Restriction Zone (RZ) based on the HD

The projector is also suitable for rear projection applications; projecting a beam onto a defuse coated projection screen. As displayed in following graphic, two areas should be considered: the restricted enclosed projection area (RA) and the observation area (VE).

For this type of setup 3 different HD shall be considered:

• HD as discussed in “High Brightness precautions: Hazard Distance”, relevant for intrabeam exposure.
• HD_reflection : the distance that has to be kept restrictive related to the reflected light from the rear projection screen.
• HD_diffuse : the relevant distance to be considered while observing the diffuse surface of the rear projection screen.

As described in “High Brightness precautions: Hazard Distance”, it is mandatory to create a restricted zone within the beam areas closer than any HD. In the enclosed projection area the combination of two restricted zones are relevant: The restricted zone of the projected beam toward the screen; taking into account 1 meter Separation Width (SW) from the beam onward. Combined with the restricted zone related to the rear reflection from the screen (HD_reflection); also taking into account a 1 meter lateral separation.

The HD_reflection distance equals 25% of the difference between the determined HD distance and the projection distance to the rear projection screen. To determine the HD distance for the used lens and projector model see chapter “HD in function of modifying optics”.

HDreflection = 25% (HD – PD)

The light emitted from the screen within the observation shall never exceed the RG2 exposure limit, determined at 10 cm. The HD_diffuse can be neglected if the measured light at the screen surface is below 5000 cd/m² or 15000 LUX.