JPH06347270A - Automatic collimation device of surveying instrument - Google Patents

Abstract

PURPOSE:To obtain the title collimation device wherein a long distance can be searched easily and a search range can be changed by a simple structure irrespective of whether a distance is near or far. CONSTITUTION:The title collimation device is provided with a pulsed laser diode 1 which radiates a pulsed beam to an object 9 to be measured, with a plurality of photoelectric conversion cells 6a which convert a reflected pulsed beam from the object 9 to be measured into an electric signal and with an objective lens 8 which converges the pulsed beam from the pulsed laser diode 1. The light-receiving face of each photoelectric conversion cell 6a is arranged two-dimensionally, the angle of divergence of the pulsed beam from the objective lens 8 is controlled, according to a distance up to the object 9 to be measured, by a lens 2 and a motor 3 which drives the lens 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic collimation device for a surveying instrument, that is, a device for aligning a reflecting member installed at a measuring point with an optical axis of a telescope of the surveying instrument.

[0002]

2. Description of the Related Art A conventional device of this type is a mechanically driven device for searching for an object to be measured by mechanically driving a collimation device having a constant light emission direction, and a laser diode. Laser light is emitted two-dimensionally using a deflecting element such as an acousto-optical element, and the light reflected from the target within the scanning range by the light is detected by a light receiving device, and the survey light is used by the detected light. There is known an optical scanning type device which obtains a direction from a main body to a target and collimates it (Japanese Patent Laid-Open No. 4-166791).

[0003]

However, the mechanically driven apparatus has a problem that it takes a very long time to detect the reflecting member for mechanical scanning.

On the other hand, in the optical scanning type apparatus, although the detection of the reflecting member is fast, a power source and a circuit for driving the deflecting element are required, and the optical path of the optical system becomes complicated. There is a problem that it is difficult to miniaturize, and because the output of the laser diode cannot be increased so much because of the protection of the human body, it is difficult to search for a long distance. Furthermore, since this optical scanning device has a fixed search angle (beam deflection angle), it is difficult to change the search range, and there is a problem that the actual search area at a short distance is narrow.

As a conventional technique for changing the search range, there is provided an automatic focusing device for limiting a target when a plurality of targets exist within the search range, such as a TV camera. There is a technique in which data can be input in a wide range of field angles in advance by using an image pickup device and the effective field angle is limited by an electric circuit or a computer (Japanese Patent Laid-Open No. 4-43475). ). However, this device requires a circuit for controlling the CCD and a circuit for processing a signal obtained by the CCD, so that there is a problem that the circuit scale becomes very large.

The present invention has been made in view of the above circumstances, and its object is to facilitate a long-distance search and to have a simple structure capable of changing the search range regardless of the distance. Is to provide.

[0007]

In order to solve the above-mentioned problems, a surveying instrument according to a first aspect of the present invention has a pulse light generating means for emitting pulsed light to an object to be measured and a light receiving surface arranged two-dimensionally. Then, a light receiving means for converting the reflected pulsed light from the measurement object into an electric signal, a focusing optical system for focusing the pulsed light from the pulsed light generating means, and a spread angle of the pulsed light from the focusing optical system And a pulsed light divergence angle control means for controlling according to the distance to the measurement object.

[0008]

Since the pulsed light generating means is used as the light source, the output can be increased to facilitate long-distance search and protect the human body. Further, since the light receiving surfaces of the plurality of light receiving means are two-dimensionally arranged, the position of the measuring object can be detected.

Further, a converging optical system for converging the pulsed light from the pulsed light generating means and a pulsed light divergence angle for controlling the divergence angle of the pulsed light from the converging optics according to the distance to the object to be measured. With the control means, the search range can be freely changed according to the distance to the measurement object.

[0010]

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

FIG. 1 is an overall configuration diagram of a surveying instrument according to an embodiment of the present invention. As the light source, a pulse laser diode 1 capable of instantaneously obtaining a high output was used. The pulse lighting is several watts to several hundreds watts, and the pulse width is several nanoseconds to several hundred nanoseconds. Since the light output for protection of the human body can be expressed as the integrated value of the emitted light with respect to the time axis, a high output element can be used by adopting the pulse lighting method, and a large instantaneous peak light amount per single area can be obtained.

An objective lens 8 is arranged in front of the pulse laser diode 1, and the pulsed light emitted from the objective lens 8 is applied to an object 9 to be measured. A lens 2 (for example, a convex lens) that controls the divergence angle of the pulsed light emitted from the objective lens 8 is disposed between the pulse laser diode 1 and the objective lens 8. The lens 2 is driven in the optical axis direction by the motor 3. A half mirror-4 is arranged between the lens 2 and the objective lens 8 to reflect the reflected pulsed light reflected by the measuring object 9 to the light receiving device 6 side. A focusing lens 5 for focusing the light receiving device 6 and the measuring object 9 is arranged between the light receiving device 6 and the half mirror 4, and the lens 5 is driven by the motor 7. It The light source 1 to the motor 7 and the circuit of FIG. 4 described later are arranged in the telescope 10 shown by a dotted line.

