Dosimeter reading apparatus with optical laser converter

• US 5,081,363 A
• Filed: 04/26/1991
• Issued: 01/14/1992
• Est. Priority Date: 09/20/1984
• Status: Expired due to Fees

• Current Assignee: Harris Trust and Savings Bank
• Original Assignee: International Sensor Technology, Inc. (Keithley Instruments, Inc.)
• Inventors: Hoelscher, James W., Bloomsburg, Carl D., Tetzlaff, Wolfgang, Braunlich, Peter F.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Glick, Edward J.
• Application Number:
  US07/692,171
• Time in Patent Office: 263 Days
• Field of Search: 250/484.1 R, 250/484.1 A, 250/484.1 B, 250/484.1 C, 250/337, 250/461.1, 250/354.1, 250/458.1, 250/459.1, 250/328
• US Class Current: 250/484.5
• CPC Class Codes: G01T 1/11 Thermo-luminescent dosimeters thermo-luminescent compositions C09K11/00
• CPC Class Codes: G01T 1/115 Read-out devices

Abstract

Disclosed is a laser dosimeter reading apparatus having a controllable optical laser converter for providing multiple stimulating laser beams. The converter laser dosimeter reader can be used to stimulate or otherwise treat dosimeter elements to perform two or more distinct processes on a particular dosimeter element. Additionally, the convertible dosimeter reader can be used to read multiple different types of dosimeter elements contained on a single dosimeter badge, thereby allowing a badge to be read in a multi-stage reading operation in a single dosimeter reader which is preferably automated. The optical laser converter includes a converter block assembly which defines multiple optical pathways therethrough. The convert block assembly is movable between different positions to align the different optical pathways with an incoming laser beam. The output laser beams from the different optical pathways of the converter have differing laser beam characteristics suitable for different types of dosimeters or differing treatment processes. The output beams from the optical pathways are preferably passed through an imaging assembly which images the beams onto the dosimeters being stimulated or for other uses as the laser beam converter may be utilized. The disclosure also includes methods for converting a laser beam and for reading radiation dosimeters.

Claims

1. A convertible radiation dosimeter reading apparatus for performing a plurality of differing laser stimulated reading modes of operation;

the laser stimulated reading modes each measuring a state of ionization of at least one type of radiation sensing element which results from exposure of the radiation sensing element to ionizing radiation, comprising;

a laser beam source for providing a laser beam;

a laser beam converter for receiving said laser beam and controllably converting the laser beam into a plurality of output laser beams having differing characteristics to provide differing stimulating laser beams to read radiation dosimeters in a plurality of reading modes;

an emission detector for measuring emission from a dosimeter which has been stimulated by at least one of the stimulating laser beams;

wherein the laser beam converter includes at least one laser beam equalizer for equalizing the laser power density of at least one of the stimulating laser beams.

2. A convertible radiation dosimeter reading apparatus according to claim 1 and wherein the laser beam converter includes a laser beam power reducer for reducing the laser power density of at least one of the stimulating laser beams.

3. A convertible radiation dosimeter reading apparatus according to claim 1 and wherein the laser beam converter includes at least one laser beam focuser for focusing at least one of the stimulating laser beams.

4. A convertible radiation dosimeter reading apparatus according to claim 1 and wherein the laser beam converter includes:

a laser beam power reducer for reducing the laser power density of at least one of the stimulating laser beams;

at least one laser beam focuser for focusing at least one of the stimulating laser beams.

5. A convertible radiation dosimeter reading apparatus according to claim 1 further comprising at least one dosimeter holder for holding at least one dosimeter in position to be stimulated by at least one of the stimulating laser beams.

6. A convertible radiation dosimeter reading apparatus according to claim 1 further comprising at least one dosimeter holder for holding at least two dosimeters in position to be stimulated by at least two of the stimulating laser beams having differing beam characteristics.

7. A convertible radiation dosimeter reading apparatus according to claim 1 further comprising at least one dosimeter holder for holding a dosimeter badge having a plurality of dosimeters thereon at a plurality of positions wherein at least one of the stimulating laser beams stimulates and reads a plurality of the dosimeters on the badge.

8. A convertible radiation dosimeter reading apparatus according to claim 1 further comprising at least one automatically controlled dosimeter holder for automatically holding a dosimeter badge having a plurality of dosimeters thereon at a plurality of positions wherein at least one of the stimulating laser beams automatically stimulates and reads a plurality of the dosimeters on the badge.

9. A convertible radiation dosimeter reading apparatus according to claim 1 further comprising at least one dosimeter holder for holding a dosimeter badge having a plurality of dosimeters thereon;

said dosimeter holder being controllably movable between a plurality of dosimeter badge holding positions;

said plurality of dosimeter badge holding positions providing controlled presentation of a plurality of said dosimeters in at least one dosimeter reading position to thereby allow different dosimeters to be stimulated in differing reading modes using differing stimulating laser beams from the laser beam converter.

