Method and apparatus for measuring the absolute thickness of dus

Details Method and apparatus for measuring the absolute thickness of dus Method and apparatus for measuring the absolute thickness of dus

1986-06-05

1989-03-28

Willis, Davis L.

Optics: measuring and testing

By dispersed light spectroscopy

Utilizing a spectrometer

364525, G01B 902

Patent

active

048158569

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.

REFERENCES:
patent: 3612692 (1971-10-01), Kruppa et al.
patent: 3664739 (1972-05-01), Pryor
patent: 3720471 (1973-03-01), Kasahara et al.
patent: 3744912 (1973-07-01), Williams et al.
patent: 3788746 (1974-01-01), Baldwin et al.
patent: 3816649 (1974-06-01), Butters et al.
patent: 3869211 (1975-03-01), Watanabe et al.
patent: 3930730 (1976-01-01), Laurens et al.
patent: 3943278 (1976-03-01), Ramsey, Jr.
patent: 3957376 (1976-05-01), Charsky et al.
patent: 3994599 (1976-11-01), Southwell
patent: 4180830 (1979-12-01), Roach
patent: 4221486 (1980-09-01), Jaerisch et al.
patent: 4293224 (1981-10-01), Gaston et al.
patent: 4329058 (1982-05-01), James et al.
patent: 4330213 (1982-05-01), Kleinknecht et al.
patent: 4377343 (1983-03-01), Monson
patent: 4443106 (1984-04-01), Yasuda et al.
patent: 4453828 (1984-06-01), Hershel et al.
patent: 4618261 (1986-10-01), Flanders et al.
Tabouda et al., "Rectangular Grid Fringe Pattern for Topographic Applications", Applied Optics, 3/1976, pp. 597-599.
Robert A. Bruce et al. "Scanning Absolute Thickness of the Protective Overcoat Layer on Spinning Optical Disks", Digest of Technical Papers, pp. 56-57, Conference on Lasers and Electro Optics (OSA/IEEE) San Francisco, CA, Jun. 9-13, 1986.

Affiliated with

Also associated with

Rating

Method and apparatus for measuring the absolute thickness of dus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method and apparatus for measuring the absolute thickness of dus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for measuring the absolute thickness of dus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1655139