JPH03160317A - Laser light controlling device of measuring apparatus - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy by receiving a part of the reflecting light from a target, and controlling the amount of the projecting light so that the diameter of a monitoring spot is changed corresponding to the amount of the received light. CONSTITUTION:A part of the reflecting light from a target T is received by a photodetecting sensor 21 on an optical path of an inspecting optical system 20. The detecting signal is compared with a reference value within a memory of a control apparatus 22. A light attenuator 11 on an optical path of an illuminating optical system 10 is rotated in accordance with the result of the comparison. A filter is inserted so as to change the size of a laser beam spot thereby controlling the amount of the projecting light. If the illuminance in the periphery is constant, the size of the spot of the laser beam to be inspected is determined by the amount of the reflecting laser beam. Therefore, the measuring accuracy can be improved by reducing the size of the spot from S1 to S2 through reduction of the projecting laser beams.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser beam control device for a surveying instrument, and more particularly to a control device that appropriately controls the spot size of a laser beam.

(Prior Art) Conventional surveying instruments using laser light generally emit laser light (7) and guide the emitted laser light to a target T, which is an object to be measured, as shown in Fig. 6. An irradiation optical system 10 consisting of a laser beam oscillation medium 1, a mirror 2, an objective lens 3, etc. for irradiation, and an objective lens 3 and a focusing lens 4 for guiding the laser beam reflected from the target T to the viewer side. and an observation optical system 20 consisting of an eyepiece lens 5, etc. With this structure, an observer can perform a predetermined surveying operation while observing the reflected laser light spot and the focusing mirror 6 at the same time. It has become.

In such a surveying instrument, surveying accuracy generally improves as the spot size of the observed laser beam becomes smaller. For example, when using this surveying instrument as a pointer, the optical axis of the laser beam and the optical axis of the observation optical system 20 have a direct effect on measurement accuracy, so it is necessary to align both optical axes accurately. be. In the case of observation with the human eye, it is generally possible to judge a deviation of about 1/8 to 1/1O of the spot size, so as shown in Fig. 7, the smaller the spot size S of the observed laser light, the better. , it is possible to make more accurate adjustment by reducing the amount of deviation d between both optical axes. This also applies when aiming at an existing target, when measuring the amount of deviation from an existing target, or when installing a new target.

The spot size of the laser beam generally depends on the area of the radiation surface emitted from the laser beam oscillation medium 1, the spread angle of the laser beam at that time, the projection magnification of the irradiation optical system 10, the amount of reflected laser beam, the surrounding illuminance, etc. It is determined. Among these conditions, conventionally, in order to reduce the spot size of the laser beam and improve surveying accuracy, the spread angle of the laser beam is particularly selected to a small value, and the projection magnification of the irradiation optical system IO is increased. is used.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional technology, when the spread angle of the laser beam is reduced, the total length of the laser beam oscillation medium l needs to be increased, which leads to an increase in the size of the surveying instrument. Put it away. Moreover, when the projection magnification of the irradiation optical system 10 is increased,
As the beam diameter of the laser beam becomes larger, this goes against the demand for smaller surveying instruments, and also causes problems such as the irradiation position of the laser beam being shifted significantly due to a slight shift in the position of each element that makes up the optical system. be.

Further, as described above, the observed spot size of the laser beam is influenced by the amount of reflected laser beam and the surrounding illuminance, and the larger the former is, and the smaller the latter is, the larger the spot size is. On the other hand, in actual surveying work, the amount of reflected laser light varies depending on the distance from the surveying instrument to the target and changes in the reflectance of the target, and the surrounding illuminance changes from bright areas during the day to at night. There are many variations as it takes place in a dark place inside a tunnel. Therefore, the spot size of the observed laser beam changes depending on the surveying conditions, but conventional techniques cannot cope with this change and, as a result, cannot prevent a decrease in surveying accuracy. become.

The present invention was made to solve these problems, and it is an object of the present invention to reduce the spot size of the observed laser beam without increasing the size of the surveying instrument, thereby improving surveying accuracy. The purpose of the present invention is to provide a laser light control device for a surveying instrument that can perform the following functions.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a laser beam irradiation means for irradiating a target with a laser beam, an observation means for observing the laser beam reflected from the target, and a laser beam irradiation means for observing the laser beam reflected from the target. The apparatus includes a light amount control means for controlling the amount of laser light irradiated onto the target in order to change the spot size of the observed laser light.

(Function) The light amount control means controls the amount of laser light irradiated onto the target and changes the spot size of the laser light observed by the observation means.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a laser light control device for a surveying instrument to which the present invention is applied. In the figure, the same components as in FIG. 6, which shows a conventional device, are designated by the same reference numerals.

As shown in the figure, the irradiation optical system 10 includes a laser beam oscillation medium l that emits a laser beam, for example, a He-Ne gas laser, and a condenser for condensing and focusing the emitted laser beam. An optical lens 15, a focusing lens 16, and first and second mirrors 2 that guide the laser beam from the focusing lens 16.
a, 2b, and an objective lens 3 for condensing the laser light from these mirrors and irradiating it onto a target T, which is an object to be measured.

On the other hand, the observation optical system 20 includes the objective lens 3 for condensing the laser beam reflected from the target T, a focusing lens 4 for focusing the laser beam from the objective lens 3, and the focusing lens 4 for focusing the laser beam from the objective lens 3. It is composed of a focusing mirror 6 onto which a laser beam is projected, and an eyepiece lens 5.

