AMBIENT LIGHT REJECTING SCREENS EXPLAINED

Ambient Light Rejecting (ALR) screens differ from a regular screens in several ways.

The most common screen surfaces reflect the incoming light uniformly in all directions.

These screen surfaces are referred to as diffuse reflectors. The light is reflected back in many angles, rather than just at one angle. Surfaces that reflect back at only one angle are referred to specular reflectors - they reflect light at an angle precisely opposite the one at which that light arrived, such as a mirror.

Some projector screens may not be purely diffuse reflectors in the sense that they may reflect light back in one direction more than other directions. This is often done to increase the brightness of the reflected image (gain) within a certain area (viewing angle).

An ALR screen works by selectively reflecting light back to the audience. This effect is achieved by positioning the projector and screen in such a way that the projector's light is bounced towards the audience, while the other light in the room is reflected back in some other direction.

Some ALR screens work due to a principal referred to as Angular Reflectivity. This means that your projected image will reflect back to the audience at the mirror-opposite angle to the projector hitting the screen. I.e. if the projector is angled down at a 15 degree angle, the audience will get the brightest image while viewing the screen looking up at 15 degrees.

 

 

Other ALR (Ambient Light Rejecting) screens counteract ambient light through the use of optics. Optical ALR screens typically consist of multiple layers, each with distinct absorption and reflectivity properties, often incorporating lens-like elements. This structure is known as a lenticular design.

Regardless of the ALR technology your screen employs, some ambient light will still penetrate. ALR screens are only effective if the ambient light does not come from the same direction as the projector. For example, if your projector is placed at the back of the room near other light sources aimed at the screen, the ALR surface won't mitigate that lighting.

To benefit from an ALR screen, the ambient light source must come from a different direction or angle than your projector. This includes light reflecting off white walls, overhead or recessed lighting, or windows on the side of the room.