JP2004191063A - Light wave distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light wave distance measuring device capable of removing a trouble hindering ranging in a short distance, even when a reflecting mirror provided in an emission optical system, for reflecting measuring light from a light source part toward an objective lens, is provided coaxially with the center of the objective lens. <P>SOLUTION: This light wave distance measuring device is provided with the emission optical system 1 for irradiating the measuring light toward a measuring object, and a light-receiving optical system 2 having a light-receiving element 11 for receiving reflected measuring light. The emission optical system 1 is provided with the light source part for emitting linearly-polarized measuring light, the reflecting mirror 8 for reflecting the measuring light from the light source part toward the objective lens 9, and a quarter-wave plate 10 for converting the linearly-polarized measuring light reflected by the reflecting mirror 8 into circularly polarized light and converting circularly-polarized reflected measuring light into linear polarized light. The reflecting mirror 8 provided coaxially with the center of the objective lens 9 reflects the measuring light from the light source part and guides it to the quarter-wave plate 10, and transmits the reflected measuring light entering after passing the quarter-wave plate 10 and guides it to the light-receiving element 11. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a lightwave distance measuring device.
[0002]
[Prior art]
Conventionally, an emission optical system that emits measurement light through an objective lens and a light receiving optical system that receives reflected measurement light incident through the objective lens are coaxially arranged, and measurement from a light emitting element of a light source unit is performed. 2. Description of the Related Art There is known an optical distance measuring apparatus in which a reflecting mirror for reflecting light toward an objective lens is provided eccentrically with respect to the center of the objective lens (for example, see Patent Document 1).
[0003]
In general, when the retroreflective prism is at a long distance, that is, when the measurement point is at a long distance, the measuring light emitted from the objective lens and the reflected measuring light entering the objective lens from the retroreflective prism are diffused at all. Therefore, even if a reflection mirror that reflects the measurement light of the light emitting element toward the objective lens is provided concentrically with the center of the objective lens, the reflection measurement light is received by the light receiving element of the light receiving optical system.
[0004]
On the other hand, when the retroreflective prism is in the vicinity, that is, when the measuring point is at a short distance, the spread of the measurement light emitted from the objective lens toward the retroreflective prism and the reflected measurement light incident on the objective lens Therefore, there is a problem that the reflection mirror interferes with the reflection measurement light incident on the light receiving optical system and is not received by the light receiving element.
[0005]
Even when the retroreflection prism is in the vicinity, the reflection mirror is provided eccentrically with respect to the center of the objective lens, so that the reflection measurement light incident on the objective lens can be received without being disturbed by the reflection mirror. Distance measurement can be performed without any trouble.
[Patent Document 1]
JP-A-4-319687 (FIGS. 1 and 2)
[0006]
[Problems to be solved by the invention]
However, if the amount of eccentricity between the center of the mirror and the center of the objective lens is too small, the ratio of the reflection measurement light incident on the objective lens during short distance measurement being disturbed by the reflection mirror is large, and light reception is difficult. It may be.
[0007]
Further, if the center of the reflecting mirror and the center of the objective lens are too eccentric, when the retroreflective sheet is used, the reflection measurement light incident on the objective lens is imaged at a position off the light receiving element. Therefore, there is an inconvenience that short distance measurement is hindered, and an optical member for correction is required. The technique disclosed in Patent Document 1 is not preferable because the amount of reflected measurement light incident on the light receiving element changes depending on the amount of eccentricity between the center of the reflecting mirror and the center of the objective lens.
[0008]
The present invention has been made in view of the above circumstances, and a case where a reflecting mirror provided in an emission optical system and reflecting measurement light from a light source unit toward an objective lens is provided coaxially with the center of the objective lens. However, it is an object of the present invention to provide a lightwave distance measuring device that can solve the problem of hindering short distance measurement.
