JP2000147121A - Light-wave distance meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a tangent error, and to make securable a large quantity of light reception by arranging a rhomboid prism for changing a light path near the optical axis of a light-reception objective lens in the optical axis of measurement light in front of the light reception objective lens. SOLUTION: The rhomboid prism 7 used as a light path change means is arranged in front of a lens 41 so that an optical axis 2a of measurement light where light is transmitted from a light transmission objective lens 21 coincides with an optical axis 4a of a light reception objective lens. As a result, the measurement light from a laser diode 2 is reflected on reflection surfaces 71 and 72 of the prism 7 to advance toward a target 3, and the measurement light being reflected by a measurement object 3 passes on the same optical axis, is received by a lens 41, and is condensed at a tip 42 of an optical fiber 4 along the optical axis 4a, thus always condensing at the tip 42 of the optical fiber 4 even when the distance between a light wave range finger 1 and the target 3 is changed. Also, since the prism 7 is sufficiently small for the effective area of the lens 4, the amount of condensation at the tip 42 of the optical fiber is increased, and the influence of disturbance is hard to be received, thus preventing range-finding accuracy from being decreased even when measurement distance becomes short.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light wave objective having a light transmitting objective lens for transmitting measurement light from a light source to a target and a light receiving objective lens for receiving the measurement light reflected by the target. Regarding a distance meter.

[0002]

2. Description of the Related Art As a conventional lightwave distance meter, a light transmitting objective lens for transmitting a measuring light from a light source to a target and a measuring light reflected by the target are disclosed in, for example, Japanese Patent Publication No. 8-510324. There is known an optical distance meter in which a light receiving objective lens for receiving light and condensing the light on a light receiving sensor is juxtaposed. In this device, since the optical axis of the transmitting objective lens and the optical axis of the receiving objective lens are separated from each other, the optical path for transmitting the measuring light from the transmitting objective lens to the target and the measuring light reflected by the target are This is different from the optical path returning to the light receiving objective lens. That is, the measurement light is transmitted from the light transmission objective lens along the optical axis of the light transmission objective lens, but the measurement light reflected by the target and received by the light reception objective lens is relative to the optical axis of the light reception objective lens. The light is received by the light receiving objective lens from the inclined direction. The inclination of the light receiving objective lens with respect to the optical axis increases as the distance between the optical distance meter and the target decreases. When the inclination of the light receiving direction of the measurement light with respect to the optical axis of the light receiving objective lens increases, the image forming position after passing through the light receiving objective lens deviates from the optical axis of the light receiving objective lens,
Light is not received by the light-receiving sensor arranged on the optical axis of the light-receiving objective lens. For this reason, the conventional lightwave distance meter is configured so that the position of the light receiving sensor can be manually moved, and when the distance to the target becomes short, the position of the light receiving sensor is moved to form an image on the light receiving sensor. I have.
Alternatively, in the other lightwave distance meter described in the above publication, a mirror or a prism is arranged between the light receiving objective lens and the light receiving sensor, and when the measuring light is received obliquely, the optical path of the measuring light is bent. The light receiving sensor is configured to receive light.

[0003]

In the above-mentioned conventional lightwave distance meter, the measuring light reflected by the target is received with an inclination with respect to the optical axis of the light receiving objective lens. A so-called tangent error, which is slightly longer than twice the distance between the meter and the target, occurs. If the distance measurement error due to the tangent error is constant, it can be easily corrected. However, since the tangent error changes when the distance between the lightwave distance meter and the target changes, it is difficult to correct it. . In the case where a mirror or a prism is arranged between the light receiving objective lens and the light receiving sensor, only a part of the measurement light received by the light receiving objective lens can be guided to the light receiving sensor, and the amount of light received by the light receiving sensor is reduced. As a result, there is a problem that the distance measurement accuracy is adversely affected because the influence of disturbance is reduced.

