Title: Detection of blemishes in surfaces

Abstract: A detector of blemishes in a surface comprises a transmitting station from which a beam of light is caused to scan a moving surface to produce a raster pattern thereon. Light specularly reflected from, or transmitted by, the surface is collected at a receiving station after being diffused by a sheet of translucent material disposed in the path of this light. The diffused light in the receiving station is collected and directed by reflective surfaces towards a photodetector such that when the beam engages a blemish in the surface, the amount of light detected falls. The detector combines the sensitivity of collecting large amounts of specularly reflected light with a simple optical system associated with the collecting of diffused light.

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Inventors: Clarke, Graham Morley (Edinburgh, SC, US)

Application Number: 394980
Filing Date: 1973-09-07
Publication_date: 1976-01-06
Assignee: Ferranti, Limited (Hollinwood, EN)
Primary Class(es): 250/559.49 250/216, 250/559.17, 356/430
Other Classes:
US Patent Ref:

2806401	Sep, 1957	Demuth et al.	356/237.
3061731	Oct, 1962	Thier et al.	250/563.
3396281	Aug, 1968	Blackman	250/239.
3549264	Dec, 1970	Christie	356/210.
3572947	Mar, 1971	Sepall	356/239.
3675016	Jul, 1972	Blaisdell et al.	250/236.
3723747	Mar, 1973	Steele	250/239.

Other Refs:
Primary Examiner: Stolwein, Walter
Assistant Examiner:
Attorney: Cameron, Kerkam, Sutton, Stowell & Stowell