Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Patent
1993-04-30
1995-11-28
Lerner, Martin
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
359 18, 359562, G02B 532, G02B 528, G02B 2742
Patent
active
054713269
ABSTRACT:
A holographic optical element (HOE) includes a substrate structure having rotational symmetry with respect to a rotational axis for rotatively supporting at least two holograms. A first hologram on the substrate structure in the path of a normally incident beam diffracts the beam by a first acute angle and in a first radial direction from the rotational axis to a first redirected path. A second hologram on the substrate structure in the first redirected path diffracts the beam by a different second acute angle and in an opposite second radial direction from the rotational axis to a second redirected path. As a result, the two holograms may be used to achieve a second redirected path at an angle to the rotational axis that has a size which is the difference between the size of the first angle and the size of the second angle. The substrate structure may include first, second, and third disc-shaped substrates bonded together so that the third substrate is in between the first and second substrates, and a thin-film interference filter may be included on the third substrate to suppress zero-order leakage through the first hologram. The filter element may include one of a dielectric stack, a transmission hologram, or a reflectance hologram. The first hologram may be imprinted to achieve total internal reflection of zero-order leakage through the second hologram. An additional interference filter may be included on either the output face of the HOE or on a separate window element in order to reflects any zero-order leakage from the second hologram. The HOE may also have Schmidt-type aberration correction superimposed on at least one of the holograms to compensate for spherical aberrations from an all spherical Cassegrain type of telescope.
REFERENCES:
patent: 3334956 (1967-08-01), Staunton
patent: 4895419 (1990-01-01), Doyle et al.
patent: 4948258 (1990-08-01), Caimi
patent: 5046794 (1991-09-01), Ritter et al.
patent: 5119231 (1992-06-01), Nelson et al.
Hall James T.
Levine Seymour
O'Connor Arthur B.
Raffensperger Susan M.
Anderson Terry J.
Hoch Jr. Karl J.
Lerner Martin
Northrop Grumman Corporation
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