JPH0330115B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a light wave distance measuring device in which the objective lens of the collimating optical system is also used as a light wave distance measuring optical system, and in particular, to The present invention relates to a coaxial type light wave distance measuring device using the other semicircular side for receiving light.

(Background of the Invention) Conventionally, various light wave distance measuring devices have been known in which the objective lens of the collimating optical system is also used as a light wave distance measuring optical system.
Various types of light wave ranging optical system configurations have been put into practical use. In order to maintain high distance measurement accuracy, it is of course necessary to prevent noise light from being mixed into the received light, but it is also necessary to precisely align the transmitting optical path and the receiving optical path. The manufacturing, assembly, and adjustment involved great difficulties. Further, in order to facilitate adjustment, it is possible to provide a dedicated member for each optical system, but this does not require a complicated structure and tends to increase the size of the overall device structure.

(Object of the Invention) An object of the present invention is to provide a light wave distance measuring device that has excellent distance measuring accuracy, is easy to assemble and adjust, and has a simple configuration.

(Summary of the Invention) The present invention has a collimating optical system in which an objective lens, a focusing lens, and an eyepiece are sequentially arranged, and an optical path splitter disposed between the objective lens and the focusing lens; A transmitted light reflecting member and a received light reflecting member are integrally arranged on the optical axis of the objective lens in an optical path branched by the optical path splitter, and a light source that supplies transmitted light to the transmitted light reflecting member; In a coaxial light wave ranging device having a light receiving member that receives a light beam from a received light reflecting member, between the optical path splitter and the transmitted light reflecting member and the received light reflecting member that are integrally arranged, By arranging an auxiliary lens, the objective lens and the auxiliary lens form an afocal system, and the reflecting surfaces of the transmitted light reflecting member and the received light reflecting member are perpendicular to each other. .

(Examples) The present invention will be described below based on Examples. FIG. 1 is an optical path diagram showing the configuration of an embodiment of a light wave distance measuring device according to the present invention. An objective lens 1, a focusing lens 2, an erecting prism 3, a focusing plate 4, and an eyepiece 5 are arranged in this order to constitute a collimating optical system. An optical path splitter 6 having a dichroic mirror surface for reflecting infrared light and transmitting visible light is arranged between the objective lens 1 and the focusing lens 2.

The optical path splitter 6 consists of a right-angle prism P1 and a trapezoidal prism P2 that are bonded together with a slope D as a dichroic mirror surface, and the optical axis A of the objective lens 1
It has an entrance surface 6a perpendicular to the incident surface 6a, and a first exit surface 6b parallel thereto. The dichroic mirror surface D, which is a semi-transparent mirror surface, has the function of reflecting infrared light and transmitting visible light at the same time, and the infrared light reflected here is totally reflected by the incident surface 6a, and then passes through the trapezoidal prism. The light passes through the second exit surface 6c corresponding to the slope of P2. Therefore, visible light for collimation is emitted from the first exit surface 6b, and infrared light for distance measurement is emitted from the second exit surface 6c.

Here, the incident angle θ of the dichroic mirror surface D
That is, the angle between the optical axis A of the objective lens 1 and the normal to the dichroic mirror surface D is determined as follows.

First, regarding the lower limit of θ, in order to make the optical path splitter compact, the incident light flux from the objective lens 1 and the reflected light flux from the dichroic mirror surface D must be superimposed on the entrance surface 6a of the optical path splitter. Therefore, the entrance surface must be a transparent total reflection surface, not a mirror surface. Therefore, subject to the restriction of the critical angle at the incident surface 6a, when the refractive index of the prism P2 is n, it is necessary to satisfy the condition θ>1/2·arcsin1/n (1). At the same time,
When θ is small, the optical path of the ranging light emitted from the optical path splitter 6 becomes close to parallel to the optical axis of the collimating optical system. This makes it difficult to arrange the distance measuring optical element group including the lens 12 and the like.

On the other hand, regarding the upper limit of θ, as θ increases, the thickness in the optical axis direction of the optical path splitter for branching the optical path of the ranging optical system from the optical path of the collimating optical system, that is, the thickness of the incident surface 6a and the first exit The distance from the surface 6b increases, making the collimating optical system longer. In addition, the point Q where the optical axis of the ranging optical system reflected by the dichroic mirror surface D intersects with the entrance surface 6a, which is a total reflection surface, is the optical axis of the collimating optical system as θ increases and approaches 45 degrees. Since the second prism P2 becomes larger, the entire device becomes larger. Furthermore, as is well known in thin film technology,
If the incident angle θ becomes large, the characteristics of the dichroic mirror deteriorate, so the incident angle cannot be made very large, and manufacturing becomes difficult.

