d ₄ ² = (d ₂ / M ₁ ) ² / (d ₃ / M ₂ ) ²
= (M ₂ / M ₁ ) ² × (d ₂ / d ₃ ) ²
It becomes. However, the diameter as viewed from the optical axis of the holes 31 are close to be d _1. From the above equation, it can be seen that the greater the magnification M _{1 of the} emitted light is greater than the magnification M _{2 of} the reflected light, the smaller the proportion of the reflected light lost in the holes 31. Further, the larger the effective optical aperture (d ₃ ) of the light beam diameter changing unit 14 where the reflected light is incident relative to the diameter (d ₂ ) of the outgoing light emitted from the light beam diameter changing unit 14, the more the reflected light is transmitted through the hole 31. It can be seen that the rate of loss is reduced. Specifically, M ₁ = M ₂ , and the optical effective aperture (d ₃ ) of the light beam diameter changing unit 14 where the reflected light is incident is equal to the diameter (d ₂ ) of the outgoing light emitted from the light beam diameter changing unit 14. If it is twice or more, the rate at which the reflected light is lost in the holes 31 is ¼ or less. Therefore, in that case, the loss ratio of the received light amount can be remarkably reduced from the loss ratio “3/4” of the received light amount in the conventional example using the half mirror. When (M ₂ / M ₁ ) is less than 1, the loss of received light amount is further reduced. The emitted light that has passed through the center of the lens 12 (region where the focal length is −f ₁₁ ) passes through the center of the lens 13 (region where the focal length is f ₁₂ ), and the outer periphery of the lens 13 (focal length). There the reflected light passing through the region) of f ₂₂ is an outer peripheral portion of the lens 12 (as the focal length to pass through the region) of -f _21, lenses 12 and 13 are designed, it is preferable to be disposed. Moreover, although the case where the reflection part 17a was used was demonstrated in FIG. 7, it is the same also in the case of the reflection part 17b.

  Moreover, although the case where the light receiving unit 16 is a photodiode or the like has been described in the present embodiment, this need not be the case. The light receiving unit 16 may be an image sensor such as a CCD or a CMOS. In that case, the light receiving unit 16 can acquire not only the amount of received light but also a received light image. Therefore, for example, it may be possible to finely adjust the angle of the optical system or to perform finer light reception using the received light image.

  In the present embodiment, the case where the lenses and the like face each other has been described, but this need not be the case. The positions where the outgoing light and the reflected light pass may be slightly shifted by tilting each lens little by little. In addition, such a thing is performed conventionally, The detailed description is abbreviate | omitted.

  In the laser displacement meter 1 according to the present embodiment, a small amount of reflected light is transmitted or reflected toward the light source unit 11. Accordingly, an optical isolator is further provided between the light source unit 11 and the reflection units 17a and 17b, so that only the laser light emitted from the light source unit 11 reaches the reflection units 17a and 17b, and is reflected from the reflection units 17a and 17b. Laser light that is reflected light may not reach the light source unit 11. The optical isolator may be, for example, a polarization dependent type or a polarization independent type.

  1, 4, and 6 according to the present embodiment, the reflection portions 17 a and 17 b are provided so as to have an angle of about 45 degrees with respect to the optical path of the laser light emitted from the light source portion 11. Although it is shown about the case where it exists, it may not be so. Even if the reflecting portions 17a and 17b have an angle other than about 45 degrees with respect to the optical path of the laser light emitted from the light source portion 11, the lens 15 and the light receiving portion 16 or the light source portion 11 accordingly. It is possible to realize a laser displacement meter 1 similar to that described above by appropriately arranging.

  Further, in the present embodiment, the case where the laser displacement meter 1 includes the lens 15 for focusing on the light receiving unit 16 has been described, but this need not be the case. For example, when the mirror surfaces 32 and 33 of the reflecting part 17a are concave mirrors and can be condensed on the light receiving part 16, or when the transmissive member 41 of the reflecting part 17b is a convex lens and can be condensed on the light receiving part 16, Alternatively, when the light receiving unit 16 can receive a wide range of laser light, the laser displacement meter 1 may not include the lens 15.

  Moreover, although the case where the average of the distances repeatedly calculated by the calculation unit 18 has been described in the present embodiment, this need not be the case. The calculation unit 18 may calculate the distance calculated once as the distance to the reflection unit 30 instead of calculating the average of the distances.

  In the above embodiment, each process or each function may be realized by centralized processing by a single device or a single system, or may be distributedly processed by a plurality of devices or a plurality of systems. It may be realized by doing.

