Profile Projector

Overview

A profile projector is a benchtop optical comparator built for shop-floor and quality-lab inspection of small precision parts. It magnifies the outline of a part onto a large frosted screen, where features can be checked against a chart, and it adds a measuring stage and electronic readout so dimensions and angles can be captured as numbers rather than judged by eye. A built-in edge detector lets it find feature edges automatically, removing the operator guesswork of lining up a cross-hair.

The Projection System casts the magnified, erected image onto a ground-glass screen using profile and surface lamps and a chain of folding mirrors. The part rides on the Measuring Stage, a rotary table on a motorized X-Y cross-slide with an encoder on every axis. The Digital Readout counts those encoders, runs a CCD edge sensor, and computes geometry on a touchscreen. The optics and stage sit on a rigid cast Base.

How it works

For contour inspection the Projection System back-lights the part with a halogen profile lamp through a telecentric condenser, so the projected silhouette stays true to size no matter where the part sits in the beam. A projection objective from the interchangeable set sets the magnification, folding mirrors fit the long path into the cabinet, and the erected image lands on the rotatable screen with its etched cross-hairs and protractor. For opaque surface detail a separate surface lamp lights the part's front face.

To measure, the operator drives the Measuring Stage with its ball-screw axes while linear glass-scale encoders track travel and a rotary encoder tracks the table angle. Rather than manually aligning each edge to a cross-hair, the Digital Readout uses its CCD edge detector: a small sensor window watches the screen and the electronics register the exact instant a high-contrast edge crosses it, so positions are captured repeatably.

The processing module then turns captured points into geometry, fitting lines, circles, and angles, and reports distances, diameters, and form errors. All of this depends on a stable structure, which is why the Base is a heavy ribbed casting on leveling feet that isolates the long optical path from bench vibration.