When the emission angle of the pulsed light is expanded by the pulsed light divergence angle control means composed of the lens 2 and the motor 3, the amount of emitted light per single area is reduced,
A wide range of searches can be made at once. Further, when the emission angle of the pulsed light is narrowed, the search range is narrowed, but the amount of emitted light per single area is large.

The measuring object can be limited by narrowing the pulsed light divergence angle and limiting the search range.

The light receiving device 6 used is a two-dimensionally arranged photo diode array formed in a cell shape. However, a linear image sensor capable of high-speed response, a two-dimensional array of photodiodes, or a CCD may be used. It is possible to use CCD, but C
It is necessary to synchronize the charge / discharge timing of the CCD with the pulse light transmission timing in order to avoid the timing at which the light receiving pulse comes when the CD charge is discharged. Further, it is necessary to keep the capacitive load of the CCD small according to the pulse width used.

FIG. 2A shows an example in which nine photoelectric conversion cells 6a are two-dimensionally arranged in one package, and FIG.
(B) shows an example in which four photoelectric conversion cells 6a are used, and a circle in the figure is an image forming point of the measurement object 9 when the focus and collimation with the measurement object 9 are in an ideal state. Represents

When the focus is in agreement but the collimation, that is, the position of the image formation point is deviated, the CPU 16 responds to the light receiving device.
The measurement target 9 is controlled to be located on the optical axis of the main body 10. For example, when the light receiving device of FIG. 2 (a) is used, the surveying instrument main body 10 is controlled so that the reflected light intensity of the central photoelectric conversion cell 6a is maximized. Collimation can be performed by controlling the surveying instrument main body 10 so that the reflected light intensity of the photoelectric conversion cells 6a becomes uniform.

Control of the surveying instrument main body 10 is performed by controlling the surveying instrument main body 2
It is driven by two electric motors 18 and 19 in the horizontal and vertical directions.

Further, the control from the time when the focus is deviated will be described. It is assumed that the reflected pulsed light can be detected even if it is weak. Since the timing of sending the pulsed light is known, if the light can be received even if there is a slight defocus, the approximate distance information can be obtained. That is, the delay time measuring circuit 1
Distance information is obtained by measuring the time difference between transmission and reception of pulsed light at 7, and the CPU 16 controls the motor 7 so as to move the position of the lens 5 based on this distance information. The light receiving device 6 repeats the distance measurement and the lens driving until the peak value of the reflected pulsed light is detected, thereby performing more accurate focus matching.

FIG. 4 shows one photoelectric conversion cell 6 of the light receiving device 6.
It is a circuit diagram for processing the information from a in CPU16. It should be noted that the CPU 16 is one in common, but a similar circuit is connected to each cell. The reflected pulsed light incident on the photoelectric conversion cell 6a is photoelectrically converted, and a voltage corresponding to the converted current value is generated across the load resistor 11. The electric signal is sent to the peak detection circuit 15 via the high-pass filter 13 and the amplifier 14, converted into a digital signal by the peak detection circuit 15, and the peak light amount value is given to the CPU 16. On the other hand, the delay time measuring circuit 17 measures the time difference from the transmission signal indicating the time information of the timing at which the pulse lighting is performed, digitizes the result, and the CPU 16
Send to. The delay time measuring circuit 17 is not necessary for all the photoelectric conversion cells 6a, but is necessary for a system that performs pulse distance measurement. If the delay time measuring circuit 17 is provided for at least one photoelectric conversion cell 6a. Good.

Next, the operation of the measuring machine of this embodiment will be described.

First, the pulsed light sent from the pulse laser diode 1 is emitted from the objective lens 8. At this time, the lens 2 is driven by the motor 3 so that the spread angle of the pulsed light from the objective lens 8 is maximized. The emitted pulsed light is reflected by the object 9 to be measured, passes through the objective lens 8, is reflected by Haarmyla-4, passes through the lens 5, and reaches the light receiving device 6.

If the light receiving device 6 cannot detect the pulsed light at this time, the following causes are considered. Firstly, the subject is not sufficiently focused, secondly, the distance to the measuring object is too long and the amount of received light is below the detection level, and thirdly, the measuring object 9 is within the search range. It is possible that there is no such thing.

In the first case, the search is performed while the motor 7 moves the focal point of the lens 5 from a short distance to a long distance. In the second case, the search is performed while the motor 3 narrows the spread angle of the lens 2. Usually, both the first case and the second case are considered to be related, but in such a case, the maximum received light spreads because the received light amount is approximately inversely proportional to the square of the spread angle and the square of the distance. Assuming that the maximum measurement distance when the angle is set is known, this is considered as a system in which the flat area of the search range is fixed when searching for a long distance, and it is possible to respond by driving the divergence angle and the focus at the same time. it can.

