Läätsede

Läätsede is the Estonian term for lenses, optical elements that transmit and refract light to form images. By shaping curvature and choosing appropriate materials, lenses can converge or diverge light, affecting focal length and image sharpness. Lenses are used in everyday eyewear, cameras, microscopes, projectors, and many other instruments.

In ophthalmology, läätsed include spectacle lenses worn in glasses and contact lenses worn directly on the eye. Spectacle lenses correct refractive errors such as myopia, hyperopia, and astigmatism and may incorporate coatings for scratch resistance, reflection reduction, or UV protection. Contact lenses are available in soft and rigid gas-permeable forms and are selected by prescription.

In imaging and scientific instruments, lenses are designed as single elements or as complex assemblies (combinations of multiple lenses) to control focal length, field of view, distortion, and aberrations. Common types include convex (converging) and concave (diverging) lenses, as well as modern aspheric designs and zoom configurations. Materials range from traditional crown and flint glass to plastics like polycarbonate and high-index polymers, often with anti-reflective and scratch-resistant coatings.

Manufacture involves shaping, polishing, and coating glass or plastic elements, followed by precision assembly into lens housings. Quality control uses optical testing methods to measure focal length, transmission, and aberrations. The term läätsede thus covers a broad category of optical components central to vision, imaging, and measurement.