Color imager utilizing novel trichromatic beamsplitter and photosensor

• US 4,709,144 A
• Filed: 04/02/1986
• Issued: 11/24/1987
• Est. Priority Date: 04/02/1986
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Vincent, Kent D.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Oen, William L.
• Application Number:
  US06/847,382
• Time in Patent Office: 601 Days
• Field of Search: 250/226, 250/578, 358/49, 350/166, 350/169, 350/170, 350/171, 350/173
• US Class Current: 250/226
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G02B 27/1013 for colour or multispectral image sensors, e.g. splitting an image into monochromatic image components on respective sensors spectral imaging systems G01J
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/148 including stacked surfaces having at least one double-pass partially reflecting surface
• CPC Class Codes: H04N 1/488 using beam-splitters

Abstract

The trichromatic beamsplitter consists of composited dichroic beamsplitter plates that separate a projected image into its three color components with spacial as well as spectral precision. The three linear array photosensor comprises a monolithic sensor having three parallel photodiode arrays spaced precisely to accept the color component images of the trichromatic beamsplitter.

Claims

1. An apparatus for separating electromagnetic waves having wavelengths comprising:

a first transparent layer;

a first filter contiguous with the first side of said first transparent layer for reflecting said electromagnetic waves having said wavelengths within a first range;

a second filter contiguous with the second side of said first first transparent layer for reflecting said electromagnetic waves having said wavelengths within a second range;

a second transparent layer attached to said second filter; and

a third filter contiguous with said second transparent layer for reflecting said electromagnetic waves having said wavelengths within a third range.

4. An apparatus as in claim 1 further comprising:

a transparent extension means attached to said first filter having a first surface oriented normal to the optical axes of said incident electromagnetic waves and a second surface oriented normal to the optical axes of the reflected electromagnetic waves.

5. An apparatus as in claim 4 wherein:

said transparent extension means is a prism.

6. An apparatus as in claim 5 wherein:

said filters reflect said electromagnetic waves having said wavelength within said ranges when said electromagnetic wave is incident upon said filters at 45 degrees; and

said filters and said transparent layers are attached to the hypotenuse side of said prism.

7. An apparatus as in claim 1 further comprising:

a third transparent layer;

a fourth filter contiguous with the first side of said third transparent layer for reflecting said electromagnetic waves having said wavelengths within said third range;

a fifth filter contiguous with the second side of said third transparent layer for reflecting said electromagnetic waves having wavelengths within said second range;

a fourth transparent layer attached to said fifth filter;

a sixth filter contiguous with said fourth layer for reflecting said electromagnetic waves having said wavelengths within said first range; and

wherein said fourth, fifth, and sixth filters are located to receive said electromagnetic waves reflected from said third, second and first filters respectively.

8. An apparatus as in claim 7 wherein:

said fourth, fifth, and sixth filters are located so that said electromagnetic waves having wavelengths within said first, second and third ranges travel the same optical path lengths through said transparent layers.

9. An apparatus as in claim 8 further comprising:

a transparent extension means attached to said first and fourth filters having a surface oriented normal to the optical axes of the incident and exiting electromagnetic waves.

10. An apparatus as in claim 9 wherein:

said transparent extension means is a prism.

11. An apparatus as in claim 10 wherein:

said filters reflect said electromagnetic waves having said wavelength within said ranges when said electromagnetic waves are incident upon said filters at 45 degrees; and

said first filter and said fourth filters are attached to the first and second base sides of said prism.

13. An apparatus as in claim 1 wherein said filters reflect said electromagnetic waves in a direction other than 180 degrees from the optical axes of said electromagnetic waves striking said filters.

18. An apparatus as in claim 1 further comprising:

a first photosensor means aligned to receive said electromagnetic waves reflected from said first filter; and

a second photosensor means aligned to receive said electromagnetic waves reflected from said second filter; and

a third photosensor means aligned to receive said electromagnetic waves reflected from said third filter.

19. An apparatus as in claim 7 further comprising:

a first photosensor means aligned to receive said electromagnetic waves reflected from said fourth filter;

a second photosensor means aligned to receive said electromagnetic waves reflected from said fifth filter; and

a third photosensor means aligned to receive said electromagnetic waves reflected from said sixth filter.

22. An apparatus as in claim 18 further comprising:

a lens to focus said electromagnetic waves onto said filters; and

an illumination source spectrally tailored to the output device.

23. An apparatus as in claim 19 further comprising:

a lens to focus said electromagnetic waves onto said filters; and

an illumination source spectrally tailored to the output device.

