Lenses of different materials will have different effects on the picture. According to the projector lens on the market at present, their lenses are mainly divided into two types, one is glass lens, the other is resin (also known as plastic) lens.
1. Glass Lens
(1) Good heat resistance.
(2) Glass lens is made by single grinding, with good processability and high precision.
2. Resin Lens
(1) Compared with glass lens, its heat resistance is insufficient, and deformation will occur at high temperature.
(2) Resin lens is manufactured by precision injection molding with abrasive tools, and its surface precision reaches micron level. However, it requires high processing environment and other conditions, and its processing performance is not stable compared with glass lens.
In terms of physical properties, glass is generally superior to resin. But some high-order resin lenses are comparable to glass lenses. In addition to pure resin lens group and pure glass lens group, there are often lens sets with complementary lenses of two materials.
A large amount of manpower and time are consumed in the grinding process of glass lens, which leads to the slow improvement of productivity and yield. While resin lens is attractive for products with low performance requirements and price orientation because of the low melting point of the resin, it is easy to form, mass manufacture and the cost is easy to control. This is also the reason why resin lenses are used in most low lumen micro projectors on the market.
Because of the special requirements for light, the glass lens used in the projector will be mixed with special compounds and metals into ordinary glass to make the required optical glass. Optical glass can change the direction of light propagation and the relative spectral distribution of ultraviolet, visible or infrared light, so as to meet the requirements of projector optical system. In addition, the glass itself has heat resistance and light transmittance, which makes it naturally become the best material for projector lens.