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:
Mar. 28, 1989
Filed:
Jun. 05, 1986
Robert A Bruce, Morrison, CO (US);
Storage Technology Partners II, Louisville, CO (US);
Abstract
A method and apparatus for measuring the absolute thickness of dust defocus layers upon spinning optical disks utilizes a collimated, expanded beam of light from a helium-neon laser which is focused into a converging beam and directed towards the layer at a predetermined angle of incidence defined by an angular spread centered about the angle of incidence. A pair of divergent beams reflecting from the upper and lower surfaces of the layer are received by a collecting mirror and are recollimated by a collimating lens to be incident upon a self-scanning photodiode array. The divergent beams form a monotonic interference pattern having a fringe density which is proportional to the distance between the upper and lower surfaces, and which is determined by the photodiode array.