Medium, system and method for optical recording

• US 6,697,315 B1
• Filed: 07/27/2000
• Issued: 02/24/2004
• Est. Priority Date: 07/27/2000
• Status: Expired due to Fees

• Current Assignee: Polytris, Ltd.
• Original Assignee: Polytris, Ltd.
• Inventors: Yelema, Bormashenko, Edward, Bormashenko, Romah, Pogreb, Avigdor, Sheshnev, Katzir, Abraham
• Primary Examiner(s): EDUN, MUHAMMAD N
• Application Number:
  US09/628,111
• Time in Patent Office: 1,307 Days
• Field of Search: 369/100, 369/275.1, 369/275.2, 369/275.3, 369/275.4, 369/283, 369/47.1, 369/53.1, 369/59.1
• US Class Current: 369/100
• CPC Class Codes: B41M 5/267 Marking of plastic artifacts, e.g. with laser
• CPC Class Codes: G11B 7/00455 involving reflectivity, absorption or colour changes
• CPC Class Codes: G11B 7/0052 involving reflectivity, absorption or colour changes
• CPC Class Codes: G11B 7/127 Lasers; Multiple laser arrays lasers per se H01S
• CPC Class Codes: G11B 7/1384 Fibre optics
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/245 containing a polymeric component

Abstract

An optical recording medium, an optical recording system and an optical recording method, based on the suppression of the absorption coefficient of a polymeric film at selective wavelength in the infra-red as a result of irradiation the film with a beam of a CO₂ laser. The magnitude of the effect, which is observable only above a threshold power of the laser beam, is related to the energy deposited by the writing beam. Optical recorded information is stored in the modified absorbance spectrum of the polymer and is read by an infra-red photometric device in the transmission mode.

Claims

1. An optical recording medium comprising:

(a) a first transparent substrate having an optically flat face;

(b) a recording layer which includes a polymeric film overlaid on said optically flat face of first transparent substrate; and

(c) a second transparent substrate in contact with said polymeric film;

wherein said second transparent substrate is at least partially transparent in a wavelength range from about 1 micrometer to about 20 micrometer and has an absorbance of at most about 0.3 at a wavelength range from about 9 micrometer to about 11 micrometer.

2. An optical recording medium as in claim 1 wherein said first transparent substrate is at least partially transparent in the wavelength range from about 1 micrometer to about 20 micrometer.

3. An optical recording medium as in claim 1 wherein said polymeric film has at least one absorbance peak in a spectral region from about 1 micrometer to about 20 micrometer.

4. An optical recording medium as in claim 1 wherein said polymeric film is selected from the group consisting of a thermoplastic polymer and a thermosetting polymer.

5. An optical recording medium as in claim 4 wherein said thermoplastic polymer is selected from the group which consists of polyethylene, polypropylene, polystyrene, polycarbonate and polysulfone.

6. An optical recording medium as in claim 4 wherein said thermosetting polymer is selected from the group consisting of poly-vinyl-ester and an epoxy resin.

7. An optical recording medium as in claim 1 wherein material of said first transparent substrate is selected from the group consisting of silver halide, thallium halide, zinc chalconide and germanium.

8. An optical recording medium as in claim 1 further comprising a mechanism for isolating said polymeric film from oxygen.

9. An optical recording medium as in claim 1 wherein material of said second transparent substrate is selected from the group consisting of silver halide, thallium halide, zinc chalconide and germanium.

10. An optical recording and retrieval system comprising:

(a) an optical recording medium having at least one absorption band in the spectral region from about 2 micrometer to about 20 micrometer;

(b) a first infra-red light source to irradiate on a selected portion of said optical recording medium; and

(c) a mechanism to determine changes in said at least one absorbance band at said irradiated portion of said optical recording medium.

11. A system as in claim 10 wherein said first infra-red light source includes a laser.

12. A system as in claim 11 wherein said laser is a CO₂ laser.

13. A system as in claim 12 wherein said CO₂ laser is a CO₂ tunable laser.

14. A system as in claim 12 wherein power of radiation at said selected portion of said optical recording medium by said CO₂ laser exceeds a threshold value.

15. A system as in claim 14 wherein said threshold value is about 0.5 W.

16. The system as in claim 10 further including:

(d) a mechanism for guiding a light beam from said first infra-red light source toward said optical recording medium.

17. The system of claim 16 wherein said mechanism for guiding said light beam toward said optical recording medium includes an infra-red optical fiber.

