Variable-focal-length lens

• US 4,564,267 A
• Filed: 12/27/1982
• Issued: 01/14/1986
• Est. Priority Date: 01/07/1982
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Nishimoto, Yoshifumi
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/453,161
• Time in Patent Office: 1,114 Days
• Field of Search: 350/347 E, 350/347 V, 350/356, 350/379, 350/384, 350/387-390, 350/393, 350/411, 350/413, 350/403, 354/400
• US Class Current: 359/484.02
• CPC Class Codes: G02B 15/00 Optical objectives with means for varying the magnification anamorphotic objectives G02B13/08
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/294 Variable focal length devices

Abstract

Disclosed is a variable-focal-length lens whose focal length can be electrically controlled by applying an electric field of uniform intensity distribution to a compound lens including at least one lens formed of electrooptic crystal and varying the intensity of the applied electric field.

Claims

1. A variable-focal-length lens comprising:

a lens system including at least one set of electrooptic crystals cemented together on curved surfaces thereof so that the directions of their respective axes of rotatory inversion are coincident with each other and so that the directions of their respective two corresponding rotation axes differ from each other;

means for applying an electric field of uniform intensity distribution to said cemented surfaces of said electrooptic crystals so as to make said cemented surfaces refraction surfaces having a lens action; and

means for varying the intensity of the electric field to be applied, to thereby vary the focal length of said lens system.

2. A variable-focal-length lens according to claim 1, wherein a polarizing plate is disposed on the light path of a light beam passing through said compound lens.

3. A variable-focal-length lens according to claim 1, wherein said means for applying an electric field comprises parallel flat electrodes attached to said electrooptic crystals.

4. A variable-focal-length lens according to claim 1, further comprising means provided on the light path of a light beam passing through said compound lens for varying the polarization direction of said light beam.

5. A variable-focal-length lens according to claim 3, wherein the intensity of the electric field to be applied is varied by controlling the voltage of a variable power source connected to said parallel flat electrodes.

6. A variable-focal-length lens according to claim 4, wherein said means for varying the polarization direction of said light beam comprises a polarizing plate and means for rotating said polarizing plate about the optical axis.