Title:
OPTICAL SYSTEM OF ILLUMINATION FOR EXPOSING DEVICE
Document Type and Number:
Japanese Patent JPS5943521
Kind Code:
A
Abstract:
PURPOSE:To contrive improvement in the resolving property of a projection optical system by a method wherein, in the case of a transparent sheet glass for scattering having directivity which is placed in an optical path, no change is made in the thickness of the plate glass to be used for the beam of light in longitudinal direction, and a roughened surface is provided for the sheet glass to be used for the beam of light in sphereless direction, thereby enabling to increase the non-coherence property of the beam of light in sphereless direction. CONSTITUTION:The beam of light in sphereless direction alone is scattered and no scattering is generated for the beam of light in longitudinal direction. To be more precise, a transparent scattering sheet glass is placed in an optical path and no scattering is generated unless a change is made in the thickness of the sheet glass, as shown in the diagram (a), and on the other hand, scattering is generated for the beam of light in sphereless direction as shown in the diagram (b) by providing irregular surface. In order to generate the scattering of light as above-mentioned with the plate glass having the thickness of (t) as shown in the diagram (c), the formula t(gamma, theta)=f(theta) is used. Also, theta is changed to periodic function in order to reduce the non-uniformity of the irradiated light in circular arc.
Inventors:
SHIBA MASATAKA
OSHIDA YOSHISADA
OSHIDA YOSHISADA
Application Number:
JP15270182A
Publication Date:
March 10, 1984
Filing Date:
September 03, 1982
Export Citation:
Assignee:
HITACHI LTD
International Classes:
G03B27/54; G03F7/20; H01L21/027; H01L21/30; (IPC1-7): G03B27/32
Attorney, Agent or Firm:
Toshiyuki Usuda