Abstract: An optical system applied to an optical biometer is disclosed. The optical system includes a light source, first and second switchable reflectors, and first and second fixed reflectors. The first switchable reflector is disposed corresponding to the light source. The second switchable reflector is disposed corresponding to an eye. In a first mode, the first and second switchable reflectors are switched to a first state, and the incident light emitted by the light source is reflected by the first fixed reflector along a first optical path and then emitted to a first position of the eye. In a second mode, the first and second switchable reflectors are switched to a second state, and the incident light is sequentially reflected by the first switchable reflector, the second fixed reflector and the second switchable reflector along a second optical path and then emitted to a second position of the eye.

Abstract: An air filtration device for projector includes a holder, a filter, and a rack. The rack is movably disposed in the holder for supporting the filter. When the rack moves to a first position, the rack is received within the holder. When the rack moves from the first position to a second position, the filter is released from the rack for replacement.

Abstract: An air filtration device for projector includes a holder, a filter, and a rack. The rack is movably disposed in the holder for supporting the filter. When the rack moves to a first position, the rack is received within the holder. When the rack moves from the first position to a second position, the filter is released from the rack for replacement.