Optical illumination system

Claim 2

An aircraft mounted ground illumination system for an optical lens system comprising: a plurality of illumination modules, each comprising a cylindrical light source and a trough-like reflector having a rectangular beam aperture and a pair of curved reflective surfaces parallel with the geometric axis of said cylindrical light source and formed to provide reflected light distribution weighted in a plane perpendicular to the geometric axis of said light source, at least a first one of said illumination modules being arranged with its axis parallel to a given direction so as to provide light distribution weighted in a plane perpendicular to said given direction, and at least a second one of said illumination modules being arranged with its axis perpendicular to said given direction so as to provide light distribution weighted in a plane parallel to said given direction, at least said first and second illumination modules illuminating in common at least a predetermined portion of a desired ground-imaged format additively in accordance with the expression I Io sec2 theta secn phi where I is radiant light intensity, Io is the value of radiant intensity at the nadir, theta is the slant range angle to said portion as measured from the nadir, phi is the optical lens fall-off angle to said portion as measured from the optical axis of said desired format, and n is an exponent indicative of the off-axis optical characteristic of the optical lens used.

Claim 3

An optical illumination system as defined in claim 1 wherein each of said illumination modules has at least one curved reflective surface which is parallel to the axis of said cylindrical light source and which extends through a series of points, said reflective surface at each of said points being spaced from the geometric axis of said cylindrical light source and having a slope reflecting the tangentially-emitted incident ray nearer the aperture of the reflector at a predetermined half-beam-width angle relative to a center plane defined by the geometric axis of the light source and the center line of illumInation beam aperture of said reflector for incidence upon the opposite outermost edge of the illumination format, the spacing of said points from the geometric axis of said cylindrical light source being increased at each successive one of said points to diminish the divergence angle of the reflected rays at each successive one of said points in said series from a predetermined maximum angle at the first point in said series to a predetermined minimum angle at the last point in said series.

Claim 4

An optical illumination system as defined in claim 5 wherein each of said illumination modules has a pair of curved reflective surface regions symmetrical with one another about a median plane defined by the geometric axis of said cylindrical light source and the center line of the illumination beam aperture of said reflector, each of said reflective surfaces extending through a series of points, the reflective surface at each of said points being spaced from the geometric axis of said cylindrical light source and having a slope reflecting the tangentially-emitted incident ray nearer the aperture of the reflector at a predetermined half-beam-width angle relative to said median plane for incidence upon the opposite outermost edge of the illumination format, the spacing of said points from the geometric axis of said cylindrical light source being increased at each successive one of said points to diminish the divergence angle of the reflected rays at each successive one of said points in said series from a predetermined maximum angle at the first point in said series to a predetermined minimum angle at the last point in said series.

Claim 5

An optical illumination system as defined in claim 1 further comprising: an intake for cooling air; manifold means for distributing cooling air from said intake to said illumination modules, each of said illumination modules having an optically transparent quartz tube within which said cylindrical illumination source is coaxially disposed; means for conducting cooling air from said manifold means to one end of said quartz tube; and means for exhausting cooling air from the opposite end of said quartz tube.

Claim 6

An optical illumination system as defined in claim 4 wherein each of said illumination modules includes electrical connection clips for the electrodes of said cylindrical light source, said connection clips having a plurality of radial fins interposed in the cooling air flow through said quartz tube.

Claim 7

An optical illumination unit comprising: a cylindrical light source, and a trough-like reflector having a rectangular beam aperture and having at least one curved reflective surface which is parallel to the axis of said cylindrical light source and which extends through a series of points; the distance Ls of said reflective surface from the geometric axis of said cylindrical light source at the first (rearwardmost) point in said series being defined by the expression Ls R/arctan ((Js - Ks)/2) wherein R is the radius of said cylindrical light source, Js is the predetermined half-beam-width angle, and Ks is a selected angle which is less than a half-beam-width angle; the slope Ys of said reflective surface at said first point in said series being defined by the expression Ys (Js + Ks +2Xs)/4 wherein Xs is the polar coordinate angle of said first point Ps in said series as related to the geometric axis of said cylindrical light source and as measured from a center plane passed through the geometric axis of the light source and the center line of the illumination beam aperture of said reflector; the slope Yn of said reflective surface at every other point Pn in said series being defined by the expression Yn (Jn + Kn + 2Xn)/4 wherein Jn iS constant equal to the half-beam-width angle Js, Kn is an angle selected to have the characteristic Kn>Kn 1 >Ks, and Xn is the polar coordinate angle of the point Pn with Xn having the characteristic Xn Delta X + Xn 1; the distance Ln of said reflective surface from the geometric axis of said cylindrical light source at Pn being defined by the expression Ln Ln 1 (1 + sin Delta X tan (Xn 1 + ( Delta X/2) - Yn 1)).

