JP6198399B2 - Light wave distance meter - Google Patents

Description

  The present invention relates to a light wave distance meter that includes a light receiving optical system that receives measurement light reflected by a measurement object and an emission optical system that irradiates the measurement object with measurement light, and measures a distance to a target.

  The above-mentioned optical distance meter irradiates the object to be measured with modulated measurement light in a predetermined wavelength region, receives the reflected light from the object to be measured, and measures from the phase difference between the internal reference light and the received measurement light. Measure the distance to the object.

  In such a lightwave distance meter, in order to measure the phase difference between the internal reference light and the measurement light, the light amount (signal) level is adjusted in advance to the same measurement light as the measurement light that received the internal reference light. The light amount is adjusted by using a film having a density gradient, using a filter, and setting the appropriate density position on the density film.

  In Patent Document 1 and Patent Document 2, measurement light is irradiated to a measurement object, measurement light reflected by the measurement object is received, and the received measurement light and an internal reference light whose light quantity is adjusted by a density filter are disclosed. And a lightwave distance meter that measures the distance to the object to be measured.

See JP 2004-144681 A See JP 2008-76212 A

  However, when a density type filter with a printing type with ink on the emulsion surface is used, deterioration such as ink peeling will occur if a mechanical load is applied to the emulsion surface, such as touching the density filter fixing tool. May occur, and the density of the density filter itself may change. In addition, if unevenness occurs in the emulsifier, the incident measurement light is diffusely reflected, which causes stray light (optical noise) inside the optical system, resulting in a decrease in S / N of the measurement light signal and a decrease in measurement accuracy. Resulting in.

  Further, in the conventional optical distance meter, when the density filter is fixed with a screw or the like at the center of rotation, the intensity of the measurement light may change. This is because when the density of the density filter is adjusted, the density position of the density filter is rotated when the density filter is tightened with a fixing screw or the like at a position where the measurement light has a predetermined intensity.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a lightwave distance meter that can prevent the density filter from being scratched and can reliably fix the density filter position setting. .

In order to solve the above-mentioned problem, the invention according to claim 1, the reflected light from the measurement object obtained by irradiating the measurement object with the measurement light acquired from the light source, the transmission light acquired from the light source and transmitted In the optical wave distance meter that measures the distance to the object to be measured based on the internal reference light attenuated in accordance with the amount of the reflected light received by the density filter having a variable light quantity, the density filter includes a circumferential A disk-shaped density gradient film having a density gradient in the direction, and at least one disk-shaped protective film having a uniform density arranged on the density gradient film without being bonded to the density gradient film. It is characterized by that.

  Similarly, the invention according to claim 2 is the lightwave distance meter according to claim 1, wherein the density gradient film and the protective film are independently rotatable.

Similarly, the invention according to claim 3 is the lightwave distance meter according to claim 1 or 2, wherein the surface of the protective film is subjected to irregular reflection prevention processing.

  According to the lightwave distance meter according to the present invention, it is possible to prevent the density filter from being damaged and to reliably fix the position of the density filter whose density is set.

It is a front view which shows the light wave distance meter which concerns on embodiment of this invention. It is sectional drawing which similarly shows a light wave rangefinder. FIG. 2 also shows an optical system of the optical distance meter, where (a) is a schematic diagram showing a state of measurement light emission, and (b) is a schematic diagram showing a state of internal reference light emission. It is a perspective view which similarly shows the optical wave distance meter internal structure. It is a disassembled perspective view which similarly shows the structure of the density filter of a light wave distance meter. It is a disassembled perspective view which similarly shows the structure of the density filter of a light wave distance meter.

  An optical distance meter according to an embodiment for carrying out the present invention will be described. FIG. 1 is a front view showing a light wave distance meter according to an embodiment of the present invention, FIG. 2 is a sectional view showing the light wave distance meter, and FIG. 3 is a view showing an optical system of the light wave distance meter. Is a schematic diagram showing a state of measurement light emission, and (b) is a schematic diagram showing a state of internal reference light emission.

  As shown in FIG. 1, the optical distance meter 100 according to the embodiment includes a base 102 provided on a base 101 attached to a tripod (not shown), and a telescope 103 including an optical system is provided on the base 102. It is supported. The base 101 has leveling screws 104 and can be leveled so that the pedestal 102 is horizontal. The gantry 102 can rotate around a vertical axis, and the telescope unit 103 can rotate around a horizontal axis. Further, the gantry 102 is provided with an operation input unit 107 having a display unit 106, and the display unit 106 displays a measured value of a distance to a measurement object and the like.

