Title: Calibrating device for light scatter photometering instrument

Abstract: A flat sandwich composite plate of nested wedge-shaped sheets of highly transparent and gray neutral density filter glasses is enclosed in a frame. A bracket on the frame mounts it on the carriage of an optical instrument which measures the light scattering characteristics of a series of samples traversed on a carriage past a photometering station. A surface of the composite plate has a mat finish which scatters the light passing through it. The density and thickness of the filter glass are arranged to cover a predetermined range of light scatter corresponding to that caused by the range of samples which the optical instrument can accurately measure. An appended flat section of filter glass provides light scatter characteristics corresponding to an auxiliary sample characteristic. The transmittance of the appended section is adjusted by a movable leaf and notched adjusting segments. The mat surface is obtained by frosting a surface of the filter glass by blasting or grinding with 9 micron grit. The neutral density filter glass has a flat spectrum characteristic obtained by doping with carbon.

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Inventors: Longhenry, David K. (East Lyme, CT, US)

Application Number: 547012
Filing Date: 1975-02-04
Publication_date: 1976-03-09
Assignee: Pfizer, Inc. (New York, NY)
Primary Class(es): 356/234 356/243.2, 356/243.8, 356/244, 356/338
Other Classes:
US Patent Ref:

1419725	Jun, 1922	Fisher	350/314.
2244507	Jun, 1941	Thomas	350/314.
2682801	Jun, 1954	Davidson et al.	350/314.
3381572	Jul, 1968	Tvwiner	350/314.
3418484	Dec, 1968	Harmon	350/314.
3627424	Dec, 1971	Dorman et al.	356/103.
3832532	Aug, 1974	Praglin et al.	356/81.

Other Refs:
Primary Examiner: Smith, Alfred E.
Assistant Examiner: Henry, Jon W.
Attorney: Connolly and Hutz