초록 ▼

A modified Schwarzschild Casegrainian objective reflects radiant energy between the primary and secondary mirror two times to form a four reflection optical path. The four reflection optical path increases the magnification of the objective without making the working distance that separates the seco

A modified Schwarzschild Casegrainian objective reflects radiant energy between the primary and secondary mirror two times to form a four reflection optical path. The four reflection optical path increases the magnification of the objective without making the working distance that separates the secondary mirror from the sample unacceptably small. The four reflection optical path maintains good image quality at high numerical aperture due, at least in part, to the relatively small size of a microscopic object. The objective functions as a zoom lens by changing the location of a remote field stop along the optical axis of the objective and refocusing because the emerging beam of radiant energy is nearly collimated along the optical axis at the field stop. The reflecting objective also obtains variable magnification by converting to a two reflection mode of operation by increasing the separation of the primary mirror from the secondary mirror from the sample image plane. The two reflection mode provides for less magnification than obtained with the four reflection mode.

대표청구항 ▼

A reflecting microscope objective selectively having a two reflection or a four reflection magnification mode, comprising: a remote field stop positioned along an optical axis; a primary mirror having a concave spherical curvature and being positioned along the optical axis, said primary mirror havi

A reflecting microscope objective selectively having a two reflection or a four reflection magnification mode, comprising: a remote field stop positioned along an optical axis; a primary mirror having a concave spherical curvature and being positioned along the optical axis, said primary mirror having an on-axis hole therethrough and a center of curvature; a secondary mirror having a convex spherical curvature with a center of curvature and being positioned along the optical axis in spaced relationship from the primary mirror to provide a separation therebetween, means to change the separation distance between the primary mirror and the secondary mirror from a first separation distance for the four reflection mode to a second separation distance for the two reflection mode or vice versa; a first sample image plane positioned along the optical axis and being separated by a finite first working distance from the secondary mirror; a second alternate sample image plane positioned along the optical axis and being separated by a finite second working distance from the secondary mirror; the four reflection mode occurring when the primary mirror and secondary mirror are spaced apart the first separation distance, said first sample image plane being closer to said primary mirror than said remote field stop is to said secondary mirror, said secondary mirror having its center of curvature displaced slightly toward said primary mirror with respect to said center of curvature of said primary mirror, whereby said first separation distance and said first working distance are such as to form a four reflection optical path extending from said first sample image plane to said primary mirror, from said primary mirror to said secondary mirror, from said secondary mirror to said primary mirror, from said primary mirror to said secondary mirror and from said secondary mirror through said on-axis hole to said remote field stop; and the two reflection mode occurring when the space between said primary mirror and said secondary mirror has been changed by said means to change to the second separation distance, whereby said second working distance and said second separation distance are such as to form a two reflection optical path extending from the second sample image plane to the primary mirror, from the primary mirror to the secondary mirror and from the secondary mirror through said on-axis hole to said remote field stop.