Large field of view, high numerical aperture compound objective lens with two pairs of identical elements and near IR spectrometer containing two such compound lenses
First Claim
Patent Images
1. A compound lens comprising:
- exactly four lenses, wherein a shape of the first lens is essentially identical to a shape of the fourth lens, and a shape of the second lens is essentially identical to a shape of the third lens;
wherein the compound lens has a numerical aperture greater than 0.25;
wherein the compound lens has a field of view of at least 25% of the compound lens focal length; and
wherein an angular frequency at which a modulation transfer function exceeds 0.5 is at least 0.3 cycles per milliradian.
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Abstract
An apparatus consisting of two pairs of identical lenses which is suitable as a compound objective lens for high numerical aperture imaging is disclosed. The compound lens also has a wide field of view as a fraction of the compound lens focal length. By suitable choice of lens materials, well corrected near infrared imaging can be achieved. When two such compound lenses together with a diffraction grating are assembled into a spectrometer, excellent wavelength resolution in the near infrared can also be obtained.
37 Citations
14 Claims
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1. A compound lens comprising:
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exactly four lenses, wherein a shape of the first lens is essentially identical to a shape of the fourth lens, and a shape of the second lens is essentially identical to a shape of the third lens; wherein the compound lens has a numerical aperture greater than 0.25; wherein the compound lens has a field of view of at least 25% of the compound lens focal length; and wherein an angular frequency at which a modulation transfer function exceeds 0.5 is at least 0.3 cycles per milliradian. - View Dependent Claims (2, 3, 4, 5)
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6. A spectrometer comprising:
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a first compound lens comprising exactly four lenses, wherein a shape of the first lens is essentially identical to a shape of the fourth lens, and a shape of the second lens is essentially identical to a shape of the third lens; a diffraction grating positioned to receive light from an optical input that passes through the first compound lens; and a second compound lens comprising exactly four lenses, wherein a shape of the first lens is essentially identical to a shape of the fourth lens, and a shape of the second lens is essentially identical to a shape of the third lens, the second compound lens positioned to receive light diffracted from the diffraction grating, wherein the first and second compound lenses have numerical apertures greater than 0.25; wherein the first and second compound lenses have field of views of at least 25% of the compound lens focal length; and wherein the first and second compound lenses comprise a measure of resolution defined by a product of a minimum spatial frequency at which a modulation transfer function exceeds 0.5 and the respective compound lens focal length exceeds 400, for everywhere in the respective compound lens field of view. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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Specification