Patent ID: 7927273
Filing Date: 2011-04-19
Classification: A61B,G02B

Abstract:
1. An image pickup unit for picking up magnified images of an object, comprising: an objective optical system having an image scale factor with an absolute value greater than unity and an image pickup element, wherein the following condition is satisfied where p is the pixel size of the image pickup element, NA is the numerical aperture, λ is the wavelength at the e-line (546.1 nm), and βo is the image scale factor of the objective optical system, wherein: the objective optical system includes, in order from the object side, a front unit having positive refractive power, an aperture stop and a rear unit having positive refractive power, and the following condition is satisfied where f2 is the focal length of the rear unit, and f1 is the focal length of the front unit.