Laser range finder for large ranges of measurement with a special receiver

#The invention relates to laser range finders that are based on the principle of measuring a pulse transit or phase transit time.

#Laser range measuring devices that are known in the prior art are based on measuring the transit time of the pulse or the transit time of the phase that can be distinguished from one another by a basic arrangement of the transmitting and receiving channels. This occurs by dividing these range finders in devices wherein the transmitting channel is arranged next to the receiving channel. Thus, the optical axes of these channels extend parallel to each other with a defined spacing from each other. These devices have transmitting and receiving channels that are arranged coaxially with each other, so that their optical axes coincide.

#In the measurement of objects, the optical “cross talk” of the receiver which can be caused, by back scatter of dust articles at close range, can be optically reduced only by two measures: by reducing the receiver surface and by increasing the axial spacing between the transmitting channel and the receiving channel.

#In the drawings wherein similar reference characters denote similar elements throughout the several views:

#FIG. 1.1 shows a sketch of the optical principle for a laser range finding device comprising a photodiode chip array determined by a two-hole shutter;

#FIG. 1.2 is a representation of a photodiode chip array with a two-hole shutter;

#Referring in detail to the drawings, the basic structure of the range finding device described in the following with the help of FIG. 1.1 is common to all of the following exemplified embodiments.

#The range finding device comprises a transmitting channel with a transmitting lens 1 and a laser light source 2, which is arranged in the focal point of transmitting lens 1. A receiving channel comprising a receiving lens 3 and a photodiode chip array arranged in the focal plane of receiving lens 3 is present parallel with the transmitting channel with a spacing “a” (equal to the spacing between the optical axes of the transmitting and receiving lenses).

#The beam emitted by laser light source 2 is collimated via transmitting lens 1, which impacts the object to be measured, and is then reflected by the object. The radiation impacting receiving lens 3 creates a receiving current IE, which is the receiving signal, depending on the distance of the object and the concrete design of the photodiode chip array in the given case.