alr: Explained: What is an ALR projector screen and why do you need it

Ambient Light Rejection or ALR screens are gradually becoming popular as projector owners want to enjoy the best home theatre experience. ALR screens help in improving image quality in unfavourable theatre environments (especially in rooms that have multiple unwanted lights), however, they are way more expensive compared to the normal projector screens. ALR screens can cost you four times more than the regular white screens. Here we will discuss the importance of ALR screens.
Drawbacks of a regular white screen
Projectors function exactly in the opposite way that a TV does. Unlike TVs, projectors bounce light off a surface (usually a screen) rather than beaming light directly into the user’s eyes. However, the problem here is with the screen as a regular one not only reflects the light from the projector but also every other light present in the room.
Ambient light tends to reflect off of a white screen to create glares and wash out the projector’s image unless it is viewed in a pitch-black room (like the theatres). Moreover, ambient light is not only a daytime problem as the light from a projector can scatter and bounce off of lightly-coloured walls to create ambient light even in an otherwise dark room.
Ambient light usually poses a problem for most first-time projector owners. Most users are unable to solve the ambient light problem with proper research and even after spending a lot on heavy curtains. This is because some rooms (especially living rooms) are just not well-suited for projectors.
Importance of ALR projector screens
ALR projector screens can come in handy if a user is unable to properly black out a room. These screens reduce the impact of ambient lighting and provide its users with a better image quality during the daytime or in rooms with white walls.
How does Ambient Light Rejection work?
Unlike regular projector screens, ambient light rejection screens reflect the light in a single direction. Regular screens reflect light in every possible direction, whereas an ALR screen selectively reflects light only toward the audience. This helps the screen to offer a brighter and crispier picture without glare or washout by eliminating the negative effects of ambient light.
The technology that helps in ambient light reduction is a bit complicated and every manufacturer has different ways to imbibe the technology. On a basic level, ALR screens are made up of multiple tiny micro-structures and layered optical filters. These layers help the screen to reflect light in the desired direction.
To make it easier, we need to consider just two directions in which a screen reflects light — toward the audience and away from the audience. In the case of ALR screens, the light hits the screen and mostly reflects back at the viewers. However, when light hits an ALR screen at an odd angle to create ambient light, it is directed away from the viewers to cancel out any ambient light on the screen.
Types of ALR projector screens
Several types of ALR projector screens are available in the market. Here we will discuss the types of ALR projector screens that are available.
Angular-Reflective ALR screens
These screens reflect the projector’s image at the opposite angle of incidence, For example, if a ceiling-mounted projector is placed at a 5-degree angle, the image will reflect toward viewers off of the screen at the same angle.
Retro-Reflective ALR screens
The retro-reflective ALR screens offer users a higher image quality by reflecting projected light at the projector. However, these screens require precise installation for getting the best results.
Ceiling Light Rejection ALR screens
This screen technology also rejects ambient light. However, as the name suggests this type of ALR screen is best for negating light from ceiling fixtures.
ALR screens for ultra-short-throw projectors
ALR screens are very important for users who own ultra-short-throw projectors. These projectors reflect light at an extreme angle and usually don’t work with other types of ALR screens. Buyers should make sure that the ALR screen is compatible with their ultra-short-throw projector before purchasing.
Things to consider before buying an ALR projector screen
It is important to note that the precision offered by ALR projector screens comes at a cost. ALR screens can improve the image quality, however, they may reduce the viewing angles. Most new ALR screens offer a viewing angle of around 160 degrees which is good enough. But, some screens still offer only 90 degrees of viewing angle which can turn out to be an issue for wide rooms. Consumers should check the viewing angles before deciding upon a new ALR screen.