line safety

Hello everybody,
I've been reading for a while on this forum, and have learnt alot.
I've found one old existing thread on this topic, but I'd like to start a new one.


I want to use a laser line (like the ones used on woodsaws), but alot brighter.
Since the laser line will have a chance of shining in peoples eyes for brief periods of time, i'm interested in safety...

Basically I want to know if this theory of mine is correct:
- The maximum power of a laser spot is 5mW to stay safe.
- The diameter of a pupil is 4mm (conservatively)
- The angle of my laser line will be about 30°

So according to my calculations the minimum distance one can hold his/her eye from the laser source is the following:

P laser [mW] MIN Line width [mm] MIN Distance [mm]
25 20 37,32050808
30 24 44,78460969
35 28 52,24871131
40 32 59,71281292
45 36 67,17691454
50 40 74,64101615
55 44 82,10511777
60 48 89,56921938
65 52 97,033321
70 56 104,4974226
75 60 111,9615242
80 64 119,4256258
85 68 126,8897275
90 72 134,3538291
95 76 141,8179307
100 80 149,2820323
105 84 156,7461339
110 88 164,2102355
115 92 171,6743371
120 96 179,1384388
125 100 186,6025404
130 104 194,066642
135 108 201,5307436
140 112 208,9948452
145 116 216,4589468
150 120 223,9230485
155 124 231,3871501
160 128 238,8512517
165 132 246,3153533
170 136 253,7794549
175 140 261,2435565
180 144 268,7076581
185 148 276,1717598
190 152 283,6358614
195 156 291,099963
200 160 298,5640646

I calculated these values with the following formulas:
Minimum width = (P/5mW)*4mm
Minimum distance = (Minimum width/2)/(tan(30°/2))


So, do you think this is correct?
Thanks

In other words, is it OK to assume that the power of a laser will be spread over the line? Making it relatively safe, as long as you stay further away than the "minimum distance" I calculated above.

Thanks

If my question or calculations aren't clear, please ask.
This is quite an important issue, it is safety... I'd like some advice please.

Thanks