25. An apparatus as in claim 19 wherein:

said filters and said photosensor means are packaged together.

26. An apparatus as in claim 1 wherein said transparent layer is glass.

27. An apparatus as in claim 1 wherein said transparent layer is plastic.

28. An apparatus as in claim 1 further comprising:

a means for equalizing the optical path lengths of said electromagnetic waves.

29. An apparatus as in claim 28 further comprising:

a means for detecting said reflected electromagnetic waves.

33. An apparatus as in claim 8 wherein said filters reflect said electromagnetic waves that have said wavelengths within said ranges and that strike said filters at a predetermined angle.

34. An apparatus as in claim 19 wherein said photosensor means are photosensor arrays.

37. An apparatus as in claim 18 wherein said photosensor means are photosensor arrays.

38. An apparatus as in claim 37 wherein said photosensor arrays are located on the same integrated circuit.

2. An apparatus for separating electromagnetic waves having wavelengths comprising:

a first transparent layer;

a first filter contiguous with the first side of said first transparent layer for reflecting said electromagnetic waves having said wavelength within a first range;

a second filter contiguous with the second side of said first transparent layer for reflecting said electromagnetic waves having said wavelengths within a second range; and

a transparent extension means attached to said first filter having a first surface oriented normal to the optical axes of said incident electromagnetic waves and a second surface oriented normal to the optical axes of the reflected electromagnetic waves.

3. An apparatus as in claim 2 wherein:

said transparent extension means is a prism.

12. An apparatus as in claim 2 wherein said filters reflect said electromagnetic waves in a direction other than 180 degrees from the optical axes of said electromagnetic wave striking said filters.

17. An apparatus as in claim 2 further comprising:

a first photosensor means aligned to receive said electromagnetic waves reflected from said first filter; and

a second photosensor means aligned to receive said electromagnetic waves reflected from said second filter.

21. An apparatus as in claim 17 further comprising:

a lens to focus said electromagnetic waves onto said filters; and

an illumination source spectrally tailored to the output device.

24. An apparatus as in claim 17 wherein:

said filters and said photosensor means are packaged together.

30. An apparatus as in claim 32 wherein said filters are precisely located from each other in order to facilitate the creation of equal optical path lengths and to facilitate the alignment of said means for detecting said separated electromagnetic waves.

31. An apparatus as in claim 2 further comprising:

a means for detecting said reflected electromagnetic waves.

32. An apparatus as in claim 2 wherein said filters reflect said electromagnetic waves that have said wavelengths within said ranges and that strike said filters at a predetermined angle.

35. An apparatus as in claim 3 wherein said filters reflect said electromagnetic waves that have said wavelengths within said ranges and that strike said filters at a predetermined angle.

14. An apparatus for separating electromagnetic waves according to wavelength comprising:

a multiplicity of transparent layers;

a multiplicity of filters located on said transparent layers wherein said coatings reflect different ranges of electromagnetic wavelengths; and

wherein said transparent layers with said filters are mounted together.

20. An apparatus as in claim 14 further comprising:

a multiplicity of photosensor means aligned to receive electromagnetic waves reflected from said multiplicity of filters.

15. A method of manufacturing apparatus for separating electromagnetic waves comprising the steps of:

forming a thick glass substrate;

applying a first filter to said substrate;

attaching a thin glass layer to said filter;

grinding said glass layer;

polishing said glass layer; and

applying a second filter to said substrate.

16. A method of manufacturing as in claim 15 wherein the steps of applying, attaching, grinding and polishing are repeated to form additional coatings and layers.

39. An apparatus for separating electromagnetic waves according to wavelength comprising:

a first transparent layer;

a first filter contiguous with the first side of said first transparent layer for reflecting said electromagnetic waves having said wavelength within a first range;

a second filter contiguous with the second side of said first transparent layer for reflecting said electromagnetic waves having said wavelength within a second range; and

a means for equalizing the optical path lengths of said electromagnetic waves.

36. An apparatus as in claim 39 wherein said photosensor arrays are located on the same integrated circuit.

40. An apparatus as in claim 39 further comprising:

a means for detecting said electromagnetic waves that have been reflected by said filters.

41. An apparatus as in claim 40 wherein said means for detecting are photosensors.

42. An apparatus as in claim 41 wherein said photosensors are located on an integrated circuit.

43. An apparatus as in claim 39 wherein said filters reflect said electromagnetic waves that have said wavelengths within said ranges and that strike said filters at a predetermined angle.

44. An apparatus as in claim 43 wherein said transparent layer is glass.

45. An apparatus as in claim 43 wherein said transparent layer is plastic.