Optical: systems and elements – Lens – With reflecting element
Patent
1997-04-07
1999-11-09
Epps, Georgia
Optical: systems and elements
Lens
With reflecting element
359625, 359592, 359595, 359596, G02B 1700
Patent
active
059825626
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention concerns optical elements for use as lenses, collimators and collectors of radiation. More particularly, it concerns lenses formed by arrays of reflecting slats, which are suitable for focusing, collimating, or collecting radiation.
BACKGROUND TO THE INVENTION
The specification of International patent application No PCT/AU93/00453 discloses a range of radiation control devices (including radiation deflectors, concentrators and lenses), each of which is formed by an array of substantially identical reflecting elements. In addition, it is noted in the specification of International patent application No PCT/AU93/00453 that an array of elongate reflectors can be used for one-dimensional focusing (line focusing) of radiation, and that two such arrays of reflectors, crossed at right angles, will form the equivalent of an array of reflecting channels, with each channel having a rectangular cross-section (which is a square cross-section when the reflectors of each array of parallel reflectors have the same spacing). Thus a two-dimensional focusing array or lens can be constructed using two arrays of reflector strips or slats.
One advantage possessed by optical devices formed by an array of reflecting slats--including the "90.degree. crossed-slats" lens referred to above--is that the surfaces of the elongate reflectors can be polished and examined for flaws before the arrays of reflectors are assembled to form the optical device. This feature, as also noted in the specification of International patent application No PCT/AU93/00453, permits the reflective surfaces of the slats to be coated in a manner which ensures that those surfaces are selectively reflective at predetermined wavelengths.
The present inventor has also shown that this type of 90.degree. crossed-slats lens has an additional advantage over the devices previously used to focus x-radiation (and other radiation having a wave-like character) onto a focal zone. The additional advantage is a significant increase in the "intensity gain" of the lens or focusing device. In this field, the gain, G. of a lens or focusing device is defined by the relationship: ##EQU1## where I.sub.d is the intensity of radiation in the focal spot or zone of the device and I.sub.o is the intensity of radiation at the same location in the absence of the focusing device.
DISCLOSURE OF THE PRESENT INVENTION
In further developmental work with slatted lenses and crossed-slats lenses, the present inventor has ascertained that improved slatted lenses with a focussing efficiency approaching 100% can be produced if the individual reflectors or slats of the lens are not essentially the same as each other, but the slats have a progressive change in surface area as the distance of the slats from the axis of the lens increases. The lenses are preferably produced such that, (i) the slats are planar, and (ii) the change in surface area of the slats with distance from the axis of the lens will be a decrease in surface area. However, in the manufacture of such lenses, the slats of a lens may conveniently be in groups of equal "front-to-back" length, t, but with varying spacing, d, between the slats in a group, such that the ratio of d.sub.n /t.sub.n is determined by the angle of incidence, on the nth slat of the lens, of radiation from a point source on the lens axis, .gamma..sub.n, as is approximately given by the relationship: ##EQU2## for a magnification of one, and, perhaps more precisely given by: ##EQU3## where d.sub.n is the separation (or spacing) between the nth and (n+1)th slats of the lens, t.sub.n is the extent of the nth slat in a direction parallel to the lens axis, and, M is the magnification of the lens.
Preferably, the separation of the slats of the lens (that is, the spacing--or average spacing--between adjacent slats of the lens) will be such that no slat or reflector creates a "shadow" on its adjacent outer reflector in the lens, from radiation from a point source at an expected point on the axis of the lens. This usually means that the s
REFERENCES:
patent: 1193999 (1916-08-01), Dixon
patent: 3322032 (1967-05-01), Leach
patent: 3425056 (1969-01-01), Dawson
patent: 3543024 (1970-11-01), Kantor
patent: 4022186 (1977-05-01), Northrup, Jr.
patent: 4312329 (1982-01-01), Carver et al.
patent: 5532884 (1996-07-01), Lee et al.
Epps Georgia
Schwartz Jordan M.
The Australian National University of Acton
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