Title:
MULTI-FREQUENCY MEASURING APPARATUS FOR FOCUS CONTROL
Document Type and Number:
Japanese Patent JPS5837612
Kind Code:
A
Abstract:
A photoplotter includes an autofocus control for maintaining a precise focal distance between a photohead in the plotter and the film surface which is exposed by the head. The autofocus control employs a dual frequency ultrasonic ranging apparatus which permits coarse focus control at one frequency and fine focus control at a second, higher frequency.
Inventors:
HENRII EFU BAADATSUTO
KERII DEII BEINZU
KERII DEII BEINZU
Application Number:
JP13836982A
Publication Date:
March 04, 1983
Filing Date:
August 09, 1982
Export Citation:
Assignee:
GERBER SCIENTIFIC INSTR CO
International Classes:
G03B13/36; G01S15/36; G02B7/40; (IPC1-7): G02B7/11; G03B3/00
Attorney, Agent or Firm:
Kyozo Yuasa
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