FIG. 3A is a diagram for explaining the relationship between the spread angle and the distance at which the amount of received light is the same, and the maximum spread angle with respect to the distance d ₁ is θ ₁ . Here, it is assumed that θ ₁ coincides with the maximum divergence angle that can be physically maximized in the system. Further, the spread angle that can be the same as that when the amount of received light at the distance d ₂ is d ₁ is defined as θ ₂ . Figure 3 (b)
And FIG. 3C shows the maximum search areas at the distances d ₁ and d ₂ , respectively, and the diameters thereof are l ₁ and l ₂ , respectively. Although it is affected by humidity and temperature, it is generally l ₁ = l ₂ . In other words, it is possible to search in the same area for a distance of d ₁ or more, and it can be said that it is a search mechanism with a fixed flat area. In a system that requires focus matching, the focus, that is, the distance of the search surface is moved. However, the maximum volume can be searched by controlling the spread angle.

In the third case (when the measuring object 9 is not within the search range), the first processing is performed while the processing in the first and second cases described above is used together or the spread angle is fixed.
While using the processing in the case of 1), it is necessary to drive the surveying instrument main body or to deflect the emitted pulsed light, but the range to be driven becomes shorter than the conventional method. When the depth of focus is deep, the processing in the first case can be reduced or deleted.

Further, even if there is a slight defocus, it is possible to perform pulse distance measurement as long as the amount of received light that can detect the pulsed light can be obtained. It is also possible to build a system that performs precise focus matching.

As described above, the pulsed light can be detected.

Next, based on the position information obtained by the light receiving device 6 in which the photoelectric conversion cells 6a are two-dimensionally arranged in the package, the surveying instrument main body is driven by an electric motor (not shown) to measure the object to be measured. Collimate so that the optical axis of the object 9 is aligned.

Further, the lens 2 is driven by the motor 3, and the divergence angle is set so as to be a search range convenient for the tracking operation in consideration of the distance information.

Focusing, collimation, and fine adjustment of the search range are performed again.

By the above operation, focusing and collimation are automatically performed, and a system capable of automatic tracking can be constructed.

Since the surveying instrument of this embodiment does not require the use of an extra large component such as a TV camera, it can be miniaturized. Further, since the search range can be easily changed, it is possible to deal with the measurement object 9 that moves at a high speed by expanding the search range, and when there are a plurality of targets that can be measurement objects, the search range can be increased. It can be dealt with by narrowing. The emitted pulsed light is inversely proportional to the square of the divergence angle, but since the laser pulse diode 1 of the light source has a high output, the divergence angle from the objective lens 8 can be made large, and as a result, the measurement target 9 at a short distance can be obtained. At the time of collimation, it is possible to instantly collimate by simply pointing the surveying instrument main body at the measurement object 9. Conversely, by narrowing the divergence angle, a large amount of light can be obtained with respect to a long distance. Since a large amount of light is unnecessary at a short distance, a wide divergence angle can be obtained, and at a long distance, even a small divergence angle does not narrow the search range area itself, so that the amount of light can be prioritized.

In this embodiment, a case where a convex lens is used as the lens 2 has been described, but a concave lens may be used. The wide angle can also be controlled by a method of driving the laser pulse diode 1 directly along the optical axis with the motor 3, and in this case, the lens 2 becomes unnecessary.

Further, in this embodiment, the optical path for transmitting the pulsed light and the optical path for receiving the pulsed light are the same, but both optical paths may be separated.

[0036]

As described above, according to the surveying instrument of the invention described in claim 1, since the pulsed light generating means is used as the light source, the output can be increased to facilitate the long distance search. Further, since the light receiving surfaces of the plurality of light receiving means are two-dimensionally arranged, the position of the measuring object can be detected, and the focus detection by the contrast method can also be performed.

According to the surveying instrument of the second aspect of the present invention, it is possible to widen the search range for an object to be measured at a short distance to enable high-speed position detection and become an object to be measured at a short distance. When there are a plurality of targets, the object to be measured can be limited by narrowing the search range.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a surveying instrument according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of photoelectric conversion cells of a light receiving device.

Maximum search area relationship, and at a distance d _1, d ₂ and FIG. 3 is a distance d _1, d ₂ and the spread angle of the outgoing pulse light theta ₁ which the amount of light received by the light receiving device are the same, theta ₂ FIG.

FIG. 4 is a diagram showing information from a photoelectric conversion cell of a light receiving device as C
It is a circuit diagram for processing by PU.

[Explanation of symbols]

 1 pulse laser diode 2,5 lens 3,7 motor 6 light receiving device 6a photoelectric conversion cell 8 objective lens 9 object to be measured

Claims (1)

[Claims] 1. A pulsed light generating means for emitting pulsed light to an object to be measured, a light receiving means for arranging a light receiving surface two-dimensionally and converting reflected pulsed light from the object to be measured into an electric signal, said pulse A condensing optical system for converging the pulsed light from the light generating means, and a pulsed light divergence angle control means for controlling the divergence angle of the pulsed light from the condensing optics according to the distance to the object to be measured. The automatic collimation device of the surveying instrument.