Laser telemeter

Details Laser telemeter Laser telemeter

1999-07-02

2001-12-11

Buczinski, Stephen C. (Department: 3662)

Optics: measuring and testing

Range or remote distance finding

With photodetection

C356S028500

Reexamination Certificate

active

06330056

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a laser telemeter having separate transmitting and receiving optical systems, and at least monocular target observation.
2. Description of the Related Art
The majority of the known laser telemeters are based on the following principle. A collimated laser beam is produced and is directed via a transmitting optical system at a remote target. The laser light reflected by the target is picked up by the receiving optical system and fed to a detector. The receiving optical system is usually also used for target observation. Such a device is disclosed, for example, in German Publication DE 41 35 615 A1. A binocular observation device with a laser telemeter is disclosed in German Publication DE 37 04 848 A1.
Particularly in the case of small targets, it is necessary to collimate the laser beam well. It is desirable for the distance-dependent size of the laser spot to be smaller than the cross-section of the target to be measured, in order both to achieve very high laser light intensity on the target and to selectively influence the transmitted beam by the target to be measured.
The optical parameters of the transmitting optical system determine the divergence of the transmitted beam. The intensity of the laser light arriving at the detector and reflected by the target depends on the optical parameters of the receiving optical system, essentially on its diameter. The optical parameters of the transmitting and receiving optical systems therefore directly influence the maximum range of the laser telemeter.
An increase in the range can be achieved either by increasing the laser power or by making the transmitting and receiving optical systems larger. The maximum laser power is limited on the one hand by regulations relating to safety for the eyes and moreover by the capacity of the energy source for operating the laser. The disadvantages of increasing the dimensions of the optical systems are the associated inconvenience of handling and greater weight.
The technical complexities associated with a larger range have led to the development and optimization of specially designed laser telemeters for different ranges. The users of such devices must therefore decide on different devices depending on the measuring range required and may have to acquire several devices.
The readiness of the devices for use additionally depends on the weather conditions, which may hinder the transmission of the optical radiation. A device designed for relatively long ranges may, under unfavorable circumstances therefore, also be used for shorter distances at which the device designed for these ranges has failed. However, the disadvantage is that only the limited field of view designed for more remote targets is constantly available for the target observation. In case of doubt, the users will nevertheless have to decide in favor of the technically more complex, and therefore more expensive, device.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a laser telemeter which permits the range to be increased in an economical manner, especially for small targets, without substantially impairing the convenience of handling and safety for the eyes.
This object is achieved, according to the invention, by a laser telemeter comprising a transmitting optical system; a receiving optical system; a target observation system; a first telescope optical system before the transmitting optical system; and a second telescope optical system before the receiving optical system. The first telescope optical system reduces divergence of a transmitted beam. The second telescope optical system has an aperture angle adapted to divergence of said transmitted beam
The laser telemeter according to the invention may have a numerical aperture of each of the first and second telescope optical systems adapted in each case to a respective transmitting or receiving optical system.
The magnification of the first and second telescope optical systems may be the same.
The laser telemeter may further comprise a common support frame for the first and second telescope optical systems coupled to the laser telemeter.
The target observation system may be monocular or binocular.
Each telescope optical system may further comprise either a positive lens on an object side and a negative lens on an image side or, alternatively, a positive lens on each side.


REFERENCES:
patent: 4733961 (1988-03-01), Mooney
patent: 5221956 (1993-06-01), Patterson et al.
patent: 5552879 (1996-09-01), Takamiya et al.
patent: 37 04 848 A1 (1988-03-01), None
patent: 41 35 615 A1 (1993-05-01), None
patent: 198 29 659 C1 (1998-07-01), None

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