[OPTICAL REVIEW Vol. 8, No. 4 (2001) 284-286]

Halo Reduction Technique in Phase Contrast Microscopy

Tatsuro OTAKI*

Optical Design Department, Instruments Company, Nikon Corporation, 1-6-3, Nishi-Oi, Shinagawa-ku, Tokyo, 140-8601 Japan

(Received February 1, 2001; Accepted April 26, 2001)

A new phase contrast microscopy technique has been developed which achieves halo reduction by applying an apodization to the Zernike phase contrast method. In this technique, a new apodized phase plate is placed at the back focal plane of the objective. This plate consists of a quarter wave phase shift ring conjugated of the illuminating aperture, which has a 25% transmittance, and a pair of adjacent rings having 50% transmittance. The developed technique yields the highest resolution images without a bluish hue effect ever achieved in phase contrast microscopy.

Key words : phase contrast microscopy, apodization, halo, phase difference, bluish hue, apodized phase contrast