Hazard Distance For Fully Closed Projection System - Barco F70 Series User Manual

1.5 Hazard Distance for fully closed projection
system
HD
Hazard Distance (HD) is the distance measured from the projection lens at which the intensity or the
energy per surface unit becomes lower than the applicable exposure limit on the cornea or on the
skin. The light beam is considered (to be) unsafe for exposure if the distance from a person to the
light source is less than the HD.
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 image 1-3 two areas should be considered: the restricted enclosed
projection area (RA) and the observation area (TH).
RESTRICTED
AREA
Image 1–3
RA Restricted Access location (Enclosed projection area)
PR Projector.
TH Theater (observation area).
Restriction zone (RZ) based on the HD continued.
For this type of setup 3 different HD shall be considered:
• HD as discussed in "High Brightness precautions: Hazard Distance (HD)", page 6 , relevant for intrabeam
exposure.
• HDreflection : the distance that has to be kept restrictive related to the reflected light from the rear
projection screen.
• HDdiffuse : the relevant distance to be considered while observing the defuse surface of the rear projection
screen.
As described in "High Brightness precautions: Hazard Distance (HD)", page 6 , it is mandatory to create a
restricted zone within the beam areas closer than any NOHD. 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 (HDreflection); also taking into account a 1 meter lateral separation.
The HDreflection 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 graphs in chapter "HD in function of the lens Throw Ratio (TR)", page 8 .
HDreflection = 25% (HD – PD)
RA
RZ
PR
RZ
PD
SW
TH
HD
DIFFUSE
PD
HD
REFLECTION
Restriction Zone
Projection Distan
Separation Width. Must be minimum 1 meter.
601–426 /15
Safety
F70 Series 19