[0004] In view of the above problems, an object of the present invention is to provide a lightwave distance meter that can ignore the effect of a tangent error and can secure a large amount of light received by a light receiving sensor.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a light transmitting objective lens for transmitting measurement light from a light source to a target, and receiving and receiving measurement light reflected by the target. In a lightwave distance meter in which a light receiving objective lens condensed on a sensor is arranged in parallel, a light path changing means for changing the optical path of the measurement light transmitted from the light transmitting objective lens to a position near the optical axis of the light receiving objective lens is received. It is characterized by being provided in front of the objective lens.

[0006] Further, a light wave in which a light transmitting objective lens for transmitting measurement light from a light source to a target and a light receiving objective lens for receiving the measurement light reflected by the target and condensing the light on a light receiving sensor are arranged in parallel. In the rangefinder, an optical path changing means for changing the optical path of the measurement light transmitted from the light transmitting objective lens so as to match the optical axis of the light receiving objective lens is provided in front of the light receiving objective lens. Features.

If the optical path of the measurement light transmitted from the light transmitting objective lens is changed toward the optical axis of the light receiving objective lens, the light received by the light receiving objective lens is received even when the optical distance meter approaches the target. The inclination angle of the measurement light becomes small, and the light condensing position does not deviate from the optical axis of the light receiving objective lens. Further, even if the distance between the lightwave distance meter and the target changes, the change in the light receiving angle to the light receiving objective lens is small, so that the tangent error can be ignored. On the other hand, since the light path changing means is provided in front of the light receiving objective lens, the light path changing means can be easily added to the conventional light wave distance meter to obtain the light wave distance meter according to the present invention.

By the way, if the optical path of the measurement light transmitted from the light transmitting objective lens is changed toward the optical axis of the light receiving objective lens until it coincides with the optical axis of the light receiving objective lens, the conventional problem can be further solved. can do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a lightwave distance meter according to the present invention, which emits a measurement light whose luminance is modulated at a predetermined frequency from a visible light laser diode 2 as a light source. The light is converted into parallel rays by the light transmitting objective lens 21 and transmitted forward from the light transmitting window 22. On the other hand, a target 3 is disposed in front of the optical distance meter 1, and the measurement light from the visible laser diode 2 is reflected by the target 3. The measurement light transmitted from the light transmission window is reflected by the target 3 and returns to the lightwave distance meter 1. The reflected measurement light is received by the light receiving objective lens 41, and the distal end 4 of the optical fiber 4 disposed on the optical axis 4a of the light receiving objective lens 41.
It is condensed on 2. It is desirable to use an optical fiber 4 having a large aperture angle. The measuring light condensed at the tip 42 passes through the optical fiber 4 and is guided to a light receiving element (not shown). An oscillating plate 6 on which a mirror 61 is mounted is disposed in front of the light transmitting objective lens 21, and the optical path of the measurement light transmitted from the light transmitting objective lens 21 is blocked by the mirror 61, and an optical fiber The measurement light is reflected toward the tip 42 of the fourth light source 4. By swinging the swinging plate 6 in this manner, the measurement light reflected by the mirror 61 and the measurement light reflected by the target 3 are selectively incident on the tip end 42 of the optical fiber 4. . Then, the distance between the lightwave distance meter 1 and the target 3 is determined from the phase shift of the signal of the predetermined frequency that modulates both measurement lights. Reference numeral 5 denotes an aperture, which limits the amount of measurement light by a mirror 61 to reduce phase distortion. Reference numeral 23 denotes a dustproof glass, which is attached at an appropriate angle to prevent the transmitted measurement light from being reflected by the dustproof glass 23 and returning to the same optical path.
The optical axis 4a of the light receiving objective lens 41 and the light transmitting objective lens 2
The first optical axis 2a is set to intersect approximately 30 m ahead.

