Optical Comparators

Optical comparator thread inspection

Picture above shows typical application of optical comparators – thread inspections. Optical comparator is made by Dorsey Metrology, model 16H with optional surface illumination (not switched on in photo) and precision fixture with 2.12″ jaw opening.

Before doing any work on electric parts of optical comparator make sure that power is off or power cord is disconnected.

Optical comparator profile lamp

To change the optical comparator lamp first use the two thumbscrews located on top of the lamp house to remove the lamp house cover. Remove the bulb by grasping and pulling the bulb directly up. Remove the new optical comparator replacement bulb from its box, and slide the new bulb in place. Switch main power on, remove the objective lens, and set lamp intensity to low. Verify that the lamp filament projected on the optical comparator screen is centered over the cross-hairs. Re-seat lamp and or adjust holder if required.

If the glass lamp is accidentally marked, remove the marks immediately by swabbing with methanol. The optical comparator profile lamp operates at a high temperature and any finger marks will be “burned” into the surface of the quartz reducing the output and life of the lamp.

Optical comparator surface illumination lamp

To change the surface illumination lamp first remove the lamp house cover.

To remove the bulb, grasp and rotate the bulb ejection wire to eject bulb. Remove the new replacement bulb from its box, flip the bulb ejector wire down and slide the new bulb in place. Switch main power on and set optical comparator surface illumination lamp intensity to low. Verify that the projected illumination is centered on the end of the fiber optic cable. Re-seat lamp and or adjust holder ( by bending face ) if required.

Same caution steps apply to optical comparator surface illumination lamp as to profile lamp.