The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 17, 2009
Filed:
Dec. 14, 2004
Siegbert Steinlechner, Leonberg, DE;
Siegbert Steinlechner, Leonberg, DE;
Robert Bosch GmbH, Stuttgart, DE;
Abstract
A method for triggering a heterodyne interferometer having two acousto-optical modulators in separate light paths, a receiver generating an analog signal and a downstream A/D converter converting the analog signal into a digital signal is described. The one acousto-optical modulator is triggered at a modulation frequency fand the other acousto-optical modulator is triggered at another modulation frequency f, the difference between modulation frequencies fand fforming a heterodyne frequency fand the analog signal being converted into the digital signal in the A/D converter at sampling frequency f. In such a heterodyne interferometer, a fixed ratio of modulation frequencies is maintained, and they are prevented from shifting due to aging and drift by forming at least two of the frequencies of modulation frequencies f, fand sampling frequency ffrom a fundamental frequency fof a common oscillator. As a result, it is also possible for sampling frequency fto be in a fixed phase ratio to the differential frequency of modulation frequencies f, f, of heterodyne frequency f. Measurement accuracy is increased because sampling is performed at a constant phase, independently of drift and aging.