By the way, referring to FIG. 2 in addition to FIG.
In the present invention, the rhombic prism 7 is an optical path changing means for changing the optical path of the measuring light transmitted from the light transmitting objective lens 21 so that the optical axis 2a of the measuring light coincides with the optical axis 4a of the light receiving objective lens 41.
Was arranged. The rhombic prism 7 has reflecting surfaces 71 and 72 formed at both ends of a rectangular prism so as to be parallel to each other and inclined at an angle of 45 degrees. As described above, by aligning the optical axis 2a of the light transmitting objective lens 21 with the optical axis 4a of the light receiving objective lens 41, the measurement light reflected by the reflection surface 72 toward the target 3 and the measurement light reflected by the target 3 and returned. The incoming measurement light reciprocates on the same optical axis. The measurement light received by the light receiving objective lens 41 is
Since the light is received along the first optical axis 4 a, the light is always focused on the tip 42 of the optical fiber 4 even if the distance between the lightwave distance meter 1 and the target 3 changes. As shown in FIG. 2, the portion of the rhombic prism 7 between the reflecting surface 72 and the reflecting surface 71 does not transmit the measurement light reflected by the target 3 and returned as it is. Since it is sufficiently small with respect to the effective area of the lens 41, the tip 42 of the optical fiber 4
Since the amount of measurement light condensed on the surface increases, and the influence of disturbance is less likely to occur, even if the measurement distance is shortened, the distance measurement accuracy does not decrease.

In the above embodiment, the optical path of the optical axis 2a of the light transmitting objective lens 21 is changed until it coincides with the optical axis 4a of the light receiving objective lens 41. However, it is not always necessary to change the optical path until the optical axis 2a coincides. The distance between the optical axis 2a and the optical axis 4a may be reduced to such an extent that can be ignored. In this case, the rhombic prism 7 can be shortened, and the central portion of the light receiving objective lens 41 having the largest amount of received light does not need to be covered with the reflection surface 72 of the rhombic objective lens 7. Can be further increased. In the above embodiment, the rhombic prism 7 is used as the optical path changing means, but an optical fiber or another type may be used. In addition, the same measurement can be performed even when a reflecting mirror is provided on the target.

[0012]

As is apparent from the above description, the present invention can be applied to an optical distance meter in which a light transmitting objective lens and a light receiving objective lens are arranged side by side. The tangent error does not occur because the optical axes are close to each other or coincide with each other, and the light-receiving element or light-receiving part must be moved because the focusing position does not change even if the distance between the lightwave distance meter and the target changes. It is not necessary to change the optical path of the measurement light after passing through the light receiving objective lens.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a partial front view showing a positional relationship between a rhombic prism and an objective lens.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lightwave distance meter 2 laser diode 3 target 4 optical fiber 21 transmitting objective lens 41 receiving objective lens

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Futa Nagata 260-63 Yanagimachi, Hase-ji, Atsugi-shi, Kanagawa Prefecture Inside the Sokia Atsugi Plant (72) Inventor Masamitsu Endo 260-63 Yanagimachi, Hase-shi, Atsugi-shi, Kanagawa Sokia Corporation Atsugi Plant F term (reference) 2F065 AA06 DD12 FF13 FF61 GG06 GG12 HH03 JJ01 JJ15 LL01 LL02 LL04 LL12 LL13 LL30 LL46 2F112 AD10 BA07 CA12 DA10 DA25 DA32 DA40 5J084 AA05 AD02 BA04 BB02 BB11 BB11

Claims (2)

[Claims] 1. A light wave having a light transmitting objective lens for transmitting measurement light from a light source to a target and a light receiving objective lens for receiving the measurement light reflected by the target and condensing the measurement light on a light receiving sensor. In the distance meter, an optical path changing means for changing the optical path of the measurement light transmitted from the light transmitting objective lens to a position near the optical axis of the light receiving objective lens is provided in front of the light receiving objective lens. Lightwave rangefinder. 2. A light wave having a light transmitting objective lens for transmitting measurement light from a light source to a target, and a light receiving objective lens for receiving the measurement light reflected by the target and condensing the measurement light on a light receiving sensor. In the rangefinder, an optical path changing means for changing the optical path of the measurement light transmitted from the light transmitting objective lens so as to match the optical axis of the light receiving objective lens is provided in front of the light receiving objective lens. Characteristic lightwave distance meter.