  An optical system of the lightwave distance meter 100 according to the embodiment will be described. FIG. 2 is a cross-sectional view showing the light wave distance meter, FIG. 3 is a view showing the optical system of the light wave distance meter, FIG. 2A is a schematic view showing the state of measurement light emission, and FIG. It is a schematic diagram which shows this state. In the optical distance meter 100, a lens barrel 120 and a base portion 130 are formed in a housing 110. As shown in FIG. 2, the optical distance meter 100 includes, as an optical system 200, an objective lens system 210 that is a light receiving optical system, an emission optical system 220 that emits measurement light, and measurement light from the objective lens system 210. And an exit reflection optical system 240 that guides the light to the optical fiber 260. The optical system 200 includes a light receiving / reflecting optical system 250 and a collimating optical system 270. The optical fiber 260 guides the measurement light to the optical sensor 261 (see FIG. 3). The collimating optical system 270 is used to determine and correct the direction of the lightwave distance meter 100 so that the object image from the objective lens system 210 can be viewed.

  The objective lens system 210 is disposed in the lens barrel 120 and includes a first optical axis O1 directed to the prism 280 that is the object to be measured, and condenses light from the object to be measured. The objective lens system 210 includes three lenses, and various aberrations are corrected to provide a positive power as a whole. The emission optical system 220 is disposed on the base unit 130, includes a second optical axis O2 parallel to the first optical axis O1, and emits light from the light source 230 as measurement light that is parallel light. The light source 230 is, for example, a laser diode that generates infrared rays. The emission optical system 220 includes a collimator lens 221, a chopper 226 provided with a trapezoidal prism 225 that intermittently blocks the emitted light and extracts the emitted light as internal reference light, and a circular that is controlled by a microcomputer or the like to adjust the amount of external luminous flux. 222, a density filter 310 that adjusts the amount of internal reference light by manually setting the rotational position, and a diaphragm 224. The density filter 310 is a disk-shaped member having a density gradient on the circumference. The circular 222 is a disk-like member that includes a density filter having a density gradient on the circumference for adjusting the measurement light emission light amount and is rotationally driven by a circular drive motor 223.

  Further, the chopper 226 is rotationally driven by a chopper drive motor 227, and is driven so as to appear at the front side of the collimator lens 221 on the second optical axis O2 at a predetermined timing. Here, the chopper 226 is formed with a plate portion 226 a that covers the collimator lens 221. The trapezoidal prism 225 includes two reflecting surfaces 225a and 225b as shown in FIGS. 3A and 3B, and guides the internal reference light to the internal reference light sensor 290.

  When the measurement light is emitted, as shown in FIG. 3A, the chopper 226 is detached from the emission port of the collimator lens 221, and the light from the light source 230 is directed to the mirror member 241 while being interrupted by the circular 222 intermittently. Injected. In FIG. 3A, the optical axis of the internal reference light is indicated by a one-dot chain line, and the optical path of the measurement light is indicated by a solid line with an arrow. In the state shown in FIG. 3A, the internal reference light is not generated.

  When the internal reference light is emitted, as shown in FIG. 3B, the chopper 226 is in a state where the reflecting surface 225 a of the trapezoidal prism 225 is disposed at the exit of the collimator lens 221. In this state, the light from the light source 230 passes through the collimator lens 221, is reflected by the reflecting surfaces 225 a and 225 b of the trapezoidal prism 225, and is emitted toward the density filter 310. The internal reference light whose density has been adjusted by the density filter 310 enters the optical fiber 263. At this time, since the opening of the collimator lens 221 is completely covered with the plate portion 226a, no light is incident on the objective lens system 210 side. The optical fiber 263 merges with the optical fiber 260, and the internal reference light from the optical fiber 263 and the measurement light from the optical fiber 260 are detected by the same optical sensor 261. In FIG. 3B, the optical path of the internal reference light is indicated by a solid line with an arrow, and the optical axis of the measurement light is indicated by an alternate long and short dash line. In the state shown in FIG. 3B, no measurement light is generated.

  The exit reflection optical system 240 includes a mirror member 241 that is a first reflection unit having a reflection surface formed obliquely on the second optical axis O2, and a second reflection unit that is disposed on the incident side (outside) of the objective lens system 210. And a light transmitting / reflecting prism 242. The light transmitting / reflecting prism 242 includes a reflecting surface 242a inclined on the first optical axis O1. In this example, a cover glass 281, which is a plane parallel glass, is disposed outside the objective lens system 210, and the light transmitting / reflecting prism 242 is disposed on the inside of the cover glass 281.

  The light receiving / reflecting optical system 250 includes a dichroic mirror 251 and a light receiving / reflecting prism 252 which is a light receiving / reflecting member that reflects light from the dichroic mirror 251 in a perpendicular direction. The dichroic mirror 251 is disposed in the lens barrel 120 and reflects measurement light, which is light in a predetermined wavelength band, among light incident from the objective lens system 210 along the first optical axis O1. Light in other bands is transmitted and enters the collimating optical system 270 disposed in the lens barrel 120. An operator of the optical distance meter 100 can collimate using the collimation optical system 270. The light receiving / reflecting prism 252 has a reflecting surface 252a formed at an angle of 45 degrees on the first optical axis O1, and reflects the light from the dichroic mirror 251 toward the optical fiber 260.

