Optical refraction testing instrument


FIG. 1 is a perspective view of an optical refraction testing instrument, showing my new design.

FIG. 2 is a front elevational view thereof.

FIG. 3 is a top plan view thereof.

FIG. 4 is a side elevational view as taken from the left hand side of FIG. 2.

FIG. 5 is a bottom plan view thereof.

FIG. 6 is a rear elevational view thereof.

Referenced Cited
U.S. Patent Documents
D207675 May 1967 Hermann
D212647 November 1968 Minas
D213918 April 1969 Cohen
2283769 May 1942 Schwanzel
3778164 December 1973 Walker
Patent History
Patent number: D244483
Type: Grant
Filed: Apr 4, 1975
Date of Patent: May 24, 1977
Assignee: Nerthus, Inc. (Saratoga, CA)
Inventors: John E. Toth (San Diego County, CA), Victor L. Copeland (San Diego County, CA)
Primary Examiner: Bernard Ansher
Attorney: Carl R. Brown
Application Number: 5/565,110
Current U.S. Class: D24/8
International Classification: D2401;