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03012011, 09:11 PM  #1  
 
Class 1 Laser Join Date: Sep 2010 Location: Athens, Greece
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Laser Divergence Calculator Example of an almost accurate aligned laser. A 473nm 50mw laser.. Divergence: 1.2mrad Hope you liked my project... __________________________________________________ _________________ Warning: VERY BAD ENGLISH... Last edited by Fivos; 03012011 at 09:14 PM.  
03012011, 09:49 PM  #2  
 
Class 4 Laser Join Date: Sep 2007 Location: Wisconsin
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I like working with ones better. Here's something a little more simple. If a laser diverges 1mm in 1m, the tangent of the angle would be equal to 1/1000: tan θ = 1/1000 θ = arctan(0.001) θ = 0.0009999 = 0.001rad = 1mrad Follow the steps backward to see that 2mrad just means it diverges 2mm for every meter.
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03012011, 10:34 PM  #3  
 
Class 3R Laser Join Date: Jul 2010 Location: Olomouc, Czech Republic
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Doing arctan of angles bellow 1 degree is redundant. It results in almost the same number.
 
03012011, 11:15 PM  #4  
 
Class 3B Laser  Quote:
I am probably the worst person at math here but if the numbers are "almost" the same, how is it redundant? i'm not being a smart ass. just looking for an explanation.
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03022011, 12:35 AM  #5  
 
Class 3R Laser Join Date: Jul 2010 Location: Olomouc, Czech Republic
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So if you make one measurement of beam diameter at large distance, all you need for divergence is size/distance (both in same units, result in radians).  
03022011, 01:35 PM  #6  
 
Class 1 Laser Join Date: Sep 2010 Location: Athens, Greece
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I didn't know. I'll do some more tests....Thanks...
 
03022011, 09:55 PM  #7  
 
Class 4 Laser Join Date: Sep 2007 Location: Wisconsin
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Good point, Dr. Sid. I was going to add that, but I forgot. You'll see that for values close to zero, the graph of tangent is virtually linear. That is to say y ≈ x. tan θ ≈ θ The same is true of sine.
__________________ A problem well stated is a problem half solved. Last edited by Cyparagon; 03022011 at 09:57 PM.  
03022011, 10:22 PM  #8  
 
Class 3R Laser Join Date: Jul 2010 Location: Olomouc, Czech Republic
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I use different explanation. And that is: what does radian actually mean ? Well .. it measures the 'arc'. If you take pie section of radius 1, its curved side will be of the same length as the angle of the pie in radians. Full circle will be 2*pi. Now imagine very thin pie section .. it's clear that the curvature has little effect on the length of the side opposite to the angle. Also as the central angle gets small, the other two angles are getting close to 90 degrees. So all height of the triangle, length of the arc, and length of the side opposing the central angle are becoming very similar .. and equal to angle in radians itself.  
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