JP2014149171A - Light-wave range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce measurement noise caused by stray light due to light emission from measurement light itself, and to eliminate the necessity of use of an expensive prism that is difficult to be manufactured.SOLUTION: A light-wave range finder comprises: an objective lens system 110 for receiving light from a measured object; an emission optical system 120 for emitting light from a light source 130, generating light having a predetermined wavelength region, as measurement light that is parallel light; an emission reflection optical system 140 in which the measurement light is reflected and emitted to the measured object; and a light receiving reflection optical system 150 for reflecting the measurement light received in the objective lens system 110 toward an optical fiber 160. The emission reflection optical system 140 includes a mirror member 141 and a light transmitting reflection prism 142. The light receiving reflection optical system 150 includes a dichroic mirror 151 and a light receiving reflection prism 152 disposed on the emission side of the objective lens system 110.

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-described 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 calculates the phase difference between the irradiated measurement light and the reflected measurement light. Measure the distance to the measurement object.

  Examples of such light wave distance meters include the following. FIG. 3 is a sectional view showing an optical system of a conventional optical distance meter. The light wave distance meter 300 includes an objective lens 310, a prism 320 having two reflecting surfaces, a light source 330, an emission optical system 340, a reflecting mirror 350, a dichroic mirror 360, a collimating optical system 370, and a light receiving device. An element 380.

  The objective lens 310 is composed of three lenses arranged on the optical axis Oa. The prism 320 is disposed on the optical axis Oa behind the objective lens 310 and has two parallel reflecting surfaces that form an angle of 45 degrees with respect to the optical axis Oa, that is, an emitting reflecting surface that reflects in the direction in which the measuring light is emitted. 321 and a light receiving reflection surface 322 that reflects incident measurement light toward the light receiving element 380.

  The light source 330 generates light in a predetermined wavelength region. The emission optical system 340 includes a collimator 341 that is arranged on an optical axis Ob parallel to the optical axis Oa and that converts light from the light source 330 into parallel light, and an optical chopper 342 that intermittently blocks measurement light. The reflecting mirror 350 is disposed at an angle of 45 degrees with respect to the optical axis Ob, changes the direction of the measuring light from the emission optical system 340 by 90 degrees, and is directed toward the reflecting surface 321 for emission of the prism 320 along the optical axis Oc. Reflects the measurement light. The measurement light reflected by the emission reflecting surface 321 is emitted to the measurement object through the objective lens 310.

  The reflected light from the measurement object reaches the dichroic mirror 360 through the objective lens 310. The dichroic mirror 360 reflects measurement light in a predetermined wavelength band from incident light, transmits other light, and emits it to the collimating optical system 370. The measurement light reflected by the dichroic mirror 360 is reflected by the light receiving reflection surface 322 of the prism 320 and enters the light receiving element 380.

  Such an optical distance meter 300 requires two reflecting surfaces in order to emit measurement light from the emission optical system 340 toward the measurement object, and to enter the light receiving element 380 with measurement light reflected by the measurement object. . Conventionally, in this lightwave distance meter, a prism having two reflecting surfaces is arranged to reduce the number of parts, and this is arranged on the back side of the objective lens 310. Optical wave distance meters having the same configuration are described in Patent Document 1 and Patent Document 2.

See JP-A-4-319687 See Special Table 2002-525582

  However, when the prism 320 having the emission reflecting surface 321 and the light receiving reflection surface 322 is disposed on the back surface of the objective lens unit as in the conventional lightwave distance meter 300, when the measurement light is emitted, Depending on the curvature or the like, part of the measurement light may be reflected on the light receiving side (dichroic mirror 360 side) and detected by the light receiving element 380, resulting in noise. This significantly hinders the measurement accuracy of the lightwave distance meter and results in narrowing the measurement range.

  Further, if two reflecting surfaces are formed on one prism 320, adjusting the prism 320 at the time of adjusting the optical axis causes the optical axis to move on both the light transmitting side and the light receiving side, so the tolerance of the prism 320 is extremely small. This makes it difficult to manufacture the prism 320 and increases the price.

  The present invention has been made in view of the above-described problems, and provides a lightwave distance meter that reduces measurement noise caused by stray light due to emission of measurement light itself and does not require the use of an expensive prism that is difficult to manufacture. For the purpose.

  The invention according to claim 1, which solves the above-described problem, includes a first optical axis that faces the object to be measured, an objective lens system that receives light from the object to be measured, and second light that is parallel to the first optical axis. An emission optical system that emits light from a light source that generates light in a predetermined wavelength region as measurement light that is parallel light, and reflects the measurement light from the emission optical system to the first optical axis. And an exit reflection optical system that emits toward the object to be measured, and the measurement light reflected by the object to be measured and received by the objective lens system is disposed at a position away from the first optical axis. A light receiving and reflecting optical system that reflects toward the light receiving means, wherein the objective reflecting optical system guides the measurement light to an incident side position of the objective lens system on the first optical axis, And the measurement light is arranged on the incident side of the objective lens system. A second reflecting means for reflecting toward the object to be measured along an axis, wherein the light-receiving / reflecting optical system is disposed on an exit side of the objective lens system, and is collected from the measurement object condensed by the objective lens system. An optical distance meter comprising an object reflecting means for reflecting the reflected light of the measuring light from the first optical axis toward the light receiving means.

