Lensmaking

Lensmaking is the fabrication of optical lenses from materials such as glass or clear plastics to achieve specific refractive properties. It covers design, shaping, grinding, polishing, coating, and testing, and is applied to single lenses and complex assemblies used in eyeglasses, cameras, microscopes, telescopes, and other optical instruments.

Materials commonly used include crown and flint glass, fused silica, and optical polymers such as PMMA and polycarbonate. Lens designs consider curvature, thickness, refractive index, dispersion, and aberration correction. Modern lenses may be aspheric, gradient-index, or arranged as multi-element assemblies such as achromats or apochromats.

Manufacturing typically begins with selecting a suitable blank, followed by rough grinding to approximate curvature, fine grinding and lapping to improve surface accuracy, and polishing to a smooth optical finish. Edges are beveled and apertures prepared. Surfaces may then be coated with anti-reflective, hard, or protective coatings, and the elements aligned for assembly. Final testing verifies focal length, surface quality, and tolerances.

Quality control employs metrology such as interferometry, profilometry, and refractometry, with standards for surface roughness and scratch-dig. The lensmaking industry has evolved from manual, craft-based techniques to computer-controlled grinding, precision polishing, and automated coating processes, enabling mass production as well as custom, high-precision optics.