  In such an optical wave distance meter 100, the distance to the prism 280, which is a measurement object, is measured based on the measurement light from the prism 280, which is the measurement object detected by the optical sensor 261, and the internal reference light from the optical fiber 263. Calculate.

  Next, the density filter 310 will be described. FIG. 4 is a perspective view showing the internal structure of the light wave distance meter according to the embodiment of the present invention, FIG. 5 is an exploded perspective view showing the structure of the density filter of the light wave distance meter, and FIG. 6 is the structure of the density filter of the light wave distance meter. FIG. As shown in FIGS. 4 and 5, the density filter 310 includes a density gradient film 311 having a density gradient and a protective film 312 having a constant density, for example, and a fixing screw 313 disposed on the telescope unit 103. The density filter mounting portion 131 of the base portion 130 is disposed. The density gradient film 311 and the protective film 312 are made of a synthetic resin film. And even if the protective film 312 rotates, the density gradient film 311 is attached without joining so that it does not rotate with the protective film 312. 4 does not show the chopper 226, and FIGS. 5 and 6 do not show the circular 222 and the chopper 226.

  When adjusting the amount of the internal reference light, the entire density filter 310 is rotated while the density gradient film 311 and the protective film 312 are overlapped. Then, the light quantity is determined by stopping at an appropriate position. Then, when fixing the position of the density filter 310, the fixing screw 313 is rotated and fixed in the tightening direction. At this time, even if the protective film 312 rotates due to the rotation of the fixing screw 313, the density gradient film 311 does not rotate. For this reason, when the density filter 310 is fixed, the signal intensity of the internal reference light does not change. Further, it is possible to prevent the tool used for turning the fixing screw 313, for example, the tip of a driver, from coming into direct contact with the density gradient film 311. For this reason, the surface of the density filter 310 is not damaged. This adjustment is performed at the time of adjustment at the manufacturing plant as in the conventional example. The adjustment work is performed by removing the upper cover of the housing 110. When the upper cover is removed, the fixing screw 313 is exposed and can be operated with a tool such as a screwdriver.

  Furthermore, even if the protective film 312 is damaged for some reason, it is only necessary to replace the protective film 312, which is not costly and easy to replace.

  Thus, since the protective film 312 covers the emulsion surface of the density gradient film 311 manufactured in the printing process, unnecessary scattering in the unevenness of the emulsion surface of the density gradient film 311 can be avoided. For this reason, unnecessary stray light is not generated inside the light receiving optical system, which contributes to a reduction in measurement error.

  Further, when the surface of the protective film 312 is subjected to irregular reflection prevention processing, incident light is not irregularly reflected, scattering of internal reference light can be prevented, and measurement accuracy can be improved. As the irregular reflection prevention processing, mirror surface treatment of the surface of the protective film, AR coating, and the like are performed.

DESCRIPTION OF SYMBOLS 100: Light wave rangefinder 101: Base part 102: Mount 103: Telescope part 104: Leveling screw 106: Display part 107: Operation input part 110: Case 120: Lens barrel 130: Base part 131: Density filter attaching part 200 : Optical system 210: Objective lens system 211: Laser light source 220: Emission optical system 221: Collimator lens 222: Circular 223: Circular drive motor 224: Aperture 225: Trapezoidal prism 225 a, 225 b: Reflecting surface 226: Chopper 227: Chopper drive motor 230: Light source 240: Emission reflection optical system 241: Mirror member 242: Light transmission reflection prism 242a: Reflection surface 250: Light reception reflection optical system 251: Dichroic mirror 252: Light reception reflection prism 252a: Reflection surface 260: Optical fiber (outgoing (outside ) For optical path)
261: Optical sensor 263: Optical fiber (for internal reference optical path)
270: collimating optical system 280: prism 281: cover glass 290: internal reference light sensor 310: density filter 311: density gradient film 312: protective film 313: fixing screw O1: first optical axis O2: second optical axis

Claims (3)

Reflected light from the measurement object obtained by irradiating the measurement object with the measurement light acquired from the light source;
In the lightwave distance meter that measures the distance to the object to be measured based on the internal reference light that is acquired from the light source and attenuated in accordance with the amount of the reflected light that is received by the density filter with a variable amount of transmitted light,
The density filter includes a disk-shaped density gradient film having a density gradient in a circumferential direction, and at least one uniform density circle disposed on the density gradient film without being bonded to the density gradient film. A light wave distance meter comprising a plate-like protective film.   The light wave distance meter according to claim 1, wherein the density gradient film and the protective film are independently rotatable. Light wave rangefinder according to claim 1 or claim 2, characterized in that diffused reflection preventing process on the surface of the protective film is applied.