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:
Sep. 06, 1983
Filed:
Dec. 03, 1980
Michel Lacombat, Paris, FR;
Thomson-CSF, Paris, FR;
Abstract
Optical system for the automatic alignment of two motifs in which the alignment marks of a first fixed motif forming the reference are constituted by at least one pair of identical periodic optical gratings with a constant spacing P and having a predetermined distance d.sub.X from one another such that the equation d.sub.X =(n+.epsilon.) P is proved, n being an integer and .epsilon. a fraction of unity. An optical modulator, for example electro-optical means incorporating a Pockels cell alternately illuminate with the timing of the high frequency control signals, the said gratings in windows, whose position can be regulated in accordance with a given axis. The image of these windows is projected onto gratings carried on a second moving support to be aligned and produces orders of diffraction. An optoelectronic detector detects a predetermined order of diffraction. The high frequency-modulated output signals are transmitted to control circuits for producing the automatic alignment.