Near-field tailored imaging optics for coupling ultra-bright light sources into optical fibers

We explore compact, imaging (aplanatic) designs capable of reconstituting the power density of ultra-bright lamps at a remote target, with specific application to optical fiber light transport. The solutions presented here, for concentrating incoherent light from an extended near-field source, closely approach the thermodynamic limit for optical performance at high collection efficiency, as confirmed with raytrace simulations. Our investigations are motivated by the prospect of arc-discharge lamps as effective alternatives to lasers for many surgical procedures where high intensity heating rather than monochromaticity is needed. Additional applications include LED-fiber and fiber-fiber coupling, as well as projection systems. Consideration is restricted to pure reflective (mirrored) systems since refractive elements can introduce inadmissibly large chromatic aberrations. The tailored aplanatic mirror contours constitute monotonic functions that can be solved analytically, which facilitates rapid surveying of a wide range of design options. Several near-field designs suitable for coupling high numerical aperture light sources into optical fibers are presented.