United States Patent [i9] [ii] Patent Number: 5,030,834
Lindmayer et al. [45] Date of Patent: Jul. 9, 1991
[54] FIBER OPTIC DOSIMETER SYSTEM USING ELECTRON TRAPPING MATERIALS
[75] Inventors: Joseph Lindmayer, Potomac; Charles Y. Wrigley, Ijamsville, both of Md.
[73] Assignee: Quantex Corporation, Rockville, Md.
[21] Appl. No.: 281,217
[22] Filed: Dec. 8, 1988
Related U.S. Application Data
[63] Continuation-in-part of Set. No. 127,118, Dec. 1, 1987, Pat. No. 4,855,603.
[51] Int. CI.' G01T1/10
[52] U.S. CI 250/484.1; 250/368
[58] Field of Search 250/484.1 C, 484.1 B,
250/484.1 A, 494.1 R, 368; 128/653 R
[56] References Cited
U.S. PATENT DOCUMENTS
2,761,070 8/1956 Moos et al 250/484.1 C
3,294,700 12/1966 Bedier et al 250/484.1 C
3,412,248 11/1968 Kastner et al 250/484.1 C
4,333,013 6/1982 Burgkhardt et al 250/484.1 C
4,492,121 1/1985 Lehto 250/227
4,507,562 3/1985 Gasiot et al 250/484.1 C
4,822,520 4/1989 Lindmayer 252/301.4 S
4,855,603 8/1989 Lindmayer 250/484.1 B
FOREIGN PATENT DOCUMENTS
156575 9/1982 Japan 250/227
117477 7/1983 Japan 250/368
OTHER PUBLICATIONS P. Braunlich et al., "A Remote Fibre-Optic Mi
crodosimetry Reader", Radiation Protection Dosimetry, vol. 6, No. 1-4, pp. 103-107, Nuclear Technology Publishing (1984).
Primary Examiner—Carolyn E. Fields
Attorney, Agent, or Firm—Ostrolenk, Faber, Gerb &
Soffen
[57] ABSTRACT
A fiber optic dosimeter in which an electron trapping material is coated onto a tip of an optical fiber. The tip is placed in a region where radiation is to be measured, and the opposite end of the optical fiber, from which radiation readings are measured, is placed in a location remote from the radiation source. When radiation impinges upon the electron trapping material, electrons in the material are raised to a higher state where they are trapped and stay indefinitely. When infrared light strikes the material, the stored electrons are released from their traps and, upon falling to a lower energy level, emit visible light which can be detected and measured. Thus, to measure the amount of ambient radiation, the electron trapping material is stimulated with infrared light from an infrared source at the opposite end of the optical fiber. This infrared stimulation releases trapped electrons and causes the emission of visible light, at least a portion of which is collected and directed back down the optical fiber to the visible light detector, where it is converted into an electrical signal and measured.
