Infrared thermometer with automatic calibration

[54] INFRARED THERMOMETER WITH AUTOMATIC CALIBRATION

[75] Inventors: Herbert L. Berman, Los Altos Hills;

Richard W. Singer, Palo Alto, both of
Calif.

[73] Assignee: Optical Sensors, Inc., Los Altos,
Calif.

[21] Appl. No.: 817,930

[22] Filed: Jan. 13,1986

[51] IntCl.4 G01J5/10

[52] U.S. CI 128/664; 128/736;

374/129; 374/158

[58] Field of Search 128/664, 736; 374/129,

374/126, 158

[56] References Cited

U.S. PATENT DOCUMENTS

3,449,121 6/1969 Astheimer 73/355 R

3,581,570 6/1971 Wertz 73/355 R

3,673,868 7/1972 Beury, III et al 73/343 R

3,878,836 4/1975 Twentier 128/9

3,949,746 4/1976 Twentier 128/9

4,005,605 2/1977 Michael 374/129

4,343,185 8/1982 Knute 374/158

4,372,690 2/1983 Berman et al 374/29

4,497,585 2/1985 Paull et al 128/736

Infrared radiation emitted from tissue surface of body cavity is measured by an infrared sensor located within a probe which generates a signal voltage dependent on the difference in temperature between the tissue and the infrared sensor. An additional ambient sensor measures the ambient temperature of the infrared sensor. The signals of the two sensors are added. To calibrate and eliminate errors, the housing of the device is provided with a chamber shaped to receive the probe and containing a target viewed by the infrared sensor. An error signal is thus generated which is added to the signals of the two sensors when they view the body tissue. A disposable, sanitary cover for the probe is made of a truncated polyethylene member of substantially uniform thickness closed by an end window. A filter in the probe suppresses absorption bands of polyethylene to eliminate errors due to minor variations in cover thick

13 Claims, 3 Drawing Sheets