Title:
BEAM EXPANDER AND OPTICAL HEAD USING THE SAME
Document Type and Number:
Japanese Patent JPH04362608
Kind Code:
A
Abstract:
PURPOSE:To expand the beam diameter of parallel light by an afocal optical system which has short overall lens length while holding the light parallel by setting a specific condition for the overall length of the afocal optical system, the expansion rate of the diameter of the beam, and the diameter of the projection beam. CONSTITUTION:In the afocal optical system which expands the parallel incident beam and emits the parallel light, a 1st lens with negative power and a 2nd lens with positive power is arranged from the incidence side. When the incident beam is transmitted through the 1st lens having an aspherical surface and the 2nd lens, the condition shown by an inequality is satisfied. In the inequality, L is the overall length of the lens, D is the emitting beam diameter, and (m) is the expansion rate. This constitution corrects a spherical aberration and a sine condition even when the overall lens length is shortened to hold a wave front aberration within a diffraction limit. Consequently, the compact, high- performance beam expander which consists of one or two lenses and has short overall lens length is obtained.
Inventors:
TANAKA YASUHIRO
Application Number:
JP13910891A
Publication Date:
December 15, 1992
Filing Date:
June 11, 1991
Export Citation:
Assignee:
MATSUSHITA ELECTRIC IND CO LTD
International Classes:
G02B9/00; G02B13/18; G02B27/00; G02B27/09; (IPC1-7): G02B9/00; G02B13/18; G02B27/00
Attorney, Agent or Firm:
Akira Kobiji (2 outside)