Achromatic lens for millimeter-wave and infrared bands
AssigneeHRL Laboratories, LLC
InventorsRobin J. Harvey, Franklin A Dolezal
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Abstract
The present invention relates to a method for designing an achromatic lens and a lens according to the design. The invention provides a lens that makes use of the differences in the index of refraction of ZnSe and ZnS in the mm-wave and IR wavebands to minimize the differences in focal position between the two wavebands. This lens train can be used in conjunction with a dual-band focal plane array to simultaneously focus two wavebands on a common focal plane and thus provide for simultaneous imaging in both wavebands.
Claims7
An multi element apparatus capable of simultaneously focusing a plurality of wavebands in substantially the same focal plane, comprising:
- i. a first element comprising a first composition and having a thickness, a perimeter, a first index of refraction, and a first and second surface substantially perpendicular to said perimeter wherein said first surface has a first geometry and wherein said second surface has a second geometry;
- ii. a second element comprising a second composition and having a thickness, a perimeter, a second index of refraction, and a first and second surface substantially perpendicular to said perimeter wherein said first surface has a third geometry and wherein said second surface has a fourth geometry;
- and
- iii. said first and second elements are aligned such that the second surface of the first element and the first surface of the second element are in substantial conformity with each other and aligned such that the perimeters essentially form a column, wherein
- the plurality of wavebands include millimeter wave radiation and infrared radiation, wherein:
- i. millimeter wave radiation is between 30 GHz and 300 GHz;
- and
- ii. infrared radiation is between 0.75 and 750 micrometers.
A multi element lens capable of simultaneously focusing on a plurality of wavebands in substantially the same focal plane, comprising:
- i. a first element comprising a first composition and having a first thickness, a first perimeter, a first index of refraction unique to the waveband passing though the element, and a first and second surface substantially perpendicular to said perimeter wherein said first surface has a first radius and wherein said second surface has a second radius;
- ii. a second element comprising a second composition and having a second thickness, a second perimeter, a second index of refraction unique to the waveband passing though the element, and a first and second surface substantially perpendicular to said perimeter wherein said first surface has a third radius and wherein said second surface has a fourth radius;
- and
- iii. said first and second elements are aligned such that the second surface of the first element and the first surface of the second element are in substantial conformity with each other and aligned such that the perimeters essentially form a column;
- and wherein
- a. said first radius is a negative 54 cm;
- b. said second radius is a positive 24 cm;
- c. said third radius is a negative 42.9 cm;
- d. said fourth radius is a positive 29.94 cm;
- e. said first index of refraction is 2.3 for infrared radiation and 2.9 in for mm-wave radiation;
- f. said second index of refraction is 2.4 for infrared radiation and 3.0 for mm-wave radiation.
Dependencies are inferred from the claim text.