[0009]
[Means for Solving the Problems]
The lightwave distance measuring device according to claim 1, wherein an emission optical system that irradiates the measuring object with the measuring light and a light receiving optical system that has a light receiving element for receiving the reflected measuring light are provided. In the distance measuring device,
The emission optical system includes a light source unit that emits linearly polarized measurement light, a reflection mirror that reflects the measurement light from the light source unit toward the objective lens, and a linearly polarized measurement light that is reflected by the reflection mirror. A quarter-wave plate for converting the light into circularly polarized light and converting the reflected measurement light of circularly polarized light into linearly polarized light is provided. The reflection mirror is provided concentrically with the center of the objective lens, and measures the light from the light source unit. Light is reflected and guided to the １ ／ wavelength plate, and guided to the light receiving element through the reflected measurement light that passes through the 波長 wavelength plate and enters.
[0010]
The light wave distance measuring device according to claim 2, wherein the light source unit has a light source that emits laser light, and a polarizing plate that passes the laser light from the light source, and the polarizing plate converts the laser light into linearly polarized light. It is characterized by doing.
[0011]
According to a third aspect of the present invention, in the optical distance measuring apparatus, the quarter wavelength plate is provided on the objective lens.
[0012]
The lightwave distance measuring device according to claim 4, wherein a split mirror that splits light from the light emitting element into reference light and measurement light, and a measurement optical path on which the light from the light emitting element is provided with the polarizing plate. An optical path switching device for switching an optical path between a reference optical path leading to the light receiving element and a light amount adjuster for adjusting the light amount of the measurement light is provided.
[0013]
According to a fifth aspect of the present invention, there is provided an optical distance measuring apparatus including a collimating optical system for collimating an object to be measured.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 1 is an optical diagram of a first embodiment of an optical distance measuring apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes an exit optical system, 2 denotes a light receiving optical system, and 3 denotes a retroreflective prism.
[0015]
The emission optical system 1 includes a light emitting element 4, a collimator lens 5, a polarizing plate 6, a total reflection mirror 7, a reflection mirror 8, and an objective lens 9. The light emitting element 4, the collimating lens 5, and the polarizing plate 6 constitute a light source unit.
[0016]
The light emitting element 4 is composed of, for example, a laser diode, the collimating lens 5 converts light emitted from the laser diode into a parallel light beam as measurement light, and the polarizing plate 6 converts the parallel light beam into a linearly polarized light having a predetermined polarization direction, for example. It serves to generate S-polarized linearly polarized light.
[0017]
The S-polarized linearly polarized measurement light is reflected by the total reflection mirror 7 and guided to the reflection mirror 8. The center of the reflecting mirror 8 is disposed coaxially with the center O of the objective lens 9. The reflection mirror 8 has a role of reflecting S-polarized light and transmitting P-polarized light, and reflects the measurement light reflected by the total reflection mirror 7 toward the objective lens 9.
[0018]
A 波長 wavelength plate 10 is provided between the objective lens 9 and the mirror 8. Here, the 波長 wavelength plate 10 is formed as a film on the inner surface of the objective lens 9. Note that the quarter-wave plate 10 may be an optical member attached to the inner surface of the objective lens 9 instead of a film.
[0019]
The quarter-wave plate 10 has a role of converting linearly polarized light emitted from the objective lens 9 into circularly polarized light and converting circularly polarized light incident on the objective lens 9 into linearly polarized light. . The circularly polarized measurement light P1 passing through the quarter-wave plate 10 and passing through the central portion 9A of the objective lens 9 is guided to the retroreflection prism 3, is reflected by the retroreflection prism 3, and the objective lens 9 is present again. In the direction you want.
[0020]
The reflection measurement light P2 reflected by the retroreflection prism 3 is guided to the light receiving optical system 2 through the central portion 9A and the peripheral portion 9B of the objective lens 9. The light receiving optical system 2 is provided with a light receiving element 11. The light receiving element 11 is connected to a measuring circuit (not shown).
[0021]
The circularly-polarized reflection measurement light P2 passing through the central portion 9A of the objective lens 9 passes through the quarter-wave plate 10 again, and is guided to the reflection mirror 8 as P-polarization reflection measurement light orthogonal to S-polarization. Since the reflection mirror 8 has a characteristic of reflecting S-polarized light and transmitting P-polarized light, the reflection measurement light P2 passing through the central portion 9A of the objective lens 9 can be reflected by the reflection mirror 8 without being disturbed by the reflection mirror 8. And is received by the light receiving element 11.
