A professional who tends electric oven-type machine that hardens lenses used in safety eyeglasses, and tests hardness of lens, using steel-ball drop-test. Respnsibilities include:

• Measures lens thickness with calipers to determine if lens meets thickness requirements for prescribed hardening.
• Positions lenses in holding fixture and pushes fixture into electric oven.
• Sets timer and temperature controls on oven according to chart specifications for prescribed hardness of lens.
• Removes lenses at end of cooling cycle, or places lenses in airflow to cool.
• Holds finished lens in polarized light fixture to detect defects produced by hardening.
• Places lens on bed of drop-test fixture and covers lens with cloth or plastic.
• Places steel ball of specified weight in release mechanism of fixture.
• Positions mechanism at specified distance from lens and releases ball.
• Discards broken lenses.