We analyze an optical system after inserting a simple quartic phase plate in its pupil plane to extend the focal depth. The system is used specifically to track distant objects like stars. We design an optimum quartic phase plate for a real lens system which has an effective focal length of 29 mm, an F-number of 1.6, a field of view of 20 degrees, and a working wavelength range of 0.5~0.75 µm. By introducing the quartic phase plate, we enhance the focal depth of the system more than threefold as compared to a system having no phase plate.
© 2003 Optical Society of America
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