Leica Geosystems Ag

Kern & Co. Ag

Leica Ag

Dietrich Meier

Thomas Jensen

Bernhard Braunecker

Roland Zumbrunn

Hans-Ulrich Minder

Thomas Luethi

Werner Schertenleib

An electro-optical distance-measuring unit () includes a light source (), the emitted light of which in the distance-measuring unit () is guided onto a measurement path () at least by one polarizing beam splitter (), an electro-optical modulator () and a retarder (). Light that is returned along the measurement path () is guided at least by the retarder (), the electro-optical modulator () and the polarizing beam splitter () onto a detector (). The distance-measuring unit () furthermore includes a control and evaluation unit () for determining a length of the measurement path () in accordance with a modulation frequency of the electro-optical modulator () and a signal of the detector (). The light source () has a broad spectrum of the emitted light and is preferably a super-luminescent diode.

Electro-optical distance-measuring unit

An angle measuring device for optical angle measurement has a telescope bodywhich is rotatably mounted around at least one shaft (), wherein the shaft () is rotatably mounted at least two bearing points, and the bearing pointsare at a distance from one another in the direction of the shaft (). In this case, at least two sensor arrangements for detecting the position of the shaft () are respectively arranged at a measurement point along the shaft (), wherein the measurement points are at a distance from one another in the direction of the shaft (). At least one of the sensor arrangements has a group of capacitive sensors () which detect a displacement of the shaft () in directions perpendicular to the axial direction at the measurement point.

Angle measuring device

A coordinate measurement instrument includes an optical distance measurement device () for measuring the distance from an auxiliary measurement means () which can move in space, a zoom camera (), which can rotate with respect to at least two axes, with a zoom lens, and an overview camera () for coarse localization of the auxiliary measurement means (). A light exit and light receiving optical system () of the distance measurement device (), the zoom camera () and the overview camera () are arranged on a shared carrier () which can rotate with respect to at least two axes (A, Z). The optical axis () of the distance measurement device () and the optical axis of the overview camera (), preferably extend coaxially outside the coordinate measurement instrument. Sub-units of the distance measurement devices () are, preferably, arranged on the carrier () and on the rotatable intermediate unit () and are connected to each other by means of optical waveguides (-).

Coordinate measurement instrument

In a method and a measuring device () for measuring an absolute distance value corresponding with a range () between a measuring device () and a target (), wherein for measuring the absolute distance value a number of individual measuring steps are performed with an absolute distance meter (), a distance variation between the measuring device () and the target () is also measured with a relative distance meter () at least approximately simultaneously with these individual measuring steps and the distance variation is taken into account as the absolute distance is being determined. Preferably an iterative method comprising several sampling steps is used for measuring the absolute distance, e.g. according to the Fizeau method, wherein an output value (A) is generated from an input value (f, f, f, . . . ) and measured in each sampling step. The output value (A) is dependent on the input value (f, f, f, . . . ) and on the distance.

Method and measuring device for measuring an absolute distance

A method for the frequency stabilization of a gas laser with a laser tube (), in stable operation includes a continuous operation control procedure with the following steps: During a startup phase, the procedure includes the following steps:

Frequency stabilised gas laser

In a laser tracking system equipped for interferometric distance measurement there are provided at least two retroreflectors ( ) which are connected to the target tracking mirror ( ) in a manner such that their position changes when the spatial orientation of the target tracking mirror ( ) is changed. Secondary measurement beams ( ) deflected out of the primary measuring beam ( ) of the laser tracking system are directed onto the retroreflectors ( ). Path length changes in the beam path of the secondary measurement beams ( ) are interferometrically measured and the readings are used for computing the spatial orientation of the target tracking mirror ( ).

Method for detecting the spatial position of a tracking mirror and a mirror arrangement for carrying out said method

Measuring ball reflector

Electro-optical measuring device for absolute distances

Device for holding a cylindrical laser tube in a stable radiation

To simplify the reflectors for electro-optical distance measurement with a distance measuring apparatus with modulation of light outside of the light source, the optical bundle for distance measurement is focussed on to the target. Thereby, distance measurements on unprepared (non-cooperative) objects or on objects prepared only with simple reflecting foils are made possible.

Method and apparatus for electro-optical distance measurement

For electrooptical measurement of distance with modulation of light external to the light source (1) a modulator system (5, 7, 8, 11) with low sensitivity to temperature and with a low modulating voltage is disclosed. The temperature dependence of the static birefringence of a modulating crystal (7) is compensated by passing the modulated light beam (6), after traversing the crystal (7), a quarterwave plate (11), the measured path (9) and the quarterwave plate (11) again--a second time through the crystal (7) with its polarization rotated by 90.degree.. The light beam returning from the measured path is separated from its source (1) by means of a polarizing beam splitter (5).

Electrooptical distance measuring apparatus

With an electrooptical distance meter impulses of light are transmitted over the distance. The distance is found by counting the duration of gating signals which last between transmission and reception of the light impulses. 10,000 times of travel generated by a first digital circuit (16, 17, 18) are communicated to a second digital circuit (1, 19, 20) for storing and processing. The distance is computed by the second circuit (1, 19, 20) by forming a mean value from the more frequent counts. By evaluation of artificial gating signals of various durations and by generation of gating signals from the light impulses by means of various threshold levels an improved accuracy of distance measurement is achieved, even when measuring on natural, non cooperative objects.

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Niedererlinsbach, Switzerland

Dietrich Meier