Title:
FOCUSING DEVICE
Document Type and Number:
Japanese Patent JPH04113305
Kind Code:
A
Abstract:
PURPOSE:To perform focusing operation by irradiating an object with light beam flux while the optical axis is aligned with the axis of an objective, passing its reflected light through a cylindrical lens and photodetecting the light, and detecting defocusing from the shape of its spot and varying the distance between the object and objective according to the defocusing quantity. CONSTITUTION:The object W is irradiated with the light beam flux from a light source 9 after the light beam flux passes the axis of the objective 5, and its reflected light beam flux is transmitted through the objective 5 and cylindrical lens 15 and made incident on a CCD camera 17. The spot shape of the luminous flux is discriminated to detect the defocusing and a stepping motor 19 is driven according to the detection result to vary the distance between the surface of a work W and the objective, thereby focusing the light flux. Consequently, the focusing position can be made constant regardless of the focusing operation and an optical system can easily be assembled in a short time.
Inventors:
UTO MASAHIKO
HASEGAWA HIROYUKI
TAKEI RIKAKO
HASEGAWA HIROYUKI
TAKEI RIKAKO
Application Number:
JP23411190A
Publication Date:
April 14, 1992
Filing Date:
September 03, 1990
Export Citation:
Assignee:
BROTHER IND LTD
International Classes:
G02B7/28; (IPC1-7): G02B7/28