The lens is the last link in the optical path of the laser projector
. The quality of the lens is good or not. Whether the aperture value f can be minimized is directly related to the brightness.
Generally speaking, the short-focus lens has a larger light loss than the telephoto lens. F is the clear rate of the lens. The larger the aperture f (the smaller the f-number), the greater the lens' transmittance.
The projection ratio is an important parameter of the projection lens. The projection ratio = projection distance / picture width. The projector lens can be divided into: ultra-short focus-short focus-conventional focal length-telephoto according to the projection ratio. A throw ratio of 0.5 or less is generally called ultra-short throw. A throw ratio of 0.5-1.0 is called short throw.
The conventional focal length projection ratio is generally 1-3, and the telephoto is generally more than 3.0. The projector lens can be divided into fixed focus lens and zoom lens according to whether the projection ratio is fixed or variable. For example, DHN Ultra Short Throw Laser Projector DM907
with a throw ratio of 0.25 is an ultra-short throw fixed focus lens. DHN Laser Projector DU6100
projection ratio 1.2-2.13 is a conventional zoom lens.
For different dimensions, there will be different classifications of the projector lens, for example, according to the material, there may be glass lens, resin lens and so on.