Wilson, T., Juskaitis, R., Neil, M. A. A. and Kozubek, M.
Confocal microscopy by aperture correlation. Optics Letters 21: 1879-1881 (1996).

Most confocal microscopes do not produce images in real time with nonlaser light sources. The tandem scanning confocal microscope does produce such images but, because the pinhole apertures of the Nipkov disk must be placed far apart to reduce cross talk between neighboring pinholes, only 1% or less of the light available for imaging is used. We show that, by using aperture correlation techniques and relaxing the requirement to obtain a pure confocal image directly, one can obtain real-time confocal images with a dramatically increased (25% or even 50%) light budget.