PYROELECTRIC DETECTOR

• US 3,816,750 A
• Filed: 01/11/1973
• Issued: 06/11/1974
• Est. Priority Date: 06/04/1971
• Status: Expired due to Term

• Current Assignee: Sie T. Liu
• Original Assignee: Sie T. Liu
• Inventors: Liu, Sie T.
• Primary Examiner(s): Borchelt, Archie R.
• Assistant Examiner(s): Willis, Davis L.
• Application Number:
  US05/322,816
• Time in Patent Office: 516 Days
• Field of Search: 252/520 250/338 73/355R
• US Class Current: 250/338.3
• CPC Class Codes: G01J 5/34 using capacitors, e.g. pyroelectric capacitors
• CPC Class Codes: G01K 7/003 using pyroelectric elements radiation pyrometers G01J5/00

Abstract

A pyroelectric detector is formed by a hot-pressed ceramic body of ferroelectric Lead Lanthanum Zirconate Titanate (PLZT) having the formula Pb1 xLax(ZryTiz)1 x/4O3.

Claims

2. The pyroelectric detector of claim 1 wherein the body has a dielectric constant epsilon of greater than about 1,000.

3. The pyroelectric detector of claim 2 wherein x is greater than about 0.04.

4. The pyroelectric detector of claim 3 wherein the y to z ratio is between about 60 to 40 and about 80 to 20.

5. The pyroelectric detector of claim 2 wherein the body has a dielectric constant epsilon of greater than about 3,000.

6. The pyroelectric detector of claim 5 wherein x is greater than about 0.06.

7. The pyroelectric detector of claim 6 wherein the y to z ratio is between about 60 to 40 and about 70 to 30.

8. The pyroelectric detector of claim 5 wherein the body has a dielectric constant of greater than about 3,600.

9. The pyroelectric detector of claim 8 wherein the y to z ratio is between about 62 to 38 and about 70 to 30.

10. The pyroelectric detector of claim 9 wherein x is greater than about 0.07.

11. The pyroelectric detector of claim 1 and further comprising chopper means for modulating radiation incident the body.

12. The pyroelectric detector of claim 1 wherein the body does not exhibit self-depoling and is thermal noise limited.

13. The pyroelectric detector of claim 1 wherein the body has a thickness of between 3 mils and 5 mils.

14. The pyroelectric detector of claim 1 wherein the electrode means are silver layers on opposite surfaces of the body.

15. The pyroelectric detector of claim 1 wherein epsilon , the absorption coefficient of an electrode exposed to radiation, is approximately unity.

16. A small element pyroelectric detector array comprising:

a body of ferroelectric Pb1 xLax(ZryTiz)1 x/4O3, wherein x is greater than about 0.015 and y + z 1, the body having a dielectric constant epsilon greater than about 1,000, a plurality of electrically poled regions of the body, electrode means attached to each of the plurality of electrically poled regions, and amplification means connected to the electrode means to amplify the pyroelectric signal from each of the plurality of electrically poled regions.

17. The pyroelectric detector array of claim 16 wherein x is greater than about 0.04.

18. The pyroelectric detector array of claim 17 wherein the body is essentially in the rhombohedral phase.

19. The pyroelectric detector array of claim 18 wherein the y to z ratio is between about 60 to 40 and about 80 to 20.

20. The pyroelectric detector array of claim 16 wherein each of the plurality of electrically poled regions has an area of less than about 2,000 by 2,000 microns.

21. The pyroelectric detector array of claim 20 wherein each of the plurality of electrically poled regions has an area greater than about 25 by 25 microns.

22. The pyroelectric detector array of claim 21 wherein each of the plurality of electrically poled regions has an area of about 100 by 100 microns.

23. The pyroelectric detector array of claim 14 wherein the dielectric constant epsilon is greater than about 3,000.

24. The pyroelectric detector array of claim 23 wherein x is greater than about 0.06.

25. The pyroelectric detector array of claim 24 wherein the body is essentially in the rhombohedral phase.

26. The pyroelectric detector array of claim 25 wherein the y to z ratio is between about 60 to 40 and about 70 to 30.

27. The pyroelectric detector array of claim 23 wherein each of the plurality of electrically poled regions has an area of less than about 1,500 by 1,500 microns.

28. The pyroelectric detector array of claim 27 wherein each of the plurality of electrically poled regions has an area greater than about 25 by 25 microns.

29. The pyroelectric detector array of claim 28 wherein each of the plurality of electrically poled regions has an area of about 100 by 100 microns.

30. The pyroelectric detector array of claim 23 wherein the dielectric constant epsilon is greater than about 3,600.

31. The pyroelectric detector array of claim 30 wherein x is greater than about 0.07.

32. The pyroelectric detector array of claim 31 whErein the body is essentially in the rhombohedral phase.

33. The pyroelectric detector array of claim 32 wherein the y to z ratio is between about 62 to 38 and about 70 to 30.

34. A pyroelectric detector having stable pyroelectric detector properties over a large range of operating temperatures, the pyroelectric detector comprising:

an electrically poled body of tetragonal ferroelectric Pb1 xLax(ZryTiz)1 x/4O3, wherein x is greater than about 0.015 and y + z 1, electrodes attached to the body, and amplification means connected to the electrodes to amplify the pyroelectric signal from the body.

35. The pyroelectric detector of claim 34 wherein the body has a dielectric constant epsilon of greater than about 1,000.

36. The pyroelectric detector of claim 34 wherein x is greater than about 0.04.

37. The pyroelectric detector of claim 35 wherein the dielectric constant epsilon is greater than about 3,000.

38. The pyroelectric detector of claim 37 wherein x is greater than about 0.06.

39. A method of detecting thermal radiation comprising:

subjecting an electrically poled body of ferroelectric Pb1 xLax(ZryTiz)1 x/4O3, wherein x is greater than about 0.015 and y + z 1, to a change in temperature, and sensing the voltage produced across the body as a result of the temperature change.

40. The method of claim 39 wherein the body has a dielectric constant epsilon of greater than about 1,000.

41. The method of claim 40 wherein x is greater than about 0.04.

42. The method of claim 41 wherein the body is essentially in the rhombohedral phase.

43. The method of claim 42 wherein the ratio of y to z is between about 60 to 40 and about 80 to 20.

44. The method of claim 41 wherein the body is essentially in the tetragonal phase.

45. The method of claim 40 wherein the dielectric constant epsilon is greater than about 3,000.

46. The method of claim 45 wherein x is greater than about 0.06.

47. The method of claim 46 wherein the body is essentially in the rhombohedral phase.

48. The method of claim 47 wherein the ratio of y to z is between about 60 to 40 and about 70 to 30.

49. The method of claim 46 wherein the body is essentially in the tetragonal phase.

50. The method of claim 45 wherein the dielectric constant epsilon is greater than about 3,600.

51. The method of claim 50 wherein x is greater than 0.07.

52. The method of claim 51 wherein the body is essentially in the rhombohedral phase.

53. The method of claim 52 wherein the ratio of y to z is between about 62 to 38 and about 70 to 30.