From the above viewpoint, it is desirable that the angle θ between the normal line of the dichroic mirror surface D and the optical axis of the objective lens be set in the range of 15°<θ<45°. In this embodiment, a configuration in which θ is 30 degrees is adopted.

Now, a negative lens 7 as an auxiliary lens is provided on the optical path of the distance measuring optical system branched by the optical path splitter 6 made of a prism having a dichroic mirror surface as described above.
A so-called Galileo-type afocal system is formed with this negative lens. Therefore, objective lens 1
A beam of light from an object at an infinite distance entering the lens 7 becomes a parallel beam of light after exiting the lens 7. On the optical path of such a parallel light beam, a transmitted light reflecting member 8 for reflecting the transmitted light and a received light reflecting member 9 for reflecting the received light are provided with the optical axis A as a boundary. The transmitted light reflecting member 8 has an entrance surface 8a and an exit surface 8b that are orthogonal to each other, and a 45-degree slope 8c is a silver-deposited back mirror that has high reflectance in the infrared region and visible region. It is sufficient for this reflective surface to reflect only the infrared region for light wave distance measurement, but it is more convenient to make adjustments in the visible range for manufacturing adjustments. It is also effective to increase the reflectance of The transmitted light reflecting member 8 is joined and supported by a 45-degree first inclined surface 9a formed on the received light reflecting member 9 by an inclined surface 8c. The received light reflecting member 9 has a first slope 9a.
A second slope 9b is formed on the surface reflecting surface at an angle of 45 degrees in the opposite direction to that of the surface mirror. It is formed as. The optical path of the transmitted light and the optical path of the received light by both reflecting members are configured to be perpendicular to the optical axes of the objective lens 1 and the negative lens 7, and are located on the same straight line.

The transmitting light optical path and the receiving light optical path, which are branched from each other by the transmitting light reflecting member 8 and the receiving light reflecting member 9, still maintain a parallel light flux, and the transmitting positive lens 11 is provided in the transmitting light optical path, and the receiving light optical path is A receiving positive lens 12 is arranged in each optical path. A light emitting diode 10 as a light source is provided on the focal point of the positive transmission lens 11, and a photodiode 13 as a light receiving member is provided on the focal point of the positive receiving lens 12. Here, a transmission optical path of the ranging optical system is formed by the light source 10, the transmission lens 11, the transmission light reflection member 8, the negative lens 7, the optical path splitter 6, and the objective lens 1. The lens 7, the received light reflecting member 9, the receiving lens 12 and the light receiving member 13 form a receiving optical path of the distance measuring optical system. Further, a reference light optical path is formed by an optical path that directly reaches the light receiving member 13 from the light source 10 via the transmitting lens 11 and the receiving lens 12. In this embodiment, the inclination angles of the respective reflecting surfaces of the transmitted light reflecting member 8 and the receiving light reflecting member 9 were both set to 45 degrees with respect to each incident surface, but the angle is not limited to this angle. As long as the reflective surfaces of the members are perpendicular to each other, the optical axes of the transmitting lens 11 and the receiving lens 12 can be aligned on the same straight line. Since it can be shared, there is no need to provide any dedicated member as a reference light optical path, and the configuration can be extremely simple.

In the basic configuration of such a distance measuring optical system, a background light cut filter 14 is provided between the received light reflecting member 9 and the receiving lens 12 to cut out light of wavelengths other than the received light that enters as noise. is located. In order to switch between the transmission light and the reference light, an optical path switch 15 is rotatable about a rotation axis eccentric from the optical axis of the transmission lens.
is provided between the light source 10 and the transmitting lens 11, and a rotary filter 16 is provided between the receiving lens 12 and the light receiving member 13 to equalize the intensity of the received light and the reference light.
is established between. In addition, the objective lens 1
A light shielding plate 17 is provided along the optical axis of the negative lens 7. The light shielding plate 17 is shown in FIG. 2A.
As shown in the side view of FIG. 2B and the plan view of FIG.
is formed at the bent portion to prevent the light beam near the optical axis from entering the receiving optical path.

between the transmitting lens 11 and the negative lens 7, between the negative lens 7 and the receiving lens 12, and between the transmitting lens 11
The parallel system between the receiving lens 12 and the receiving lens 12 has the following advantages.

