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Optical material selection

When choosing light-control materials, not only their optical properties should be considered, but also their adaptability, such as strength, durability, heat resistance, resistance to ultraviolet radiation, and ease of processing. Aluminum is the most commonly used specular reflective material. Because it is light, not fragile, and easy to shape, it has been used to replace silver-coated glass. Electrolytic polishing or mechanical polishing can give the surface of aluminum parts the best specular properties (it is the opposite of diffuse reflection and can form a clear image). High-purity aluminum has a higher reflectivity, but the material is softer. A compromise is to coat commercial-grade aluminum with a layer of high-purity aluminum. Although aluminized glass has a high reflectivity, it is rarely used to make lamps except for the aluminized surface of glass bulbs. Aluminized plastics coated with protective paint are suitable for making indoor lamps, but their processing methods seem to be less economical. Although chrome plates and stainless steel have good specular reflection, they have low reflectivity and are not suitable for Reflectors.

White paint on metal surfaces can produce diffuse reflection. In order to facilitate cleaning, the paint surface is usually required to have a glossy finish, but the specular reflection caused by the gloss has no practical significance in the optical design of the lamp.

Glass is suitable for use as a refractive material where heat resistance is required. Polymethacrylate (i.e. acrylic plastic) can be widely used as a refractive prism on indoor and outdoor lamps. Polystyrene is cheaper than acrylic plastic, but it is not suitable for outdoor use. Polyvinyl chloride (PVC) has good impact resistance and can be used outdoors, but its cost is higher than acrylic plastic. When high impact strength is required (such as for street lamps to prevent intentional damage), polycarbonate or cellulose acetate-butyrate can be used. Although they have the disadvantage of low transmittance, they are desirable from the perspective of light stability.

Acrylic, polyvinyl chloride, polystyrene and glass all have milky white varieties, which are suitable for shielding light sources or making Reflectors with uniform brightness.