Plane parallel optical collimating device employing a cholesteric liquid crystal
First Claim
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1. An optical collimating apparatus for focussing an image at infinity or at a desired finite distance as viewed by an observer, the apparatus comprising:
- a first optical singlet having a first surface and a second surface;
a second optical singlet having a first surface and a second surface, said first surface of said first optical singlet coupled to said first surface of said second optical singlet;
a partially reflective coating interposed between said first surface of said first optical singlet and said first surface of said second optical singlet;
an image source for producing said image with light within at least a first wavelength band and with at least a first rotary sense of circular polarization, said image source proximate to said second surface of said first optical singlet; and
a first cholesteric liquid crystal element proximate to said second surface of said second optical singlet, said first cholesteric liquid crystal element reflecting light of said first rotary sense of circular polarization within said first wavelength band.
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Abstract
A compact lightweight display system which can be used as a collimating eyepiece is provided. The system utilizes a cholesteric liquid crystal device in combination with an optical doublet. A partially reflective coating is at the interface between the two singlets which comprise the doublet. The design of this system reduces the number of element to air and/or element to element interfaces, thus reducing losses and ghosting while making a sturdier, more vibration tolerant display system.
108 Citations
21 Claims
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1. An optical collimating apparatus for focussing an image at infinity or at a desired finite distance as viewed by an observer, the apparatus comprising:
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a first optical singlet having a first surface and a second surface; a second optical singlet having a first surface and a second surface, said first surface of said first optical singlet coupled to said first surface of said second optical singlet; a partially reflective coating interposed between said first surface of said first optical singlet and said first surface of said second optical singlet; an image source for producing said image with light within at least a first wavelength band and with at least a first rotary sense of circular polarization, said image source proximate to said second surface of said first optical singlet; and a first cholesteric liquid crystal element proximate to said second surface of said second optical singlet, said first cholesteric liquid crystal element reflecting light of said first rotary sense of circular polarization within said first wavelength band. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An optical apparatus for combining a first image and a second image, the apparatus comprising:
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a first optical singlet having a first surface and a second surface; a second optical singlet having a first surface and a second surface, said first surface of said first optical singlet coupled to said first surface of said second optical singlet; a partially reflective coating interposed between said first surface of said first optical singlet and said first surface of said second optical singlet; a LCD image source producing said first image with linearly polarized light of a first linear polarization within at least a first wavelength band; a polarizing beam splitter interposed between said LCD image source and said second surface of said first optical singlet, wherein a portion of said light of said first linear polarization and within said first wavelength band from said LCD image source is reflected by said polarizing beam splitter toward said first optical singlet; a second image source producing said second image, wherein a portion of said light from said second image source is transmitted by said polarizing beam splitter toward said first optical singlet; a circular polarizer proximate to said second surface of said first optical singlet, wherein said circular polarizer converts light of said first linear polarization to light of said first rotary sense of circular polarization; and a cholesteric liquid crystal element proximate to said second surface of said second optical singlet, said cholesteric liquid crystal element reflecting light of said first rotary sense of circular polarization within said first wavelength band. - View Dependent Claims (18)
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19. A method for optically collimating an image at infinity or at a desired finite distance from an observer, comprising the steps of:
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directing an image light having components within at least a first predetermined wavelength band and of at least a first rotary sense of circular polarization onto a first surface of an optical doublet, a portion of said image light passing through said optical doublet, wherein said optical doublet is comprised of a first optical singlet and a second optical singlet and a partially reflective coating interposed therebetween; reflecting said passed image light within said first predetermined wavelength band and of said first rotary sense of circular polarization with a cholesteric liquid crystal element, said reflected image light passing through said second surface of said optical doublet; collimating a portion of said reflected image light with said partially reflective coating, said first rotary sense of circular polarization changing to a second rotary sense of circular polarization upon reflection by said partially reflective coating; and projecting said collimated image light of said second rotary sense of circular polarization through said cholesteric liquid crystal element to said observer. - View Dependent Claims (20, 21)
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Specification