A light receiving sensor 2l is arranged on the optical path of the observation optical system 20. This light receiving sensor 2l is connected to a control device 22 which will be described later.
It is electrically connected to the control device 22, detects the amount of laser light, and supplies the signal to the control device 22. Further, a light attenuator 11 is provided on the optical path of the irradiation optical system IO. As shown in FIG. 2, the dimmer I1 consists of a disc-shaped filter whose density changes in multiple steps (eight steps in this example) in the circumferential direction, and is connected to the shaft of the stepping motor 12. . This stepping motor 12 is electrically connected to the control device 22. Therefore, stepping motor 1
By controlling the rotation angle of 2 by the control device 22, the concentration of the light attenuator l1, that is, the amount of emitted laser light is controlled.

FIG. 3 shows the circuit configuration of the control device 22. The control device 22 includes a current-to-voltage converter 221 that converts a current signal from the light receiving sensor 21 into a voltage signal, and a current-to-voltage converter 221. a low-pass filter 222 that cuts noise in the voltage signal from the low-pass filter 222; an amplifier 223 that amplifies the output signal from the low-pass filter 222;
A/A that converts the voltage analog signal from the
The D converter 224, the reference value memory 225 that stores the reference value of the amount of emitted laser light, and the rotation of the stepping motor 12 based on the signal from the A/D converter 224 and the reference value stored in the reference value memory 225. It is comprised of a microcomputer 226 that calculates the moving angle, a drive circuit 227 that drives the stepping motor l2 in accordance with a control signal from the microcomputer 226, and the like.

With the above configuration, the amount of laser light reflected from the target A and entering the observation optical system is constantly detected by the light receiving sensor 2l, and the detected amount of light and the reference value memory 22 are stored.
5 and the reference value stored in microcomputer 226.
The amount of laser light reflected from the target T and incident on the observation optical system is controlled by driving the stepping motor l2 and rotating the attenuator l1 according to the results. The amount of emitted laser light can be controlled so that the value is always the optimum value.

As described above, the spot size of the observed laser light is determined by the amount of reflected laser light if the surrounding illuminance is constant. FIG. 4 shows an example of this, and the dotted line and solid line in the figure represent the radiation amount of the laser beam when the light is not attenuated and when the light is attenuated by the dimmer 1l, respectively. It can be seen from the figure that by attenuating the emitted laser light, the amount of reflected laser light decreases, and the spot size decreases, for example, from S1 to S. Therefore, by controlling as described above, it is possible to control the observed laser beam spot to a small optimal size regardless of changes in the distance from the surveying instrument to the target or the reflectance of the target, thereby increasing survey accuracy. Can be done.

FIG. 5 is an overall configuration diagram of a laser light control device for a surveying instrument to which a second embodiment of the present invention is applied. This embodiment differs from the previously described embodiments only in that the light receiving sensor 2l, the control device 22, and the stepping motor 12 are omitted, and the dimmer 11 is manually operated. Therefore,
In this embodiment, the spot size of the laser beam can be adjusted to the minimum size by operating the light attenuator 11 according to the observer's judgment while observing the spot of the laser beam.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented in various embodiments. For example, in the i-th embodiment, the light receiving sensor is not directly provided on the optical path of the observation optical system, but a beam splitter, a half mirror, etc. provided on the optical path is used to direct a portion of the reflected laser light to the optical path of the observation optical system. The light may be guided to a light receiving sensor placed outside, or the light receiving sensor may be placed near the optical path of the observation optical system at a position where it can receive the reflected laser light, or it may be placed on the target side instead of on the survey instrument side.

Further, in the above-described embodiment, a filter whose concentration changes in multiple steps in the circumferential direction is used as a means for attenuating the emitted laser beam, but the present invention is not limited to this, and a filter whose density changes continuously, or other means, such as variable apertures or polarizers,
Alternatively, a liquid crystal whose concentration changes electrically may be used, and furthermore, the driving method, installation position, etc. can be changed in various ways.

Furthermore, in this embodiment, since a He-Ne gas laser whose radiation amount cannot be controlled originally is used as the laser beam oscillation medium, the laser beam after being emitted from the medium is attenuated. When using a laser beam oscillation medium with a controllable amount of radiation, such as a semiconductor laser diode, it is also possible to directly control the amount of laser light emitted from the medium according to the detection output of the light receiving sensor. be.

(Effects of the Invention) As described in detail above, according to the laser light control device for a surveying instrument of the present invention, the spot size of the observed laser light can be reduced without increasing the size of the surveying instrument, and therefore the surveying accuracy This has effects such as being able to improve performance.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing a laser light control device for a surveying instrument according to a first embodiment of the present invention, Fig. 2 is a diagram showing a filter that attenuates the emitted laser light, and Fig. 3 is a diagram showing the control of the filter. FIG. 4 is a diagram explaining the operation of the device shown in FIG. 1, FIG. 5 is a block diagram similar to FIG. FIG. 7 is a block diagram similar to FIG. 1 showing a conventional laser beam control device for a surveying instrument, and a diagram illustrating the relationship between the spot size of the laser beam and surveying accuracy. DESCRIPTION OF SYMBOLS 1... Laser beam oscillation medium, 6... Focusing mirror, 1l... Attenuator, 12... Stepping mode, 2l... Light receiving sensor, 22... Control device, T... target.

Claims (3)

[Claims] (1) Laser light irradiation means for irradiating a target with laser light, observation means for observing the laser light reflected from the target, and irradiation on the target in order to change the spot size of the laser light observed by the observation means. 1. A laser light control device for a surveying instrument, comprising a light amount control means for controlling the amount of laser light. (2) The laser light control device for a surveying instrument according to claim 1, wherein the light amount control means controls the amount of laser light irradiated onto the target continuously or in multiple stages. (3) Further comprising a detection means for detecting the amount of laser light reflected from the target, and the light amount control means controls the amount of laser light irradiated to the target according to the amount of laser light detected by the detection means. Claim 1 to control
A laser light control device for a surveying instrument according to item 1 or 2.