First, in general, regarding transmission optical systems, assuming that the size of the light source is constant, the shorter the focal length of the transmission optical system as a whole, the larger the transmission angle, which widens the allowable range for distance measurement. In the configuration of the present invention, the transmitting lens 11
By changing the focal length of the transmitting optical system, the focal length of the transmitting optical system as a whole can be shortened without significantly changing the total length of the transmitting optical system, and there is a high degree of freedom in explaining the basic configuration. Second, since the ranging light is infrared light, it is necessary to remove the background light cut filter 14 when adjusting the ranging optical system, but the background light cut filter 14 is placed in the parallel light beam. Therefore, there is no focus shift or optical axis shift due to insertion and removal of this filter, and it is possible to perform sufficient adjustment for infrared light through visible light observation. Furthermore, since the light beam incident on the background light cut filter is neither convergent nor diverging, there is no risk of being adversely affected by the angular characteristics of the multilayer thin film forming this filter. Thirdly,
Since the optical path of the reference optical system is shared by a part of the transmitting optical system and a part of the receiving optical system, the structure is simple and does not require a dedicated member as the reference optical system. Since the member 13 is disposed on the same optical axis, adjustment can be made extremely easily and accurately.

If the light source and the light receiving member are arranged on the same straight line, and also on the same plane as the plane containing the optical axis of the collimating optical system, the collimating optical system and the distance measuring optical system Even if the collimating telescope is configured integrally, the width direction of the collimating telescope barrel will not be increased, and there are no restrictions on configuring the collimating telescope to be rotatable in the vertical plane relative to the main body of the device, similar to a general theodolite. Not.

In the above embodiment, the light source was provided at the focal position of the transmitting lens 11, and the light receiving member was provided at the focal position of the receiving lens 12, but instead of placing the light source and the light receiving member directly at each focal position, an optical fiber Needless to say, it can be configured to guide each luminous flux.

(Effects of the Invention) As described above, according to the present invention, the important elements of the distance measuring optical system, such as the light source, the light receiving member, the transmitted light reflecting member, and the received light reflecting member, are integrated on the parallel optical path by the auxiliary lens. Since these element groups are arranged in parallel, it is possible to separate and independently assemble and adjust these element groups using the parallel light beam as a boundary. After that, these important elements can be attached to the main body, which has a collimating optical system including an objective lens, focusing lens, etc., an optical path splitter, and an auxiliary lens that have been assembled and adjusted separately, so each component It is possible to easily perform high-precision assembly and adjustment. Furthermore, since there is no need to provide a dedicated member as a reference light optical path for light wave distance measurement, the entire device can be made compact without complicating the configuration.

[Brief explanation of drawings]

FIG. 1 is an optical path diagram showing the configuration of an embodiment of a light wave distance measuring device according to the present invention, and FIGS. 2A and 2B are a side view and a plan view of a light shielding plate provided in the distance measuring optical system. [Explanation of symbols of main parts], 1...Objective lens,
2... Focusing lens, 5... Eyepiece lens, 6... Optical path splitter, 7... Negative lens, 8... Transmitted light reflecting member, 9... Receiving light reflecting member, 10... Light source, 11
...Transmission lens, 12...Reception lens, 13...
Light receiving member.

Claims (1)

[Claims] 1. A collimating optical system in which an objective lens, a focusing lens, and an eyepiece are sequentially arranged, an optical path splitter disposed between the objective lens and the focusing lens, and an optical path branched by the optical path splitter. A transmitted light reflecting member and a received light reflecting member are integrally arranged on the optical axis of the objective lens, and a light source that supplies transmitted light to the transmitted light reflecting member and a luminous flux from the received light reflecting member are arranged inside the objective lens. In the coaxial light wave ranging device having a light receiving member that receives light, an auxiliary lens is disposed between the optical path splitter and the transmitted light reflecting member and the received light reflecting member that are integrally arranged. The objective lens and the auxiliary lens form an afocal system, and the reflecting surfaces of the transmitted light reflecting member and the received light reflecting member are perpendicular to each other.