| 摘要 |
<p>An ultra-wide band achromatic lens which provides simultaneous multiband coverage from the visible to the very near infrared range of the energy spectrum. The lens (10) is made of three alternating elements 12, 14 and 16 of calcium fluoride or magnesium oxide in relative optical alignment. In a first embodiment, the elements are arranged in a Cooke triplet with a first positive (convergent) element 12 of calcium fluoride, a second negative (divergent) element 14 of magnesium oxide, and a third positive element 16 of calcium fluoride. In a second embodiment, a wide-angle triplet is provided with a first negative element 12 of magnesium oxide, a second positive element 14 of calcium fluoride, and a third element 16 of magnesium oxide. In both embodiments, the invention provides an achromatic optical system which is simultaneously corrected for chromatic and other aberrations over the multiband wavelength range from the visible to the very near infrared portion of the energy spectrum, i.e., .5 microns to 5 microns. <IMAGE></p> |