  In the above embodiment, the information exchange between the components is performed by one component when, for example, the two components that exchange the information are physically different from each other. It may be performed by outputting information and receiving information by the other component, or when two components that exchange information are physically the same, one component May be performed by moving from the phase of the process corresponding to to the phase of the process corresponding to the other component.

  In the above embodiment, information related to processing executed by each component, for example, information received, acquired, or calculated by each component, and threshold value used by each component in the process Information such as formulas, addresses, and the like may be stored temporarily or for a long time in a recording medium (not shown) even when not specified in the above description. Further, the storage of information in the recording medium (not shown) may be performed by each component or a storage unit (not shown). Further, reading of information from the recording medium (not shown) may be performed by each component or a reading unit (not shown).

  In the above embodiment, when information used by each component, for example, information such as a threshold value, an address, and various setting values used by each component may be changed by the user Even if it is not specified in the above description, the user may be able to change the information as appropriate, or it may not be. If the information can be changed by the user, the change is realized by, for example, a not-shown receiving unit that receives a change instruction from the user and a changing unit (not shown) that changes the information in accordance with the change instruction. May be. The change instruction received by the receiving unit (not shown) may be received from an input device, information received via a communication line, or information read from a predetermined recording medium, for example. .

  In the above embodiment, when two or more components included in the laser displacement meter 1 include a communication device or an input device, the two or more components may physically include a single device. Or you may have separate devices.

  In the above embodiment, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

  Further, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

  As described above, according to the laser displacement meter of the present invention, it is possible to obtain an effect that the measurement of the distance with a small attenuation of the laser beam can be realized with a simple configuration. For example, by measuring the distance to the reflecting means, This is useful as a device for monitoring fluctuations.

DESCRIPTION OF SYMBOLS 1 Laser displacement meter 11 Light source part 12, 13, 15 Lens 14 Light beam diameter change part 16 Light-receiving part 17a, 17b Reflection part 18 Calculation part 19 Accumulation part 20 Storage part 21 Displacement detection part 22 Displacement output part 30 Reflection means 51 Half mirror 52 Receiver for outgoing light

Claims (6)

A light source that emits laser light;
A light beam diameter changing unit that expands a light beam diameter of the emitted light that is laser light emitted from the light source unit, and collects the reflected light that is reflected by the reflecting means of the emitted light after the expansion;
A light receiving unit for receiving the reflected light;
A calculation unit that calculates a distance to the reflection unit using the emitted light and the reflected light;
An accumulation unit for accumulating the distance calculated by the calculation unit;
Using a distance accumulated by the accumulator, a displacement detector for detecting a displacement of the distance to the reflecting means;
A displacement output unit for performing an output related to the displacement detected by the displacement detection unit;
By transmitting one of the unextended outgoing light emitted from the light source unit and the reflected light from the light beam diameter changing unit and reflecting the other, the outgoing light from the light source unit is passed through the central region. A reflecting unit that transmits or reflects the light beam diameter changing unit and reflects or transmits the reflected light from the light beam diameter changing unit to the light receiving unit through an outer region that is an outer region of the central region. Prepared,
The light beam diameter changing unit is a laser displacement meter in which an effective aperture for the reflected light is larger than a light beam diameter of the emitted light. The luminous flux diameter changing part is
A diverging lens for diverging outgoing light before expansion;
A converging lens that converges outgoing light that has passed through the diverging lens, and
The diverging lens and the converging lens are annular lenses in which two lenses having different focal lengths are formed concentrically,
The laser displacement meter according to claim 1, wherein a magnification using a central portion of the diverging lens and the converging lens is larger than a magnification using an outer peripheral portion of the diverging lens and the converging lens. The reflecting unit transmits the light emitted from the light source unit to the light beam diameter changing unit through the central region, and the reflected light from the light beam diameter changing unit to the light receiving unit through the outer region. The laser displacement meter according to claim 1, wherein the laser displacement meter is reflected. The laser displacement meter according to claim 3, wherein the reflecting portion has a hole through which the emitted light passes in the central region, and a mirror surface is provided in the outer region. The reflection unit reflects light emitted from the light source unit to the light beam diameter changing unit through the central region, and reflects light from the light beam diameter changing unit to the light receiving unit through the outer region. The laser displacement meter according to claim 1, wherein the laser displacement meter is transmitted. 6. The laser according to claim 5, wherein the reflecting portion is provided with a mirror surface that reflects the emitted light in the central region, and the outer region is configured by a transmission member that transmits the reflected light from the light beam diameter changing portion. Displacement meter.

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