US3905684A
Expired / Lapsed
US
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Optical beam splitting system
Assignee: Rank Organization Ltd
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Filing: 1973-09-19
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Granted: 1975-09-16
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Expires: 1993-09-19
Abstract
Abstract A selective beam splitting arrangement having a plurality of reflective and/or transmissive surfaces for separating incident image-forming light into a number of components to provide more than one image also includes a plurality of additional light sources to provide bias illumination of the image planes. The light from the sources is directed to the image planes by at least some of the same surfaces of the beam splitting arrangement which separate the incident light, at least one of the surfaces being geometrically or spectrally incapable of illuminating all the image planes. The optical axis of the light from each source meets a surface of the beam splitting arrangement in a direction which is substantially a mirror image of the optical axis of the incident light.
Inventors
- 👤 Gordon Henry Cook
- 👤 John Anthony Fawcett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:17
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/10; G02B27/1006; G02B27/1013; G02B27/14; G02B27/145
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
335 words
In a color-separating prism assembly having a plurality of prisms comprising a first prism for receiving an image-forming beam of incident light, a second prism, a first dichroic layer contained between the first and second prisms for reflecting one color component of the image-forming light beam, a third prism, and a second dichroic layer contained between the second and third prisms for reflecting a color component of that part of the image-forming light beam transmitted through the first dichroic layer, at least one further color component of the image-forming light beam being transmitted through the second dichroic layer, the prisms being arranged to provide at least three separated image-forming exit beams corresponding to the respective color components, and said assembly comprising means for providing bias illumination along the axes of at least all but one of the exit beams; the improvement according to which the means for providing bias illumination comprises a plurality of bias light sources, a first plane bias light entry surface formed on the third prism of the prism assembly, through which bias light from a first bias light source enters the prism assembly along an optical axis normal to said first plane surface, said optical axis intersecting the second dichroic layer at an angle which is equal and opposite to the angle between said dichroic layer and the axis of the image-forming light beam, a second plane bias light entry surface formed on one of the first and second prisms of the prism assembly, through which bias light from a second bias light source enters the prism assembly along an optical axis normal to said second plane surface, the bias light from said second bias light source being incident on the first dichroic layer, and means restricting the bias light from the first bias light source to emerge from the prism assembly along less than all the axes of the respective color component exit beams, whereby the levels of bias illumination along the respective exit beam axes can be relatively adjusted.
Claim 2
Dependent Claim
335 words
In a color-separating prism assembly having a plurality of prisms comprising a first prism for receiving an image-forming beam of incident light, a second prism, a first dichroic layer contained between the first and second prisms for reflecting one color component of the image-forming light beam, a third prism, and a second dichroic layer contained between the second and third prisms for reflecting a color component of that part of the image-forming light beam transmitted through the first dichroic layer, at least one further color component of the image-forming light beam being transmitted through the second dichroic layer, the prisms being arranged to provide at least three separated image-forming exit beams corresponding to the respective color components, and said assembly comprising means for providing bias illumination along the axes of at least all but one of the exit beams; the improvement according to which the means for providing bias illumination comprises a plurality of bias light sources, a first plane bias light entry surface formed on the third prism of the prism assembly, through which bias light from a first bias light source enters the prism assembly along an optical axis normal to said first plane surface, said optical axis intersecting the second dichroic layer at an angle which is equal and opposite to the angle between said dichroic layer and the axis of the image-forming light beam, a second plane bias light entry surface formed on one of the first and second prisms of the prism assembly, through which bias light from a second bias light source enters the prism assembly along an optical axis normal to said second plane surface, the bias light from said second bias light source being incident on the first dichroic layer, and means restricting the bias light from the first bias light source to emerge from the prism assembly along less than all the axes of the respective color component exit beams, whereby the levels of bias illumination along the respective exit beam axes can be relatively adjusted.
Claim 3
Dependent Claim
42 words
A color-separating prism assembly according to claim 1, including color filtering means whereby the bias light from the second bias light source is caused to emerge from the prism assembly along less than all the axes of the respective color-component exit beams.
Claim 4
Dependent Claim
42 words
A color-separating prism assembly according to claim 1, including color filtering means whereby the bias light from at least one of the first and second bias light sources is caused to emerge along only one of the color component exit beam axes.
Claim 5
Dependent Claim
39 words
A color-separating prism assembly according to claim 1, wherein the bias light from the second bias source is incident in succession on the first and second dichroic layers to be partially reflected and partially transmitted by each said layer.
Claim 6
Dependent Claim
83 words
A color-separating prism assembly according to Claim 1, wherein the second plane bias light entry face is provided on the second prism, and the bias light from the second bias light source is incident on the first dichroic layer along the said optical axis normal to the second plane bias light entry face, said optical axis making an angle with the first dichroic layer equal and opposite to the angle between said first dichroic layer and the axis of the image-forming light beam.
Claim 7
Dependent Claim
73 words
A color-separating prism assembly according to claim 1, wherein the second plane bias light entry face is provided on the first prism, and the bias light from the second bias light source is reflected at that face of the first prism through which the image-forming light beam enters said first prism, the reflected bias light being directed along the axis of the image-forming light beam to be incident on the first dichroic layer.
Claim 8
Dependent Claim
24 words
A color-separating prism assembly according to claim 1, including an entry prism for the image-forming light beam located in front of the first prism.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |