ULTRAHIGH-NUMERICAL-APERTURE IMAGING CONCENTRATOR

A monochromatic analysis of the RX nonimaging concentrators as imaging optical systems is presented (R stands for refractive, X for reflecti ve). All of them have rotational symmetry and an image-side numerical aperture of 1.46 with the use of an index of refraction n' = 1.5, whic h means a half-rim angle of illumination of 77 deg. This is equivalent to 95% of the theoretical limit of concentration. For an object-side focal length of f = 17.1 mm (i.e., an entry aperture diameter of 50 mm ) and a wavelength lambda = 950 nm, the RX has an equivalent passband above 32 mm(-1) in a field of view of +/-3.2 deg and above 19 mm(-1) i n a field of view of +/-4.8 deg. This feature of RX concentrators allo ws one to use the same RX with receivers/emitters very different from the one of the design presented (in size and contour shape) with no lo ss of nonimaging quality. Moreover, the combination of simplicity, com pactness, imaging capability, and high concentration makes the RX an e xceptionally good optical device for high-sensitivity focal plane arra y applications. (C) 1997 Optical Society of America.