Diffraction-limited gradient-index lenses with high numerical aperture for applications in laser beam-shaping and medicine

Diffraction-limited focusing lenses with a numerical aperture of 0.52 and diverging lenses with a numerical aperture of 0.62 were fabricated by silver-sodium ion exchange in cylindrical and rod geometry. The silver ion exchange in a sodium-aluminosilicate glass was optimized by the simulation of the diffusion equation for concentration-dependent diffusion coefficients and by direct measurement of the index profile by the refracted -near-field-method. The performance of the lenses was proved by interferometrical measurements of wavefront aberrations. Applications of gradient-index lenses to the fast-axis-collimation (FAC) of high-power lasef diodes and in endoscopic systems are discussed.