COMPENSATION OF CHROMATIC ERRORS IN HIGH NA MOLDED OBJECTIVE LENSES

High NA molded glass objective lenses are commercially available for u se in the 680 nm to 850 nm range. We show that a simple positive lens can be used with an objective lens to compensate for wavelength-induce d aberration in the 400 nm to 700 nm range. There is a direct relation ship between the optimum power of the corrector lens and the wavelengt h of interest. We also show that a single positive lens and a holograp hic optical element can be used with an objective lens to compensate f or wavelength-induced aberration over a wide range of wavelengths.