Robert F Lavallee

US Patent:

39470997, Mar 30, 1976

Filed:

Jan 2, 1975

Appl. No.:

5/538229

Inventors:

Bernard Grolman - Worcester MA
Robert G. Lavallee - Ashland MA

Assignee:

American Optical Corporation - Southbridge MA

International Classification:

A61B 306
G02B 516

US Classification:

351 35

Abstract:

Apparatus for evaluation a human subject's color vision response including light emmiting diodes providing luminance in the yellow and red and green color spectrums, means for controlling the individual luminescence of the red and green diodes in an inverse relationship and means for displaying the yellow and red-green luminescence for comparative viewing by the human subject.

US Patent:

39784142, Aug 31, 1976

Filed:

Mar 25, 1975

Appl. No.:

5/561748

Inventors:

Robert E. Bober - Framingham MA
Robert G. Lavallee - Ashland MA

Assignee:

American Optical Corporation - Southbridge MA

International Classification:

H03K 304

US Classification:

328132

Abstract:

An electrical circuit for operating upon a slowly varying input signal (on the order of one volt per minute) to provide an output signal representative of the input signal derivative. The circuitry employs at least two feedback loops, one of which is constructed similar to an integrator amplifier. One particularly useful electro-medical application of this apparatus and method lies in the measurement of osmotic fragility of red blood cells, where percentage hemolysis of the blood slowly varies as a function of tonicity of suspension of the medium in which the blood sample is suspended. In this measurement the exact point of maximum slope is important and is provided by the present invention.