title = "Optical Comparators and Profile Projectors"

content = """
Optical comparators (profile projectors) are inspection instruments that project a magnified silhouette of a part onto a screen, allowing profile, form, and dimensional features to be compared against a template or measured directly using the screen's calibrated grid and digital readout. At Ridgecrest Metalworks, the optical comparator is used extensively for inspecting small machined parts, screw thread profiles, cutting tools, and complex profiles that are difficult to measure with contact instruments.

The instrument works by illuminating the part from below (transmitted light) or from the side (surface reflected light). Transmitted light produces a sharp shadow outline of the part profile on the screen. The screen has a calibrated graduated overlay or uses a digital protractor/scale read-out. Common magnification options are 10×, 20×, 50×, and 100×; higher magnification gives greater resolution for smaller features.

Applications of the optical comparator at Ridgecrest:
- Thread profile verification: Verifying the thread form angle (60° for metric/unified), pitch, and crest/root geometry using a transparent overlay chart for the specific thread standard
- Gear tooth profile check: Comparing the projected tooth form against a template or DXF overlay
- Radius and contour checking: Measuring blend radii, chamfer angles, and complex machined profiles using the screen's angular readout
- Small part first-off inspection: Rapidly verifying the profile of turned, milled, or ground components that would be slow to measure using hand tools
- Drill and cutter geometry: Checking point angle, relief angle, and edge condition of cutting tools

Overlays (Mylar charts) are drawn to scale matching the instrument magnification and the nominal part geometry. The projected shadow is overlaid on the chart; deviations from the nominal profile are visible as gaps or overlaps.

For quantitative measurement, the part stage is moved using precision lead screws with digital readouts (X and Y) or a rotary stage for angular measurement. Modern optical comparators include digital readouts with direct measurement of coordinates, diameters (by scanning across a feature), and angles.

Calibration of the comparator screen stage is performed using a certified glass scale or calibration standard. Lamp intensity and condenser alignment affect edge sharpness; these are checked and adjusted during periodic maintenance.
"""

version = "0.0.1"
