Deutsche Forschungsanstalt Fur Luft-und Raumfahrt E.v.

Helmut Dietl

Volker Tank

Peter Haschberger

Oliver Mayer

Erwin Lindermeir

Franz Lanzl

Rainer Thiessen

Erwin Lindermeier

A method for measuring and determining a rotation angle of a rotating object in which a clock track corresponding to a desired angular resolution is applied on a magnetic, optical or optomagnetic storage medium. The storage medium is then rotated synchronously with the rotating object, and during the operation a pulse sequence corresponding to the clock track is read from said storage medium. The read pulse sequence is then supplied for further processing to following electronics in which the actual rotation angle is firstly stored in a FIFO memory and secondly directly available for further uses. Furthermore, the invention provides an apparatus for measuring and determining a path difference in Michelson interferometers in which path difference are generated via a rotary movement, for example of a rotating retroreflector. A memory medium is rigidly connected to the rotation shaft of the rotating retroreflector generating a path difference and on said medium a clock track corresponding to the sampling theorem is applied and during the rotation movement is read by a read head fixedly associated with the storage medium. During operation said pulse sequence is read by the read head and supplied to following signal electronics in which from the pulse sequence the desired clock pulse and thus the path information is then obtained.

Method for measuring and determining a rotation angle of a rotating

A method and an apparatus are provided for calibrating a spectrometer, in particular a Fourier transform spectrometer (FTS), in particular for the infrared spectral range. At least four black body radiators of different temperatures are provided, which are arranged horizontally, i.e. parallel to the surface of the earth, thereby avoiding temperature gradients due to convection. The temperature of the at least four radiators is determined by means of the calibrating method without a separate measurement. In the method according to the invention, at the same time the absorption of the atmosphere is considered as a characteristic of the spectrometer, thereby eliminating separate measurement and correction thereof. In addition, for Fourier transform spectrometers the calibration is carried out by means of complex spectra.

Method and apparatus for calibrating spectral radiometers

A method and an apparatus are provided for determining a path difference in a Michelson interferometer which comprises at least one reciprocably moving mirror element and an analog to digital converter, and which is provided for the determination of an electromagnetic spectrum without a laser having to be permanently used for that purpose. On the contrary, magnetic, optical and optomagnetical storage media are arranged parallelly to the travel path of the mirror element of the interferometer. A clock track is written on the storage medium in accordance with the sample theorem. In operation a pulse sequence derived from the clock track is read by a read head mounted on the movable mirror element and the desired clock pulse and thus the path information is derived therefrom.

Method and apparatus for determining a path difference in a Michelson

An optical interferometer used for measuring the rotational angle or the anglular position of a rotating object, in which a path deflection is caused by means of the rotation of a reflector, the rotational movement of which is coupled with that of the object to be measured and thus is synchronous with its rotation. Furthermore, a laser beam is introduced into the interferometer. The path deflection caused by the rotation of the retro-reflector creates in the introduced laser beam varying interferences of defined wave length, which are proportional to the rotational angle of the reflector and of the object to be measured which drives it. Furthermore, the angular resolution is inversely proportional to the wave length of the laser beam.

Device for measuring the angle of rotation or of the angular position of

In a Michelson interferometer for producing optical path differences, from a beam divider, a deflection mirror, an externally silvered corner mirror, a collective lens and a radiation detector an input/output module is formed, from two rotating retroreflectors and two stationary retroreflectors an intermediate module is formed, and from two further rotating retroreflectors and from a bilaterally silvered plane-parallel plate a termination module is formed. The three modules can be combined to an interferometer in such a manner that the plane mirrors of the corner mirror of the input/output module are each arranged opposite a respective input-side half of the two rotating retroreflectors of the intermediate module and between said reflectors which in turn are arranged directly next to and adjacent the two further rotating retroreflectors of the termination module in such a manner that the output-side aperture halves of the two stationary retroreflectors are aligned opposite the input-side aperture halves of the two further rotating retroreflectors of the termination module. In operation the respective adjacent rotating retroreflectors of the modules fixedly connected to each other in exact match rotate in-phase with respect to their rotational angle position and in opposite phase of 180.degree. with respect to the corresponding opposite retroreflectors.

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Munich, Germany

Helmut Dietl