10. A convertible radiation dosimeter reading apparatus according to claim 1 wherein the laser beam converter further comprises:

at least one output beam splitter for splitting at least one of the output laser beams into a secondary output beam;

at least one secondary output beam detector for detecting a characteristic of the secondary output beam.

11. A convertible radiation dosimeter reading apparatus according to claim 10 and further comprising at least one laser beam power reducer for reducing the power of at least one of said output laser beams.

12. A convertible radiation dosimeter reading apparatus for performing a plurality of differing laser stimulated reading modes of operation;

the laser stimulated reading modes each measuring a state of ionization of at least one type of radiation sensing element which results from exposure of the radiation sensing element to ionizing radiation, comprising;

a laser beam source for providing a laser beam;

a laser beam converter for receiving said laser beam and controllably converting the laser beam into a plurality of output laser beams having differing characteristics to provide differing stimulating laser beams to read radiation dosimeters in a plurality of reading modes;

an emission detector for measuring emission from a dosimeter which has been stimulated by at least one of the stimulating laser beams;

at least one dosimeter holder for holding a dosimeter badge having a plurality of dosimeters thereon;

said dosimeter holder being controllably movable between a plurality of dosimeter badge holding positions;

said plurality of dosimeter badge holding positions providing controlled presentation of a plurality of said dosimeters in at least one dosimeter reading position to thereby allow different dosimeters to be stimulated in differing reading modes using differing stimulating laser beams from the laser beam converter.

13. A method for reading a dosimeter badge having at least one dosimeter which requires treatment with a plurality of stimulating laser beams having differing beam characteristics:

positioning a dosimeter in at least one reading position;

stimulating the dosimeter with a first stimulating laser beam;

stimulating the dosimeter with a second stimulating laser having beam characteristics different from said first stimulating laser beam;

wherein at least one of said stimulating steps includes stimulating with a laser beam which has been equalized to provide a more uniform laser beam power density.

14. A method according to claim 13 wherein at least one of said stimulating steps includes stimulating with a laser beam which has been focused.

15. A method according to claim 13 wherein at least one of said stimulating steps includes stimulating with a laser beam which has been focused to provide a small stimulating laser beam less than 100 microns in width.

16. A method according to claim 13 further comprising reducing beam power of at least one of said stimulating laser beams.

17. A method according to claim 13 further comprising reducing beam power of at least one of said stimulating laser beams by splitting an incoming laser beam.

18. A method according to claim 13 further comprising detecting emission from at least one of said dosimeters as a result of at least one of said stimulating steps.

19. A method according to claim 13 wherein said laser beam which has been equalized is at least partially equalized by passing a laser beam through an optical channel having reflective walls.

20. A convertible radiation dosimeter reading apparatus for performing a plurality of differing laser stimulated reading modes of operation;

the laser stimulated reading modes each measuring a state of ionization of at least one type of radiation sensing element which results from exposure of the radiation sensing element to ionizing radiation, comprising;

a laser beam source for providing a laser beam;

a laser beam converter for receiving said laser beam and controllably converting the laser beam into a plurality of output laser beams having differing characteristics to provide differing stimulating laser beams to read radiation dosimeters in a plurality of reading modes;

an emission detector for measuring emission from a dosimeter which has been stimulated by at least one of the stimulating laser beams;

wherein the laser beam converter further comprises at least one beam equalizer for equalizing the cross-sectional power density of at least one of the output laser beams;

said beam equalizer including an optically transmissive channel having interior walls which are reflective of the laser beam transmitted therethrough.

21. A convertible radiation dosimeter reading apparatus according to claim 20, said beam equalizer including an optically transmissive channel having interior walls which are reflective of the laser beam transmitted therethrough and a lens for dispersing the laser beam along the interior walls.

22. A convertible radiation dosimeter reading apparatus for performing a plurality of differing laser stimulated reading modes of operation;

the laser stimulated reading modes each measuring a state of ionization of at least one type of radiation sensing element which results from exposure of the radiation sensing element to ionizing radiation, comprising;

a laser beam source for providing a laser beam;

a laser beam converter for receiving said laser beam and controllably converting the laser beam into a plurality of output laser beams having differing characteristics to provide diffusing stimulating laser beams to read radiation dosimeters in a plurality of reading modes;

an emission detector for measuring emission from a dosimeter which has been stimulated by at least one of the stimulating laser beams;

wherein the laser beam converter further comprises at least one laser beam power reducer to reduce the power of at least one of the output laser beams;

said laser beam power reducer including a beam splitter for reflecting a portion of the laser beam to thereby reduce power of the laser beam.

23. A convertible radiation dosimeter reading apparatus according to claim 22 wherein said beam splitter is positioned to split an incoming laser beam.