[0022]
The reference light is guided to the light receiving element 11 via a known reference light path, and the distance to the retroreflective prism 3 is measured by measuring the phase difference between the reference light and the reflection measurement light. .
(Embodiment 2)
FIG. 2 is an optical diagram of Embodiment 2 of the lightwave distance measuring apparatus according to the present invention. In Embodiment 2 of the present invention, the exit optical system 1 includes a collimator lens 5 and a polarizing plate 6. Is provided with a split mirror 12 for splitting light from the light emitting element 4 into measurement light and reference light, and a total reflection mirror 13 for guiding the light from the light emitting element 4 to the measurement optical path where the polarizing plate 6 is present and the light receiving element 11. There is provided an optical path switch 14 for switching between a reference optical path and a reference optical path. Between the polarizing plate 6 and the total reflection mirror 7, a light amount adjuster 15 for adjusting the light amount of the measurement light is provided.
[0023]
The light receiving optical system 2 is provided with a wavelength division mirror 17 which constitutes a part of the collimating optical system 16, and the reflection measurement light incident through the objective lens 9 is reflected by the wavelength division mirror 17 in the direction in which the light receiving element 11 exists. The visible light passes through the wavelength division mirror 17 and is guided to the eyepiece 18. The surveying operator can collimate the retroreflective prism 3 through the eyepiece 18.
[0024]
When the light emitting element 4 is a semiconductor laser element and emits linearly polarized light, the polarizing plate 6 need not be provided.
[0025]
【The invention's effect】
Since the invention according to claims 1 to 5 is configured as described above, the reflection mirror provided in the emission optical system and reflecting the measurement light from the light source unit toward the objective lens is provided at the center of the objective lens. Even in the case of being provided coaxially with the camera, it is possible to eliminate the inconvenience that hinders short distance measurement.
[Brief description of the drawings]
FIG. 1 is an optical diagram of a first embodiment of an optical distance measuring apparatus according to the present invention.
FIG. 2 is an optical diagram of a lightwave distance measuring apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Outgoing optical system 2 ... Light receiving optical system 6 ... Polarizing plate 8 ... Reflecting mirror 9 ... Objective lens 10 ... 1/4 wavelength plate 11 ... Light receiving element

Claims (5)

An emission optical system that irradiates the measurement light toward the object to be measured, and a light-wave distance measuring device provided with a light-receiving optical system having a light-receiving element for receiving the reflected measurement light,
The emission optical system includes a light source unit that emits linearly polarized measurement light, a reflection mirror that reflects the measurement light from the light source unit toward the objective lens, and a linearly polarized measurement light that is reflected by the reflection mirror. A quarter-wave plate for converting the light into circularly polarized light and converting the circularly polarized reflection measurement light into linearly polarized light; the reflecting mirror is provided concentrically with the center of the objective lens; A light wave distance measuring device, wherein light is reflected to guide the light to the quarter-wave plate, and is guided to the light receiving element through the reflected measurement light that passes through the quarter-wave plate and enters. The light source unit according to claim 1, wherein the light source unit includes a light source that emits a laser beam, and a polarizing plate that passes the laser beam from the light source, wherein the polarizing plate converts the laser beam into linearly polarized light. Lightwave distance measuring device. The light wave distance measuring device according to claim 1, wherein the quarter wavelength plate is provided on the objective lens. The emission optical system includes a split mirror that splits light from the light emitting element into reference light and measurement light, and guides light from the light emitting element to a measurement optical path on which the polarizing plate is provided and the light receiving element. The lightwave distance measuring device according to claim 2, further comprising: an optical path switch that switches an optical path between the optical path and an optical path, and a light amount adjuster that adjusts a light amount of the measurement light. The optical distance measuring apparatus according to claim 3, further comprising a collimating optical system that collimates the measurement target.

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