Three-dimensional optical transfer functions of an optical heterodyne scanning microscope

Abstract

Optical scanning systems are broadly used in a variety of imaging schemes in microscopy. However, the image processing operations achievable with a scanning optical system are limited to those corresponding to a real and positive point spread function.1 An optical heterodyne laser scanning system has been introduced to overcome the constraints.2 Here, we investigate the defocusing imaging effect on the optical transfer function (OTF) of the optical heterodyne scanning system and discuss the synthesis of OTFs from defocused 2-D OTFs. Through analytical and simulation results, we show the synthesis of 3-D OTFs using two spatially separated scanning Gaussian laser beams as one example, and two superimposed Gaussian beams apodized by complementary Fresnel zone plates as another example. Low frequency de-emphasis of the obtainable 3-D OFTs is achieved.