Method of visualizing minute particles

DETAILED DESCRIPTION What is claimed is: 1.
A method of determining the geometric dimension of a minute particle disposed on the top surface of a substrate, comprising: generating a plurality of coincident light beams arranged in a row; directing said plurality of coincident light beams toward the substrate and the minute particle; viewing said plurality of coincident light beams as they are reflected from the minute particle and the substrate; determining the gray scale intensity levels of each of the beams reflecting from the minute particle and substrate; determining a weighted average gray scale value of the plurality of reflected beams; calculating the center of intensity of the beams reflecting from the minute particle and the substrate; and determining a weighted average dimension of the minute particle based on the calculated center of intensity.
2.
A method according to claim 1, wherein the step of directing said plurality of coincident light beams includes the steps of: directing a set of forward laser beams toward the surface of the substrate; directing the set of forward laser beams rearwardly downwardly at an angle .
theta.
.
sub.
ss relative to the horizontal plane of the substrate; projecting a set of rear laser beams toward the surface of the substrate; and directing the set of rear laser beams forwardly downwardly at an angle .
theta.
.
sub.
SR relative to the horizontal plane of the substrate.
3.
A method according to claim 2, wherein .
theta.
.
sub.
SS is between about 1 degree and about 89 degrees.
4.
A method according to claim 3, wherein .
theta.
.
sub.
SS is between about 15 degrees and about 75 degrees.
5.
A method according to claim 4, wherein .
theta.
.
sub.
SS is about 60 degrees.
6.
A method according to claim 2, wherein .
theta.
.
sub.
SS is between about 180 degrees and about 0 degrees.
7.
A method of determining the geometric dimensions of a minute particle according to claim 1, wherein the step of viewing includes: forming an image of said plurality of coincident light beams; splitting the image of said beams into a pair of images; reflecting said pair of images to form a group of image segments; and developing a pixel image voltage in response to viewing in a predetermined order each segment, wherein each voltage developed is indicative of the gray scale intensity level of the corresponding beam reflecting from the minute particles and substrate