Apparatus and method for optically measuring a surface
AssigneeMaterials Technologies Corporation
InventorJohn N. Pike
Life of this patent
Estimating the term…
Abstract
An apparatus and method measures the roughness or some other surface dimension by transmitting a beam of light through a grating member at an angle of incidence relative to the grating member. The grating member has a plurality of parallel opaque bars and adjacent transparent bars. The beam of light forms a multiple line shadow pattern on the surface below the grating member formed by the shadows of the opaque bars of the grating member. A camera records the multiple line shadow pattern, and the recorded pattern is superimposed on a plurality of parallel, equally spaced scan lines oriented perpendicular to the shadow lines. The distances between the points at which adjacent shadow lines cross each respective scan line are measured to determine the roughness or some other surface dimension.
Claims30
An apparatus for measuring the roughness of a surface, comprising:
- a grating member including a plurality of parallel substantially opaque portions and adjacent substantially transparent portions;
- a light source for transmitting a beam of light through the grating member at an angle of incidence relative to the grating member, the beam of light forming a multiple line shadow pattern on the surface adjacent to the grating member comprising the shadows of the opaque portions of the grating member;
- means for separating an image of the grating member from an image of the multiple line shadow pattern;
- and
- means for recording the separated image of the multiple line shadow pattern exclusive of the image of the grating member for measuring a plurality of distances between the adjacent lines of the pattern and determining the roughness of the surface based on the measured distances.
A method for measuring the roughness of a surface, comprising the following steps:
- transmitting a beam of light through a grating member located adjacent to the surface, the grating member including a plurality of parallel substantially opaque portions and adjacent substantially transparent portions, the angle of incidence of the beam of light relative to the grating member being selected to project a multiple line shadow pattern on the surface adjacent to the grating member formed by the shadows of the opaque portions of the grating member;
- separating an image of the multiple line shadow pattern from an image of the grating member;
- recording the separated image of the multiple line shadow pattern exclusive of the image of the grating member;
- and
- measuring a plurality of distances between the adjacent lines of the multiple line shadow pattern and determining the roughness of the surface based on the measured distances.
An apparatus for measuring at least one surface dimension, comprising:
- a grating including a plurality of substantially opaque portions and adjacent substantially transparent portions;
- a light source for transmitting a beam of light through the grating at an angle of incidence relative to the grating for forming a multiple line shadow pattern on the surface formed by the shadows of the opaque portions of the grating;
- a lens for separating an image of the multiple line shadow pattern from an image of the grating;
- and
- a recording unit for recording the separated image of the multiple line shadow pattern exclusive of the image of the grating for measuring a plurality of distances between the adjacent lines of the pattern and determining at least one dimension of the surface based on the measured distances.
An apparatus for measuring at least one surface dimension, comprising:
- a grating including a plurality of substantially opaque portions and substantially transparent portions between substantially opaque portions;
- means for transmitting light through the grating and forming a multiple line shadow pattern on the surface adjacent to the grating comprising the shadows of the opaque portions of the grating;
- means for transmitting an image of the multiple line shadow pattern into a focal plane separate from a focal plane of an image of the grating;
- and
- means for recording the image of the multiple line shadow pattern exclusive of the image of the grating to measure a plurality of distances between the adjacent lines of the pattern and determine at least one dimension of the surface based on the measured distance.
Dependencies are inferred from the claim text.