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SYSTEM AND METHOD FOR GENERATING A TOPOGRAPHY MAP

IP.com Disclosure Number: IPCOM000008493D
Publication Date: 2002-Jun-18

Publishing Venue

The IP.com Prior Art Database

Related People

Andrei BRUNFELD: INVENTOR [+5]

Abstract

Apparatus for inspecting object including a scanner scanning a spot of illumination across a surface to be inspected, an optical system receiving a reflection of the spot and projecting it onto an array of sensors, and a height calculator calculating a height of the surface for a multiplicity of locations on the object, each calculation functionally related to a position of the spot on said array.

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[663.V250701]

System and Method for Generating a Topography Map

ABSTRACT
[0001] Apparatus for inspecting object including a scanner scanning a spot of illumination across a surface to be inspected, an optical system receiving a reflection of the spot and projecting it onto an array of sensors, and a height calculator calculating a height of the surface for a multiplicity of locations on the object, each calculation functionally related to a position of the spot on said array.

FIELD OF INVENTION
[0002] The present invention generally relates to apparatus and methods for generating a topography map of a surface, and more particularly to optical systems employed to generate topography maps used in surface inspection applications.

BACKGROUND OF THE INVENTION
[0003] It is well known to measure distances using optical apparatus. A typical application of optical distance measurement apparatus is to systematically acquire distance measurements and to construct a topographical map of a surface from the measurements. Such maps are used, for example, in the inspection of assembled or unassembled printed circuit boards, flat panel displays, ball grid array substrates and similar surfaces. Other uses optical distance measurement include non-contact profiling the shape of automobile car bodies and other automotive parts, surface digitization in modeling of medals, sculptures, automotive bodies, quality inspection, dimensional metrology and other suitable applications.
[0004] Some conventional height profiling and mapping systems employ one- dimensional or two-dimensional digital sensor arrays, for example CCD and CMOS sensors. A point or a linear portion of a surface is illuminated, and a height profile is

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calculated, typically by means of triangulation, as a function of which sensor elements are impinged upon by a reflection of the illumination off the surface being profiled. A full map of the surfaceis generated by acquiring a succession of profiles, for example by scanning the illuminated portion over the entire surface. Conventional systems suffer from one or more of the following drawbacks: inadequate resolution; limited size of the area that can be mapped; and limited speed at which the topography of a surface can be mapped.

SUMMARY OF THE INVENTION
[0005] The present invention seeks to provide improved high-speed apparatus for generating a high-resolution topographical map of a surface, particularly a topographical map that is suitable for inspecting surfaces for the presence of defects and for dimensional metrology.
[0006] In accordance with a general aspect of the invention there is provided a scanner scanning a spot of illumination across a surface to be inspected, an optical system receiving a reflection of the spot and projecting it onto a sensor, and a height calculator calculating a height of the surface at a multiplicity of locations thereon, as a function of a position of the spot on the sensor.
[0007] In accorda...