Optical relay system
A spectrally shearing optical relay system, said relay system being comprised of two halves disposed symmetrically about an aperture stop S, wherein each half comprises a plurality of rotationally symmetric optical elements forming an objective and a com-pound prism comprised of a plurality of dispersing prisms. The compound prisms are located between the objectives and the aperture stop. An imaging device with such an optical relay system is also proposed.
1 . A spectrally shearing optical relay system, said optical relay system being comprised of two halves disposed symmetrically about an aperture stop, wherein each one of the two halves comprises a plurality of rotationally symmetric optical elements forming an objective and a compound prism comprised of a plurality of dispersing prisms,
wherein the compound prisms are located between the objectives and the aperture stop,
wherein at least one of the following conditions is met:
the plurality of prisms forming the compound prisms have a small difference in refractive index at the center wavelength, and
the plurality of prisms has a larger difference in refractive index at the end points of the spectral range,
and wherein two measures of refractive index dispersion are defined as follows:
v 700=( n 700−1)/( n 400− n 700),
P 700=( n 400− n 700)/( n 400− n 1000)
where n 400 , n 700 , and n 1000 are the refractive indices at 400 nm, 700 nm, and 1000 nm,
and wherein the objective is comprised of five rotationally symmetric lens elements (L 1 , L 2 , L 3 , L 4 , L 5 ), wherein a first lens element and a second lens element (L 1 , L 2 ) form a first doublet (D 1 ), a third lens element and a fourth lens element (L 3 , L 4 ) form a second doublet (D 2 ), and a fifth lens element is a positive singlet, the objective satisfying the following expressions:
1.73<Φ D1 /Φ objective <−1.57
0.92<Φ D2 /Φ objective <1.01
0.89<Φ L5 /Φ objective <0.98
n 700 for L 1 >1.85
|ΔP 700 /Δv 700 |<0.007 for D 1
|ΔP 700 /Δv 700 |<0.0001 for D 2
v 700 for L 5 >24,
where Φ objective is the optical power of the objective, Φ D1 is the optical power of the first doublet (D 1 ), Φ D2 is the optical power of the second doublet (D 2 ), Φ L5 is the optical power of the singlet (L 5 ), and ΔP 700 /Δv 700 for a doublet is the difference in P 700 divided by the difference in v 700 for the two glasses comprising the doublet.
2 . The spectrally shearing optical relay system according to claim 1 , where the bundles of light incident on the compound prism are collimated.
3 . The spectrally shearing optical relay system according to claim 1 , where at least one of the following conditions is met:
the compound prisms show essentially zero deviation of the axial chief ray at the center wavelength, and
the chief rays at the end points of the spectral range are deviated to spectrally shear the image.
4 . The spectrally shearing optical relay system according to claim 1 , wherein
the difference in refractive index at the center wavelength is <0.001.
5 . The spectrally shearing optical relay system according to claim 4 , wherein the difference in refractive index between either endpoint of the spectral range and the center wavelength is between 0.003 and 0.007.
6 . The spectrally shearing optical relay system according to claim 1 , wherein the external faces of the compound prisms are perpendicular to the optical axis.
7 . The spectrally shearing optical relay system according to claim 6 , wherein the external faces of the compound prisms are substantially perpendicular to the optical axis to within 0.1°.
8 . The spectrally shearing optical relay system according to claim 1 , wherein the first and second doublets (D 1 , D 2 ) comprise one glass with anomalous partial dispersion.
9 . The spectrally shearing optical relay system according to claim 8 , wherein the fifth lens element has a weak aspheric surface.
10 . The spectrally shearing optical relay system according to claim 1 , wherein the compound prisms are corrected for use between 400 nm and 1000 nm, and wherein the compound prisms are comprised of an exterior prism element and an interior prism element made from one of the following combinations:
Schott N-SK4 for the exterior prism element and Schott N-KzFS4 for the interior prism element or equivalent glasses from other manufacturers,
Schott N-BAF51 for the exterior prism element and Schott N-KzFS5 for the interior prism element or equivalent glasses from other manufacturers, or
Schott N-BK10 for the exterior prism element and Schott N-PK52A for the interior prism element or equivalent glasses from other manufacturers.
11 . The spectrally shearing relay system according to claim 1 , wherein the spectrally shearing relay system is telecentric on an object side and an image side.
12 . The spectrally shearing optical relay system according to claim 1 being corrected for use between from 900-1700 nm.
13 . The spectrally shearing optical relay system according to claim 12 , wherein the compound prisms are comprised of an exterior prism element and an interior prism element made Schott N-SF66 for the exterior prism element and Schott N-LASF31A for the interior prism element or equivalent glasses from other manufacturers.
14 . An imaging device comprising an optical relay system, wherein the optical relay system comprises two halves disposed symmetrically about an aperture stop, wherein each one of the two halves comprises a plurality of rotationally symmetric optical elements forming an objective and a compound prism comprised of a plurality of dispersing prisms, and wherein the compound prisms are located between the objectives and the aperture stop,
wherein at least one of the following conditions is met:
the plurality of prisms forming the compound prisms have a small difference in refractive index at the center wavelength, in particular the difference in refractive index at the center wavelength is <0.001, and
the plurality of prisms has a larger difference in refractive index at the end points of the spectral range, and
wherein two measures of refractive index dispersion are defined as follows:
v 700=( n 700−1)/( n 400− n 700),
P 700=( n 400− n 700)/( n 400− n 1000)
where n 400 , n 700 , and n 1000 are the refractive indices at 400 nm, 700 nm, and 1000 nm, and wherein the objective is comprised of five rotationally symmetric lens elements (L 1 , L 2 , L 3 , L 4 , L 5 ), wherein a first lens element and a second lens element (L 1 , L 2 ) form a first doublet (D 1 ), a third lens element and a fourth lens element (L 3 , L 4 ) form a second doublet (D 2 ), and a fifth lens element is a positive singlet, wherein the objective satisfies the following expressions:
−1.73<Φ D1 /Φ objective <−1.57
0.92<Φ D2 /Φ objective <1.01
0.89<Φ L5 /Φ objective <0.98
n 700 for L 1 >1.85
|ΔP 700 /Δv 700 |<0.007 for D 1
|ΔP 700 /Δv 700 |<0.0001 for D 2
v 700 for L 5 >24,
where Φ objective is the optical power of the objective, Φ D1 is the optical power of the first doublet (D 1 ), Φ D2 is the optical power of the second doublet (D 2 ), Φ L5 is the optical power of the singlet (L 5 ), and ΔP 700 /Δv 700 for a doublet is the difference in P 700 divided by the difference in v 700 for the two glasses comprising the doublet.