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page 201

2.The Detector - a collimated light source is shone upon the pattern. The light is then reflected back to a grid of sensors. The sensors then go on/off to indicate the presence of the band.

on off on off

35.7.2.2 - Practice Problems

1.If Moire fringes are 1/4” in height and an array of 4 photocells are used to pickup the light patterns, how far apart would 50 micro in. wide lines have to be if the two patterns were at 45° angles?

2.Given that four measurements (x, y, z) were taken on a sphere, develop an expression to estimate a radius for the sphere, and an average error.

AM:35.7.3 Coordinate Measuring Machines (CMM)

Automated machines used for inspection of parts

Variety of methods for determining point locations in space,

-touch sensors,

-laser grids,

-video cameras

Advantages,

-can automate inspection process

-less prone to careless errors

-allows direct feedback into computer system

Disadvantages,

page 202

-costly

-fixturing is critical

-requires a very good tolerance model