Diffractive optical element and optical system including the same

• US 5,737,125 A
• Filed: 10/31/1995
• Issued: 04/07/1998
• Est. Priority Date: 10/27/1992
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Ohashi, Hitoshi
• Primary Examiner(s): Henry, Jon W.
• Application Number:
  US08/555,222
• Time in Patent Office: 889 Days
• Field of Search: 359/16, 359/565, 359/566, 359/568, 359/575, 359/573, 359/19, 359/885, 359/570
• US Class Current: 359/565
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08

Abstract

An optical system for use in a relatively wide wavelength range including a plurality of diffractive optical elements whose diffraction efficiencies are optimized for different wavelengths within said predetermined wavelength range. A diffractive optical element for use in a wide wavelength range includes a light transmissive substrate having a plurality of surface regions and a plurality of surface relief diffractive gratings are formed in said surface regions such that diffraction efficiencies of these gratings are optimized for different wavelengths within said predetermined wavelength range. A diffractive optical element is formed by a single optical element having a light transmissive substrate which reveals a given spectral transmittance and a surface relief diffractive grating formed in a surface of said substrate such that a wavelength dependency of said grating provides a desired spectral transmittance together with said spectral transmittance of the substrate.

Claims

1. An optical system for use in a predetermined wavelength range, said optical system comprising:

at least one diffractive optical element having a given wavelength dependency of diffraction efficiency so as to have a first spectral transmittance; and

at least one optical element having a second spectral transmittance characteristics which, together with said first spectral transmittance, provides a desired overall spectral transmittance which is flatter over said predetermined wavelength range than either said first spectral transmittance or said second spectral transmittance.

2. An optical system according to claim 1, wherein said diffractive-optical element is formed by a surface relief diffractive grating whose diffraction efficiency is optimized for a wavelength within said predetermined wavelength range, and said optical element is made of a material having the second spectral transmittance which is substantially complementary to the wavelength dependency of diffraction efficiency of said surface relief diffractive grating.

3. An optical system according to claim 2, wherein said optical element comprises a color compensation filter.

4. An optical system according to claim 1, wherein said at least one diffractive optical element comprises a blazed diffractive surface.

5. An optical element according to claim 2, wherein said surface relief diffraction grating comprises a blazed diffractive surface.

6. An optical element according to claim 3, wherein said diffractive optical element comprises a blazed diffractive surface.

7. An optical system according to claim 1, wherein said at least one diffractive optical element is optimized to maximize a diffraction efficiency for first-order diffracted light.