  Similarly, the invention according to claim 2 is characterized in that, in the lightwave distance meter according to claim 1, the objective reflection optical system and the light receiving reflection optical system can be individually adjusted.

  Similarly, the invention according to claim 3 is the lightwave distance meter according to claim 1 or 2, wherein a parallel plate transparent body is disposed on the incident side of the objective lens system, and the second reflecting means includes It is bonded to the side surface of the objective lens system of a transparent body.

  Similarly, the invention according to claim 4 is the optical wave distance meter according to any one of claims 1 to 3, wherein the light receiving means is an optical cable in which a light receiving surface is disposed toward the first optical axis. It is characterized by being.

  Similarly, according to a fifth aspect of the present invention, in the light wave distance meter according to any one of the first to fourth aspects, the light receiving / reflecting optical system is configured to apply only the predetermined wavelength region to the light receiving / reflecting means. A dichroic mirror for reflection is provided.

  Similarly, the invention according to claim 6 is the collimating optical system for enlarging and displaying the image from the objective lens system in the lightwave distance meter according to any one of claims 1 to 5. It is characterized by providing.

  Similarly, the invention according to claim 7 is the lightwave distance meter according to any one of claims 1 to 6, further comprising modulation means for modulating the measurement light.

  According to the lightwave distance meter of the present invention, since the second reflecting means of the emission optical system is arranged on the incident side (outside) of the objective lens, the reflection by the objective lens does not enter the inside of the apparatus and is detected as noise. It will not be. Further, the second reflecting means of the exit reflecting optical system that reflects the measurement light toward the object to be measured is disposed on the incident side of the objective lens, and the objective reflecting means is disposed on the exit side of the objective lens separately from the second reflecting means. Since it is arranged, the optical axis can be adjusted independently, so that the manufacturing of each member does not require so high accuracy and can be manufactured at low cost. Furthermore, it becomes easy to adjust the optical axis of each part, and it is difficult to cause troubles in adjustment in addition to shortening the time required for the adjustment work. In the maintenance, only necessary portions can be replaced, so that the working time can be shortened and the repair cost can be reduced.

It is a section perspective view showing the whole lightwave distance meter structure concerning an embodiment of the present invention. It is sectional drawing which similarly shows a light wave rangefinder. It is sectional drawing which shows the optical system of the conventional lightwave distance meter.

  An optical distance meter according to an embodiment for carrying out the present invention will be described. FIG. 1 is a cross-sectional perspective view showing the overall structure of a lightwave distance meter according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a lightwave distance meter according to the embodiment of the present invention.

  As shown in FIG. 1, the optical distance meter 100 includes a housing 103 and a lens barrel 103 and a base portion 102 formed therein. As shown in FIG. 2, the optical distance meter 100 includes an objective lens system 110 that is a light receiving optical system, an emission optical system 120 that emits measurement light, and measurement light from the objective lens system 110 to an optical fiber 160. And an exit reflection optical system 140 for guiding the light. The lightwave distance meter 100 includes a light receiving / reflecting optical system 150 and a collimating optical system 170. The optical fiber 160 guides measurement light to an optical sensor (not shown). The collimating optical system 170 is used to determine or correct the direction of the lightwave distance meter 100 so that the object image from the objective lens system 110 can be viewed.

  The objective lens system 110 is disposed in the lens barrel 103 and includes a first optical axis O1 that faces the object to be measured, and condenses light from the object to be measured. The objective lens system 110 includes three lenses, and various aberrations are corrected to provide a positive power as a whole. The emission optical system 120 is disposed on the base unit 102, includes a second optical axis O2 parallel to the first optical axis O1, and emits light from the light source 130 and measurement light that is parallel light from the light source 130. The light source 130 is, for example, a laser diode that generates infrared rays. The emission optical system 120 includes a collimator lens 121, a light chopper 122 that is a modulation means for modulating the emission light, a density filter 123, and a diaphragm 124. The density filter 123 attenuates reference light extracted from the light source 130 by a trapezoidal prism (not shown), and is a disk-shaped member having a density gradient on the circumference. The optical chopper 122 is a disk-shaped opaque member that includes a cutout portion for transmitting measurement light and is driven to rotate.

  The exit reflection optical system 140 includes a mirror member 141 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 110. And a light transmission / reflection prism 142. The light transmitting / reflecting prism 142 includes a reflecting surface 142a inclined on the first optical axis O1. In this example, a cover glass 181, which is a plane parallel glass, is disposed outside the objective lens system 110, and the light transmitting / reflecting prism 142 is disposed by being adhered to the inside of the cover glass 181.

