Grazing incidence holograms and system and method for producing the same

• US 6,151,142 A
• Filed: 01/16/1998
• Issued: 11/21/2000
• Est. Priority Date: 01/29/1993
• Status: Expired due to Fees

• Current Assignee: Stanley H. Kremen
• Original Assignee: Imedge Technology Incorporated
• Inventors: Metz, Michael H., Coleman, Zane, Phillips, Nicholas J.
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US09/008,348
• Time in Patent Office: 1,040 Days
• Field of Search: 359/3, 359/1, 359/35, 359/34, 359/32
• US Class Current: 359/3
• CPC Class Codes: G02B 6/0033 Means for improving the coupling-out of light from the light guide
• CPC Class Codes: G03H 1/0408 Total internal reflection [TIR] holograms, e.g. edge lit or substrate mode holograms
• CPC Class Codes: G03H 2001/0413 for recording transmission holograms
• CPC Class Codes: G03H 2001/0415 for recording reflection holograms
• CPC Class Codes: G03H 2001/0473 Particular illumination angle between object or reference beams and hologram
• CPC Class Codes: G03H 2001/048 Parallel printer, i.e. a fringe pattern is reproduced
• CPC Class Codes: G03H 2001/207 with modification of the nature of the hologram, e.g. changing from volume to surface relief or from reflection to transmission
• CPC Class Codes: G03H 2001/2223 Particular relationship between light source, hologram and observer
• CPC Class Codes: G03H 2222/47 Evanescent wave
• CPC Class Codes: G03H 2223/18 Prism

Abstract

A method and system are disclosed for recording and displaying grazing-incidence (i.e., steep reference beam angle) holograms supported on a substrate having thin edge-illuminatable geometry. The system and process use thin edge-illuminated substrates that facilitate optimal coupling of the reference light beam at steep angles approaching grazing incidence, while maximizing the contrast of the slanted fringe structures thereof. Different recording techniques are employed when the index of refraction of the substrate is greater than that of the recording medium, than when the index of refraction of the substrate is less than that of the recording medium. A recording and playback system of complementary design is provided for recording slanted-fringe volume holograms under relaxed conditions, without compromising the light diffraction efficiency of the holograms under different playback conditions.

Claims

1. A system for illuminating a volume hologram having slanted fringes, the system comprising:

a substrate made from an optically transparent material having an index of refraction n_s, the substrate having a front and a rear surface disposed substantially parallel to one another, and an edge surface disposed between the front and rear surfaces;

a volume slanted fringe hologram made from an optically transparent material having a bulk index of refraction n_m greater than n_s with the difference in index of refraction therebetween being equal to Δ

n, and a rear surface of the hologram being proximate to the front surface of said substrate along an interface;

a light source for producing an illumination beam which propagates along a single-pass optical path extending through said substrate at a grazing angle of incidence φ

_s, of at least about 80 degrees with respect to the normal to the interface, so that the illumination beam couples into the hologram and interacts with the slanted fringes to produce an output beam;

and wherein the slanted fringe hologram is illuminated in the reflection hologram mode.