Holographic imaging
First Claim
1. An apparatus for imaging an object obscured by a diffusing medium, comprising:
- a pulsed laser light source to generate an object beam (3'"'"') and a reference beam (4'"'"') whereby the object (7) obscured by the diffusing medium can be illuminated with the object beam (3'"'"');
a real time interferogram recording medium (8), comprising a photorefractive medium, arranged to be exposed to, and to record an interferogram formed by the coincidence of light from the object (7) and the reference beam (4'"'"');
a means for reconstructing an image from the interferogram; and
a means for recording the image;
said apparatus including a reference beam path means for guiding the reference beam so that a pulse of the reference beam arrives at the real time interferogram recording medium so as to be coincident with at least one of unscattered light and least scattered light from the object, thereby causing the interferogram recorded to represent the information content contained within the unscattered light or the least scattered light from the object (7).
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Accused Products
Abstract
A holographic imaging apparatus having a pulsed laser light source for generating an object beam and a reference beam whereby an object, obscured by a diffusing medium, is illuminated by the object beam. A real time interferogram recording medium is exposed to the coincidence of light reflected from the object and the reference beam to record an interferogram. A holographic image is then reconstructed from the interferogram and may be viewed and recorded. The pulsed laser light source generates a beam which is divided by a conventional beam splitter device into an object beam and a reference beam. The object beam is then diverged by a lens which forms a diverging object beam to illuminate the object. The reference beam is diverged through another lens to form a diverging reference beam which is directed so that it illuminates a photoreactive crystal. The coincidence of the reflected light and diverging reference beam generates a pattern of interference fringes known as an interferogram which is recorded by the crystal. The apparatus can use time-gating in the holographic medium to use ballistic and snake-like light, which arrives before scattered light, to construct a holographic image. The apparatus can also obtain depth information for 3-D images by using the time-gating technique to obtain the image bearing light from a 3-D object. The apparatus also may record light-in-flight images of the object, to record different depths of the object separately, by using an optical delay assembly.
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Citations
34 Claims
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1. An apparatus for imaging an object obscured by a diffusing medium, comprising:
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a pulsed laser light source to generate an object beam (3'"'"') and a reference beam (4'"'"') whereby the object (7) obscured by the diffusing medium can be illuminated with the object beam (3'"'"'); a real time interferogram recording medium (8), comprising a photorefractive medium, arranged to be exposed to, and to record an interferogram formed by the coincidence of light from the object (7) and the reference beam (4'"'"'); a means for reconstructing an image from the interferogram; and a means for recording the image; said apparatus including a reference beam path means for guiding the reference beam so that a pulse of the reference beam arrives at the real time interferogram recording medium so as to be coincident with at least one of unscattered light and least scattered light from the object, thereby causing the interferogram recorded to represent the information content contained within the unscattered light or the least scattered light from the object (7). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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11. An apparatus for imaging an object obscured by a diffusing medium, comprising:
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a pulsed laser light source to generate an object beam (3'"'"') and a reference beam (4'"'"') whereby the object (7) obscured by the diffusing medium can be illuminated with the object beam (3'"'"'); a real time interferogram recording medium (8), comprising a photorefractive medium, arranged to be exposed to, and to record an interferogram formed by the coincidence of light from the object (7) and the reference beam (4'"'"'); a means for reconstructing an image from the interferogram; and a means for recording the image; wherein said apparatus includes a reference beam path means for guiding the reference beam so that a pulse of the reference beam arrives at the real time interferogram recording medium so as to be coincident with at lease one of unscattered light and least scattered light from the object, thereby causing the interferogram recorded to represent the information content contained within the unscattered light or the least scattered light from the object (7); and wherein the object and reference beams (3, 3'"'"'), (4, 4'"'"') impinge upon the recording medium (8) substantially parallel to each other and the reference beam (4, 4'"'"') passes through an adjustable delay line assembly (14) whereby the length of the path followed by the reference beam (4, 4'"'"') can be adjusted.
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34. A method of imaging an object obscured by a diffusing medium, the method comprising:
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employing a pulsed laser light source to generate an object beam (3'"'"') and a reference beam (4'"'"') whereby the object (7) obscured by the diffusing medium can be illuminated with the object beam (3'"'"'); recording on a real time interferogram recording medium (8) comprising a photorefractive medium, an interferogram formed by the coincidence of light from the object (7) and the reference beam (4'"'"'); guiding the reference beam so that a pulse of the reference beam arrives at the real time interferogram recording medium so as to be coincident with at least one of unscattered light and least scattered light from the object, thereby causing the interferogram recorded to represent the information content contained within the unscattered light or the least scattered light from the object (7); reconstructing an image from the interferogram; and recording the image.
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Specification