18. The system of claim 16 wherein said mechanism for guiding said light beam toward said optical recording medium includes a deflection mirror.

19. The system of claim 10 wherein area of said selected portion of said recording medium is confined to a spot.

20. The system of claim 19 wherein said spot has a diameter of at most about a wavelength of said first infra-red light source.

21. The system of claim 19 further comprising:

(d) a mechanism for changing a location of said spot on said optical recording medium.

22. The system of claim 21 wherein said mechanism for changing location of said spot on said optical recording medium includes a deflection mirror.

23. The system of claim 21 wherein said mechanism for changing location of said spot on said optical recording medium includes an infra-red optical fiber.

24. The system of claim 21 wherein said mechanism for changing location of said spot on said optical recording medium includes a mechanism for moving of said optical recording medium relative to a focal point of a light beam of said first light source.

25. The system as in claim 10 wherein said mechanism of determining said change in said at least one absorption band includes:

(i) a second infra-red light source to provide light which includes a wavelength within said at least one absorption band; and

(ii) a device to measure an intensity of said light at said wavelength.

26. The system as in claim 25 wherein said second infra-red light source includes a tunable infra-red laser.

27. The system as in claim 25 wherein said measuring device is selected from the group consisting of infra-red power meters, infra-red detectors, infra-red spectrophotometers and infra-red imagers.

28. The system of claim 25 wherein said mechanism of determining said change in said at least one absorption band further includes:

(iii) a mechanism for guiding a light beam from said second infra-red light source toward said optical recording medium.

29. The system of claim 28 wherein said mechanism for guiding said light beam toward said optical recording medium includes an infra-red optical fiber.

30. The system of claim 28 wherein said mechanism for guiding said light beam toward said optical recording medium includes a deflection mirror.

31. A method for optical recording and retrieval of a plurality of data points comprising the steps of:

(a) providing a polymeric layer having at least one absorbance peak in the spectral region from about 1 micrometer to about 20 micrometer, for each data point;

(b) producing a light pulse having a power related to a value of said each data point; and

(c) changing said at least one absorbance peak of said polymeric layer by irradiating a respective portion of said polymeric layer with said light pulse.

32. The method of claim 31 wherein said light pulse has a wavelength in the spectral range from about 1 micrometers to about 20 micrometers.

33. The method of claim 32 wherein said light pulse is effective to bleach said respective portion of said polymeric film if said power of said light pulse exceeds a threshold value.

34. The method of claim 33 wherein said threshold value is about 0.5 W.

35. The method of claim 31 wherein said polymeric layer has at least one absorbance peak in a spectral region from about 1 micrometer to about 20 micrometer.

36. The method of claim 31 wherein material of said polymeric layer is selected from the group consisting of a thermoplastic polymer and a thermosetting polymer.

37. The method of claim 36 wherein said thermoplastic polymer is selected from the group which consists of polyethylene, polypropylene, polystyrene, polycarbonate and polysulfone.

38. The method of claim 36 wherein said thermosetting polymer is selected from the group consisting of poly-vinyl-ester and an epoxy resin.

39. The method of claim 31 wherein said respective portion of said polymeric layer is confined to a spot.

40. The method of claim 39 further comprising:

(d) moving said spot on said polymeric layer.

41. The method of claim 39 wherein diameter of said spot is about a wavelength of said light pulse.

42. The method of claim 39 wherein at least two of said spots corresponding to at least two of said data points respectively have a same location on the said polymeric film.

43. The method of claim 31 further comprising the steps of:

(d) determination an amount of said changing of said at least one absorbance peak at said irradiated portion of said polymeric layer.

44. The method of claim 43 wherein said determination includes:

(i) transmitting a second beam of light through said polymeric film and

(ii) measuring an attenuation of said transmitted beam.

45. The method of claim 44 wherein said attenuation measurement is effected with a device selected from the group consisting of infra-red power meters, infra-red detectors, infra-red spectrophotometers and infra-red imagers.

46. The method of claim 44 wherein said first beam of light and said second beam of light have substantially the same wavelength.

47. The method of claim 44 wherein said first beam of light and said second beam of light originate from a common source of light.

48. A method for optical marking and authentication of articles in the IR comprising the steps of:

(a) providing an article which includes a polymeric layer having at least one absorbance peak in the spectral region from about 1 micrometer to about 20 micrometer;

(b) irradiating a portion of said polymeric layer with an IR light beam of a CO₂ laser to bleach said at least one absorbance peak and,

(c) detecting said bleaching of at least one absorbance peak.