Cumming, Benjamin PDebbarma, SukhantaLuther-Davies, BarryGu, Min2015-12-100946-2171http://hdl.handle.net/1885/69330We demonstrate compensation for the spherical aberration due to the refractive index mismatch that occurs when a laser beam is focused into a thick arsenic trisulfide (As -2 S -3 ) film with a high numerical aperture objective. The effects of the aberration at different focal depths on the point spread function have been calculated numerically and the axial response method shown to be a useful measure for compensating the spherical aberration. We show that with the addition of adaptive optics based on a spatial light modulator, the aberration can be significantly reduced, resulting in an increase in peak intensity by a factor of 2.4 and a decrease in axial elongation by a factor of 2.2.Keywords: Axial elongation; Axial response; Focal depth; High numerical aperture objective; Peak intensity; Refractive index mismatch; Spatial light modulators; Spherical aberrations; Aberrations; Light modulators; Optical design; Optical transfer function; Arsenic201210.1007/s00340-012-5180-92016-02-24