Re-imaging converter lens apparatus and method

A re-imaging optical system for use with a prime lens having a field angle and capable of forming a primary image on a primary image plane, the re-imaging optical system comprising:

• (a) a field lens group adapted to be disposed coaxially imagewise relative to the primary image plane;
• and
• (b) an optical relay disposed coaxially imagewise relative to the field lens group, the optical relay being operative to transfer and positively demagnify substantially the entire primary image from the primary image plane to a secondary image plane situated imagewise relative to the optical relay, without reducing the field angle of the prime lens, the optical relay comprising (i) a first lens group disposed coaxially imagewise of the field lens group, the first lens group having a negative refracting power and a focal length f.sub.2, each lens element in the first lens group having negative refractive power having an Abbe number V.sub.d >45;
• (ii) a second lens group disposed coaxially imagewise of the first lens group, the second lens group having a positive refracting power and a focal length f.sub.3, and comprising a negative meniscus lens element disposed as the most objectwise lens element in the second lens group, the negative meniscus lens element having an objectwise surface and an imagewise surface each having a radius of curvature of r.sub.1 and r.sub.2, respectively, wherein 2<(r.sub.1 +r.sub.2)/(r.sub.1 -r.sub.2)<50;
• and (iii) an erecting lens group interposed coaxially between the first and second lens groups.

An apparatus for re-imaging a primary image, the primary image being produced at a primary image plane by a prime lens having a field angle, the apparatus comprising:

• (a) a field lens group situated coaxially imagewise of the primary image plane;
• (b) a negative lens group having a focal length f.sub.2 situated coaxially imagewise of the field lens group and comprising a negative lens element having an Abbe number V.sub.d >45;
• (c) an erecting lens group situated coaxially imagewise of the negative lens group;
• (d) a positive lens group situated coaxially imagewise of the erecting lens group, the positive lens group having a focal length f.sub.3 and comprising a negative meniscus lens element disposed as the most objectwise lens element in the positive lens group, the negative meniscus lens element having an objectwise surface and an imagewise surface having a radius of curvature of r.sub.1 and r.sub.2, respectively, wherein 2<(r.sub.1 +r.sub.2)/(r.sub.1 -r.sub.2)<50, the positive lens group having a principal point separated from the secondary image plane by a distance DB.sub.f, wherein 0.5<.vertline.f.sub.3 /DB.sub.f .vertline.<1.0;
• (e) an aperture stop situated coaxially between the erecting lens group and the positive lens group at a distance D from an objectwise surface of a lens element in the positive lens group nearest the aperture stop, wherein 0.2<.vertline.D/f.sub.2 .vertline.<0.7;
• (f) at least one of the positive and negative lens groups comprising a positive lens element having a refractive index n.sub.c satisfying the condition:
• n.sub.c >1.7;
• (g) the negative lens group, the erecting lens group and the positive lens group collectively comprising an optical relay adapted to transfer and positively demagnify substantially the entire primary image from the primary image plane to form a secondary image on a secondary image plane, situated imagewise relative to the positive lens group, without reducing the field angle of the prime lens, the optical relay having a focal length f.sub.r satisfying the condition 3<.vertline.f.sub.2 /f.sub.r .vertline.<4;
• and
• (h) a beam splitter disposed coaxially imagewise relative to the positive lens group, the beam splitter serving to conduct the secondary image along multiple pathways to form multiple secondary images at multiple secondary image planes.

An apparatus adapted to be disposed coaxially imagewise relative to a prime lens for re-imaging a primary image produced at a primary image plane by the prime lens, the prime lens having a field angle, the apparatus comprising:

• (a) a field lens group;
• (b) a negative lens group situated coaxially imagewise of the field lens group, the negative lens group having a focal length f.sub.2 ;
• (c) an erecting prism situated coaxially imagewise of the negative lens group;
• (d) an aperture stop situated coaxially imagewise of the erecting prism;
• (e) a positive lens group situated coaxially imagewise of the aperture stop and having a focal length f.sub.3, the positive lens group comprising a negative meniscus lens element situated as the most imagewise lens element in the positive lens group, the negative meniscus lens element having an objectwise surface and an imagewise surface each having a radius of curvature of r.sub.1 and r.sub.2, respectively, wherein 2<(r.sub.1 +r.sub.2)/(r.sub.1 -r.sub.2)<50;
• (f) the negative lens group, the erecting prism, the aperture stop, and the positive lens group being collectively operable as an optical relay for transferring and positively demagnifying substantially the entire primary image from the primary image plane so as to form a secondary image on a secondary image plane, situated imagewise relative to the positive lens group, without substantially reducing the field angle of the prime lens, the optical relay having a focal length f.sub.r, wherein 3<.vertline.f.sub.2 /f.sub.r .vertline.<4.