Differential optical microscopy based on higher-order Gaussian-Hermite beam patterns.

A new method for performing scanning differential optical microscopy is described. This method is based on the use of a higher-order transverse mode of a laser. The technique is capable of responding to both amplitude and phase structures on the object. The sensitivity of the system in detecting differential object phase structures is similar to that of a dc scanning Nomarski microscope. The system is employed to image the surface structure of an integrated circuit.