Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1992-03-12
1994-06-07
Turner, Samuel A.
Optics: measuring and testing
By particle light scattering
With photocell detection
356 45, 356349, G01B 902
Patent
active
053194390
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
a) Technical Field
The present invention is directed to a stationary wave interpolator in which two conductive paths are connected in each instance with a series connection comprising a photodiode, a hybrid amplifier and a double-hole core, in which the photodiode assigned to the first conductive path is provided for detecting the mode distance frequency of a laser and the photodiode assigned to the second conductive path is provided for detecting the mode distance frequency plus/minus the Doppler shift of an interferometer, in which the first conductive path is covered by an angle grid having a grid measurement which increases gradually and beginning with a starting angle and ending with an ending angle, and in which all component elements and connections are arranged on a carrier as dielectric material.
The invention is applicable in any measurement technique. It is useable in an advantageous manner particularly where high speeds of objects, e.g. rotational and translational movements at ultra-precision processing machinery, occur at high incremental resolutions.
b) Background Art
All known solutions for carrier frequency methods allow only a low object displacement speed, e.g. approximately 50 mm/s at .lambda./256, because of the low carrier frequency of the Zeeman He-Ne laser with approximately 2 MHz at high interpolation rates. Accordingly, resolutions of .lambda./1024 at an object displacement speed of 100 mm/s cannot be realized. Further, increasing the resolution by multiplying the carrier frequency involves a very high expenditure on circuitry (as demonstrated in U.S. Pat. No. 3,788,746), wherein no real-time processing is possible in rapid systems. Further, solutions are known in which disadvantageous transit time effects (delays) occur with reversal of direction of the object because of a control deviation of the phase regulating loop caused by hysteresis. Accordingly, it is not possible to increase the resolution in real-time processing, since an A/D signal conversion time (interpolation) leads to disadvantages (serial data evaluation).
SUMMARY OF THE INVENTION
The invention has, as a primary object, providing a stationary wave interpolator which enables a high resolution in real-time operation in rapid systems (parallel signal processing).
This object is met, according to the invention, in a stationary wave interpolator in that a plurality of double balanced mixers are connected by their reference input to a first conductive path, in that the reference input of a first double balanced mixer is guided so as to be localized at the location of the starting angle of the first conductive path, in that other double balanced mixers are connected to the first conductive path by their reference inputs so as to be localized at a distance of the increasing grid measurement until the ending angle, in that the double balanced mixers are connected to the second conductive path by their measurement input, and in that the outputs of the double balanced mixers are connected to a digital discriminator for decoupling a phase-shifted Doppler frequency. This provides the possibility of parallel evaluation, e.g. via ASIC. The double balanced mixers are preferably constructed as conventional hybrid networks which allow differential frequencies of two input frequencies to be transmitted.
The dielectric material is advantageously a ceramic work material.
In an advantageous further development of the invention, the conductive paths are constructed as arc-shaped strip lines which are divided into portions corresponding to the grid. The carrier also preferably has an arc-shaped cross section corresponding to the arc shape of the conductive paths.
The first conductive path should advantageously have a length corresponding to the value .lambda./2 of the mode distance frequency.
In the invention, at least two double balanced mixers are to be provided which are coupled with the first conductive path by their reference inputs in the grids and correspond to the angles 0.degree. and 90.degree.. H
REFERENCES:
patent: 3788746 (1974-01-01), Baldwin et al.
patent: 4566794 (1986-01-01), Hanse
Chour Matthias
Netzel Mario
Carl Zeiss Jena GmbH
Turner Samuel A.
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