Vari-focal image pickup optical system for endoscopes

Details Vari-focal image pickup optical system for endoscopes Vari-focal image pickup optical system for endoscopes

1997-06-05

1999-08-03

Epps, Georgia

Optical: systems and elements

Lens

With variable magnification

359690, G02B 1514

Patent

active

059332824

ABSTRACT:
A vari-focal image pickup optical system for endoscopes comprising, in order from the object side, a first focusing lens unit which is capable of adjusting a diopter within a range covering positive and negative values, and has a positive refractive power, a second variator lens unit which has a vari-focal function and a negative refractive power, and a third compensator lens unit which maintains an image at a constant location by correcting a deviation of an image location caused by changing a magnification, wherein magnifications of the second lens unit and the third lens unit are changed around a magnification level of -1.times., wherein a magnification of the optical system is changed from that at a wide position to that at a tele position by moving the second lens unit from the object side toward the image side and moving the third lens unit from the image side toward the object side, and wherein the third lens unit is set at the magnification level of -1.times. when the second lens unit is set at the magnification level of -1.times.. The image pickup optical system is compact and light in weight, requires simple procedures for operation and can sufficiently cope with image pickup devices having picture elements arranged at high densities.

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