Diffraction device

• US 5,363,220 A
• Filed: 01/07/1993
• Issued: 11/08/1994
• Est. Priority Date: 06/03/1988
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kuwayama, Tetsuro, Kushibiki, Nobuo, Taniguchi, Naosato, Yoshinaga, Yoko
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US08/001,405
• Time in Patent Office: 670 Days
• Field of Search: 350/3.6, 350/3.61, 350/3.7, 350/3.72, 350/3.77, 350/174, 340/705, 359/3, 359/13, 359/15, 359/19, 359/34, 359/124, 359/630, 359/633, 359/130, 359/566, 359/569, 359/571, 359/572, 359/576, 385/37, 430/1
• US Class Current: 359/3
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams

Abstract

The present invention provides a diffraction device having a high diffraction efficiency with respect to a wide-band radiation beam. A diffraction device comprises a substrate and a diffraction grating formed on the substrate, wherein the diffraction grating is formed so that a full-width of wavelength at half maximum of a diffraction efficiency of a beam diffracted by the diffraction grating is not less than about 8% of a value of a center wavelength of the diffracted beam.

Claims

1. A head-up display apparatus, comprising:

a displaying device for displaying an image; and

an optical system for directing a beam indicative of said image from said displaying device to a viewer, said optical system including;

a beam combiner; and

a relay member for diffracting said beam and making it incident on said beam combiner, at which the beam is rediffracted and directed to the viewer, wherein a half-width of a wavelength spectrum of a diffraction efficiency of said relay member is set to be equal to or greater than 8% of a central wavelength of the wavelength spectrum, and

wherein a half-width of a wavelength spectrum of a diffraction efficiency of said beam combiner is smaller than that of said relay member.

2. An apparatus according to claim 1, wherein said beam combiner comprises volume-phase type hologram.

3. An apparatus according to claim 2, wherein said volume-phase type hologram causes said beam to be reflectively diffracted.

4. An apparatus according to claim 3, wherein said member includes a volume-phase type hologram.

5. An apparatus according to claim 4, wherein said volume-phase type hologram of said relay member causes said beam to be reflectively diffracted.

6. An apparatus according to claim 5, wherein said volume-phase type hologram of said relay member comprises a polyvinyl carbazole.

7. An apparatus according to claim 3, wherein said volume-phase type hologram comprises a polyvinyl carbazole.

8. A system for transmitting a beam having a plurality of light wavelength components, comprising:

a first optical fiber for supplying the beam;

a second optical fiber for receiving the beam;

a first member forming a first diffraction grating for receiving and diffracting the beam from said first optical fiber, wherein a half-width of a wavelength spectrum of a diffraction efficiency of said first diffraction grating is set to be equal to or greater than 8% of a central wavelength of said wavelength spectrum; and

a second member forming a second diffraction grating for receiving and diffracting the beam from said first member and directing the beam to said second optical fiber, wherein a half-width of a wavelength spectrum of a diffraction efficiency of said second diffraction grating is smaller than that of said first diffraction grating.

9. A system according to claim 8, wherein said second optical fiber has a number of fibers which is the same as the number of light wavelength components, and each said optical fiber selectively receives one of the light wavelength components corresponding thereto.

10. A system according to claim 8, wherein at least one of said first member or said second member includes a substrate for supporting the diffraction grating forming a volume-phase type hologram.

11. A system according to claim 10, wherein said volume-phase type hologram causes the beams to be reflectively diffracted.

12. A system according to claim 10, wherein aid volume-phase type hologram comprises a polyvinyl carbazole.

13. A system for transmitting a beam having a plurality of light wavelength components from a first optical fiber to a second group of optical fibers, said system comprising:

a first member forming a first diffraction grating for receiving and diffracting the beam from said first optical fiber, wherein a half-width of a wavelength spectrum of a diffraction efficiency of said first diffraction grating is set to be equal to or greater than 8% of a central wavelength of said wavelength spectrum; and

a second member forming a second diffraction grating for receiving and diffracting the beam from said first member and directing the beam to said second group of optical fibers, wherein a half-width of a wavelength spectrum of a diffraction efficiency of said second diffraction grating is smaller than that of said first diffraction grating is smaller than that of said first diffraction grating.