  The light receiving / reflecting optical system 150 includes a dichroic mirror 151 and a light receiving / reflecting prism 152 that is a light receiving / reflecting agent that reflects light from the dichroic mirror 151 in a right angle direction. The dichroic mirror 151 is disposed in the lens barrel 103 and reflects measurement light, which is light in a predetermined wavelength band, out of light incident along the first optical axis O1 from the objective lens system 110. Light in other bands is transmitted and enters the collimating optical system 170 disposed in the lens barrel 103. An operator of the optical distance meter 100 can collimate using the collimation optical system 170. The light receiving / reflecting prism 152 has a reflecting surface 152a formed at an angle of 45 degrees with respect to the first optical axis O1, and reflects light from the dichroic mirror 151 toward the optical fiber 160.

  In the optical distance meter 100, the optical axis of the measurement light is first adjusted by a cover glass 181 to which a light transmission / reflection prism 142 is attached, and then adjusted in detail by a mirror member 141. At this time, the cover glass 181 is parallel plane glass, and has no curvature on the front and back surfaces. For this reason, the measurement light is not easily mixed into the apparatus and does not become stray light (optical noise). Therefore, high-accuracy signal measurement is possible, which contributes to improving the measurement accuracy of the machine body.

  The optical axis of the light receiving / reflecting optical system 150 is adjusted by the dichroic mirror 151 and the light receiving / reflecting prism 152. Thus, the exit reflection optical system 140 and the light reception reflection optical system 150 can be adjusted independently. For this reason, even when the optical axis of the measurement light moves for some reason during the measurement, only the exit reflection optical system 140 can be readjusted independently. At that time, readjustment of the light receiving / reflecting prism 152 on the light receiving / reflecting optical system 150 side is basically unnecessary.

  According to the lightwave distance meter 100 according to the present embodiment, since the exit reflection optical system 140 and the light reception reflection optical system 150 are independent and arranged with the objective lens system 110 interposed therebetween, it is easy to manufacture parts. In addition, each optical axis can be easily adjusted. Furthermore, it is possible to contribute to quality improvement such as ease of assembly, maintenance, and small axis misalignment.

DESCRIPTION OF SYMBOLS 100: Light wave distance meter 101: Housing | casing 102: Base part 103: Lens barrel 110: Objective lens system 120: Ejection optical system 121: Collimator lens 122: Optical chopper 123: Density filter 124: Diaphragm 130: Light source 140: Ejection reflection optics System 141: Mirror member 142: Light transmitting / reflecting prism 142a: Reflecting surface 150: Light receiving / reflecting optical system 151: Dichroic mirror 152: Light receiving / reflecting prism 152a: Reflecting surface 160: Optical fiber 170: Collimating optical system 181: Cover glass

Claims (7)

An objective lens system having a first optical axis directed to the object to be measured and receiving light from the object to be measured;
An emission optical system having a second optical axis parallel to the first optical axis and emitting light from a light source that generates light in a predetermined wavelength region as measurement light that is parallel light;
An exit reflection optical system that reflects measurement light from the exit optical system and emits the measurement light toward the object to be measured along the first optical axis;
A light-receiving / reflecting optical system that reflects the measurement light reflected by the object to be measured and received by the objective lens system toward light-receiving means disposed at a position away from the first optical axis;
In a lightwave distance meter comprising:
The exit reflection optical system is arranged on the incident side of the objective lens system, the first reflecting means for guiding the measurement light to the incident side position of the objective lens system on the first optical axis, and the measurement light is A second reflecting means for reflecting the object to be measured along one optical axis;
The light receiving / reflecting optical system is disposed on the exit side of the objective lens system, and reflects reflected light of the measurement light from the object to be measured collected by the objective lens system from the first optical axis to the light receiving means. A light wave distance meter comprising light receiving and reflecting means for reflecting.   The light wave distance meter according to claim 1, wherein the exit reflection optical system and the light receiving reflection optical system can be individually adjusted. A parallel plate transparent body is disposed on the incident side of the objective lens system,
3. The light wave distance meter according to claim 1, wherein the second reflecting means is bonded to a surface adjacent to the objective lens system among both surfaces of the transparent body.   4. The light wave distance meter according to claim 1, wherein the light receiving unit is an optical cable having a light receiving surface disposed toward the first optical axis. 5.   The light wave distance meter according to any one of claims 1 to 4, wherein the light receiving / reflecting optical system includes a dichroic mirror that reflects only the predetermined wavelength region to the light receiving / reflecting means.   The optical wave distance meter according to any one of claims 1 to 5, further comprising a collimating optical system that magnifies and displays an image from the objective lens system.   The light wave distance meter according to any one of claims 1 to 6, further comprising modulation means for modulating the measurement light.