Patent
1986-10-14
1988-07-05
Corbin, John K.
350432, 350469, G02B 300, G02B 318, G02B 934
Patent
active
047550287
ABSTRACT:
A projection lens for a cathode ray tube consisting from the image end of a first lens unit including an element of overall meniscus shape and of positive power at the optical axis, the first lens unit has an object side surface convex to the aperture stop, a second lens unit which consists of a biconvex element and supplies the majority of the positive optical power of the lens, the biconvex element beng of glass and having spheric surfaces, a third lens unit adjacent the cathode ray tube having a strongly concave image side surface and serving as a field flattener, the axial spacing between the first lens unit and said second lens unit also contributing to correction of field curvature, and a corrector lens unit having image side surface convex toward the aperture stop. The surfaces of the first lens unit and the corrector lens unit which are both convex to the aperture stop contribute to correction of sagittal oblique spherical aberration. The corrector unit is axially spaced from the second lens unit a distance such that the axial marginal rays from the second lens unit, as traced from the long conjugate, side intersect the image side surface of the corrector unit at a height from the optical axis that is less than the clear aperture of said corrector lens unit. The corrector lens unit is shaped to correct for off-axis aberrations above the intersection. The first lens unit is of a power which will coverage rays as traced from the long conjugate and thereby reduce the diameter of the second lens unit.
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Printed Publication-Diagram of a Lens Entitled, Advent Lens Mod II.
Printed Publication-pp. 470-482 of a volume Entitled, A System of Optical Design, by COX.
Corbin John K.
Kachmarik Ronald M.
U.S Precision Lens, Incorporated
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