Patent ID: 6313952
Filing Date: 2001-11-06
Classification: G02B

Abstract:
An adapter lens attachable to an imaging lens side of a Greenough stereomicroscope for viewing an object through eyepieces of the stereomicroscope arranged at an eyepiece level, the adapter lens comprising:a first lens having positive refracting power; anda second lens having negative refracting power and separated from said first lens by a variable distance, whereinsaid distance is varied so as to continuously change the eyepiece level with respect to an object under observation between a first position and a second position;said first position is a high-eye-level position representing a state where an eye point position along optical axes of eye-pieces of the stereomicroscope, equipped with said adapter lens, are placed at a farthest position from the object;said second position is a low-eye-level position representing a state where said eye point position along the optical axes of the eye-pieces of the stereomicroscope, equipped with said adapter lens, are placed at a nearest position from the object;at said low-eye-level position .beta.4L.times..beta.5L>1, D54L+D51L/(.beta.4L.times..beta.5L)-D54L/.beta.4L-D51L<0; andat said high-eye-level position .beta.4.times.5H<1, D54H+D51H/(4H.times..beta.5H)-D54H/.beta.4H-D51H>0, wherein .beta.4L represents a magnification of said second lens at said low-eye-level position, .beta.5L represents a magnification of said first lens at said low-eye-level position, .beta.4H represents a magnification of said second lens at said high-eye-level position, .beta.5H represents a magnification of said first lens at said high-eye-level position, D54L represents a distance between a principal plane of said first lens and a principal plane of said second lens at said low-eye-level position, D54H represents a distance between said principal plane of said first lens and said principal plane of said second lens at said high-eye-level position, D51L represents a distance between said principal plane of said first lens at said low-eye-level position and an object position of the stereomicroscope not equipped with said adapter lens, and D51H represents a distance between said principal plane of said first lens at said high-eye-level position and said object position of the stereo microscope not equipped with said adapter lens.