High-NA achromatic objective lens

Developed an achromatic high-NA objective making use of non-periodic phase structures. The effectiveness of the achromatic objective lens has been demonstrated in the BD recorder. No reduction of the recording quality due to laser wavelength shift could be observed. Due to the wide nature of the zones, the phase structure can directly be incorporated into the aspherical surface of the objective lens without significantly influencing the transmission of the objective, making it a cost effective way to make the objective achromatic.