AUTHORS: R. V. Dantu, Nikitas J. Dimopoulos, R. V. Patel 
	 and A. J. Al-Khalili
	 
TITLE:   Depth Perception Using Blurring and its Application 
	 in VLSI Wafer Probing
	 
IN: 	 Machine Vision and Applications, Vol. 5, 
	 May, 1992, pp. 35-45 


ABSTRACT

In this paper, we present a technique for measuring the amount of blur 
of an edge and using this information to determine the distance of a 
micromanipulator probe from a wafer surface in very large scale 
integration (VLSI) wafer probing.In this application, a soft and 
reliable touch of the probe with while approaching the wafer are 
analyzed. In our theory, the amount of blur is calculated from the 
height of the step edge and the slope of the intensity profile at the 
zero crossing. Hence, our formula is simple and easy to use. We estimate 
the distance of the probe from the surface of the wafer and obtain a 
robust measure, i.e., one which is valid even in the presence of 
significant noise in the images. In order to validate our methods, 
we have experimented with various VLSI patterns as background.