ZOOM LENS PROVIDED WITH TEMPERATURE CHANGE CORRECTING FUNCTION

Title:

ZOOM LENS PROVIDED WITH TEMPERATURE CHANGE CORRECTING FUNCTION

Document Type and Number:

Japanese Patent JP3862117

Kind Code:

B2

Abstract:

PROBLEM TO BE SOLVED: To restrain the difference of the moving amount of a focal position due to temperature change by setting the temperature coefficient of the refractive index of glass material within a specified range for two kinds of specified lenses in an EXT group so that the moving amount of the focal position associated with the temperature change by two kinds of lenses may be cancelled each other.
SOLUTION: EXT all groups L22 to L25 are constituted of two biconvex lenses L22 and L23 and a combined lens consisting of the biconvex lens L24 and the biconcave lens L25. EXT rear groups L26 to L27 are constituted of the combined lens consisting of the biconcave lens L26 and the positive meniscus lens L27. Assuming that the temperature coefficient of the refractive index of the lens L25 is P1 and that of the refractive index of the lens L27 is P2, P1<3.0 and P2>12.0 (provided that P1 and P2 mean dn/dt relative(×10-6/°C) when the wavelength of light is an e-line) are satisfied, and assuming that the Abbe number of the single lenses L22 and L23 is ν1, ν1≥80 is satisfied.

Inventors:

Kazuo Yoshikawa

Application Number:

JP33941797A

Publication Date:

December 27, 2006

Filing Date:

November 25, 1997

Export Citation:

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