Optical: systems and elements – Lens – Multiple component lenses
Patent
1997-06-27
1998-05-26
Ben, Loha
Optical: systems and elements
Lens
Multiple component lenses
359798, 359663, 396 89, 362297, 250548, G02B 904
Patent
active
057575584
ABSTRACT:
The optical unit of an imaging system is disposed between a target object and an image plane, and permits the passage of cones of light from different point sources on the target object therethrough to form an image on the image plane. The optical unit is provided with an aperture stop to control sizes of the cones of light passing through the optical unit. The aperture stop forms an entrance pupil in relation to the optical unit. A rectifying mask, which is formed as an upright opaque plate, is disposed between the target object and the image plane. The aperture stop forms a corresponding aperture stop image on a plane of the rectifying mask, and the rectifying mask has a mask width which is narrower than the width of the corresponding aperture stop image, and a mask height which is greater than the mask width. The rectifying mask or a mask image thereof as formed by the optical unit appears to shift relative to the entrance pupil such that the rectifying mask or the mask image thereof covers different areas of the entrance pupil when a center of the entrance pupil is viewed from the different point sources on the target object, thereby resulting in generally uniform illumination reduction at the image plane to compensate for the cosine-fourth law phenomenon.
REFERENCES:
patent: 4943733 (1990-07-01), Mori et al.
patent: 5046837 (1991-09-01), Sroomer et al.
patent: 5193124 (1993-03-01), Subbarao
patent: 5424877 (1995-06-01), Tsuyuki et al.
Ben Loha
E-Lux Inc.
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