Claim 8

An optical illumination unit comprising: a cylindrical light source, and a trough-like reflector having a rectangular beam aperture and having at least one curved reflective surface which is parallel to the axis of said cylindrical light source and which extends through a series of points; the distance Ls of said reflective surface from the geometric axis of said cylindrical light source at the first (rearwardmost) point in said series being defined by the expression Ls R/arctan ((Js - Ks)/2) wherein R is the radius of said cylindrical light source, Js is the predetermined half-beam-width angle, and Ks is a selected angle which is less than a half-beam-width angle; the slope Ys of said reflective surface at said first point in said series being defined by the expression Ys (Js + Ks +2Xs)/4 wherein Xs is the polar coordinate angle of said first point Ps in said series as related to the geometric axis of said cylindrical light source and as measured from a center plane passed through the geometric axis of the light source and the center line of the illumination beam aperture of said reflector; the slope Yn of said reflective surface at every other point Pn in said series being defined by the expression Yn (Jn + Kn + 2Xn)/4 wherein Jn iS constant equal to the half-beam-width angle Js, Kn is an angle selected to have the characteristic Kn>Kn 1 >Ks, and Xn is the polar coordinate angle of the point Pn with Xn having the characteristic Xn Delta X + Xn 1; the distance Ln of said reflective surface from the geometric axis of said cylindrical light source at Pn being defined by the expression Ln Ln 1 (1 + sin Delta X tan (Xn 1 + ( Delta X/2) - Yn 1)).

Claim 9

An aircraft mounted ground illumination system for an optical lens system comprising: a plurality of illumination modules, each comprising a cylindrical light source and a trough-like reflector having a rectangular beam aperture and a pair of curved reflective surfaces parallel with the geometric axis of said cylindrical light source and formed to provide reflected light distribution weighted in a plane perpendicular to the geometric axis of said light source, at least a first one of said illumination modules being arranged with its axis parallel to a given direction so as to provide light distribution weighted in a plane perpendicular to said given direction, and at least a second one of said illumination modules being arranged with its axis perpendicular to said given direction so as to provide light distribution weighted in a plane parallel to said given direction, at least said first and second illumination modules illuminating in common at least a predetermined portion of a desired ground-imaged format additively in accordance with the expression I EgH2/Cos2 theta where I is radiant light intensity, Eg is ground irradiance compensated for the off-axis optical characteristic of the optical lens used, H is the aircraft altitude at which the optical lens is to be used, and theta is the slant range angle to said portion as measured from the nadir.

Claim 10

An aircraft mounted ground illumination system for an optical lens system comprising: a plurality of illumination modules, each comprising a cylindrical light source and a trough-like reflector having a rectangular beam aperture and a pair of curved reflective surfaces parallel with the geometric axis of said cylindrical light source and formed to provide reflected light distribution weighted in a plane perpendicular to the geometric axis of said light source, at least a first one of said illumination modules being arranged with its axis parallel to a given direction so as to provide light distribution weighted in a plane perpendicular to said given direction, and at least a second one of said illumination modules being arranged with its axis perpendicular to said given direction so as to provide light distribution weighted in a plane parallel to said given direction, at least said first and second illumination modules illuminating in common at least a predetermined portion of a desired ground-imaged format additively in accordance with the expression I EgH2/Cos2 theta where I is radiant light intensity, Eg is ground irradiance compensated for the off-axis optical characteristic of the optical lens used, H is the aircraft altitude at which the optical lens is to be used, and theta is the slant range angle to said portion as measured from the nadir.