A user on this forum "stafil" has started a couple of topics in regards to eye safety with iPhone X and the new XS and XS MAX phones. He asked if somebody could measure what is really going on, so here goes.
We used a device to measure the power with which the two infrared sources are emitting. Unfortunately there were other light sources in the room so it was difficult to get really exact measurements. Still we repeated the measurements a couple of times and they were consistent to about 0.05 mW.
Additionally we also analysed how the sequence looks like in terms of pulse durations. Dot projector appears to work with about 5ms pulses.
There appear to be three distinct sequences.
1. Upon waking, the phone is using the flood illuminator to check for surroundings, most probably looking for a face to identify. A this point the flood illuminator is emitting about 0.2 mW of power.
2. When the IR camera detects a face, dot projector (short flash on the right side) emits a much more powerful beam. It doesn't look like it from the video, but we measured it to about 1.5 mW. Still this is just a single shot and if successful, the phone unlocks.
3. During normal operation flood illuminator fires up every couple of seconds, most probably to check if the user is looking at the screen. The power stays the same, about 0.2 mW.
From eye safety standpoint it is still difficult for me to comment. Before I dismissed these concerns as utterly irrelevant and paranoid. Now I'm leaning more towards "most probably OK for normal use, but don't put your phone next to your eye". Flood projector is most probably completely safe, because it is just an infrared flashlight. Yet the dot projector is actually quite focused and apparently ten times more powerful.
I still believe Apple did quite some testing and deemed the dot projector perfectly safe. Yet in a way it conforms to class 2 laser standard, if we speculate our measurements were on the high side (class 2 is limited to 1mW). Dot projector being near infrared also makes it a bit more dangerous, because there is no blink reflex.
https://en.wikipedia.org/wiki/Laser_safety#Class_2
Additionally dot projector is seldom activated, it is always at a considerable distance from the eye and it is dispersed into numerous small dots, from which most probably only one or two hit the eye.
We used a device to measure the power with which the two infrared sources are emitting. Unfortunately there were other light sources in the room so it was difficult to get really exact measurements. Still we repeated the measurements a couple of times and they were consistent to about 0.05 mW.
Additionally we also analysed how the sequence looks like in terms of pulse durations. Dot projector appears to work with about 5ms pulses.
There appear to be three distinct sequences.
1. Upon waking, the phone is using the flood illuminator to check for surroundings, most probably looking for a face to identify. A this point the flood illuminator is emitting about 0.2 mW of power.
2. When the IR camera detects a face, dot projector (short flash on the right side) emits a much more powerful beam. It doesn't look like it from the video, but we measured it to about 1.5 mW. Still this is just a single shot and if successful, the phone unlocks.
3. During normal operation flood illuminator fires up every couple of seconds, most probably to check if the user is looking at the screen. The power stays the same, about 0.2 mW.
From eye safety standpoint it is still difficult for me to comment. Before I dismissed these concerns as utterly irrelevant and paranoid. Now I'm leaning more towards "most probably OK for normal use, but don't put your phone next to your eye". Flood projector is most probably completely safe, because it is just an infrared flashlight. Yet the dot projector is actually quite focused and apparently ten times more powerful.
I still believe Apple did quite some testing and deemed the dot projector perfectly safe. Yet in a way it conforms to class 2 laser standard, if we speculate our measurements were on the high side (class 2 is limited to 1mW). Dot projector being near infrared also makes it a bit more dangerous, because there is no blink reflex.
https://en.wikipedia.org/wiki/Laser_safety#Class_2
Additionally dot projector is seldom activated, it is always at a considerable distance from the eye and it is dispersed into numerous small dots, from which most probably only one or two hit the eye.
