US 4,728,196 AGranted

Arrangement for determining a surface structure, especially for roughness

AssigneeOptische Werke G. Rodenstock

InventorOskar Gerstorfer

Life of this patent

Estimating the term…

Loading patent…

Abstract

An arrangement for determining the surface structure and especially the roughness of a specimen which includes an image lens system that focuses a parallel ray onto the surface to be examined with an inclined incidence direction and a lens system which reproduces the reflected light beam on a detector array. The distance of the detector array is approximately equal to the focal distance of the lens system. The distance of the surface from the lens systems is also approximately equal to the focal distance of the lens systems. The arrangement according to the invention offers the advantage that also with an areal specimen illumination as well as with greater changes of the distance between the arrangement and the surface to be examined, an unequivocal coordination exists between the angle, under which the light is reflected, and the individual detector elements.

Claims23

Dependent claims

An arrangement for determining at least a surface structure of a specimen in which angular dependence of radiant energy reflected from said surface structure for angles about a reflection angle of an ideal surface is measured, comprising

a detector array means comprised of a plurality of individual detectors sensing radiant energy received from said surface structure for producing output signals,
first lens means
having a focal distance and whose distance from said surface structure of the specimen is approximately equal to said focal distance of said first lens means
for focusing a substantially parallel radiant energy beam received from a radiant energy source onto said specimen in such a manner that an axis of the said focussed light beam subtends an angle not equal to zero with respect to a line substantially perpendicular to said surface structure of the specimen,
second lens means receiving radiant energy at multiple angles of reflection from said surface structure and having a focal distance substantially equal to the distance between said second lens means and said detector array means and, for plural angles of said multiple angles of reflection imaging at a predetermined location on the radiant energy detector array means radiant energy reflected from said surface structure at a given angle of reflection, and
an evaluator circuit responsive to said output signals from said individual detectors for calculating measurement elements for roughness of the surface structure.

3 more elements

Apparatus for determining a surface structure of a surface comprising

a radiant energy source means for transmitting parallel rays of energy,
a lens means having a first focal distance facing said surface structure and focussing said transmitted energy on said surface structure, an axis of said focussed energy being at an angle not equal to zero with respect to a line substantially perpendicular to said surface structure,
a radiant energy detector array means organized of a plurality of individual detectors for receiving radiant energy reflected at plural angles of reflection to image energy reflected from said surface structure for a given angle of reflection at substantially a same location on said radiant energy detector array means for producing output signals,
means for projecting the radiant energy reflected from the surface structure of a given angle of deflection onto a predetermined location of the radiant energy detector array substantially independent of the distance of the surface, and
an evaluator circuit resposive to said output signals from said individual detectors for calculating measurement elements for roughness of the surface structure.

2 more elements

Dependencies are inferred from the claim text.