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epiloglaserfocus [2024/09/25 01:19] – andrewhowlettepiloglaserfocus [2024/09/27 17:45] (current) – andrewhowlett
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 The laser is focused for maximum intensity which is slightly different that the waist of the focused beam. When I say focal plane I'm talking about the plane of maximum intensity not the plane where the beam is of minimum diameter. This is possibly a nit-picky deatil since it is likely that the two planes are very close together. The laser is focused for maximum intensity which is slightly different that the waist of the focused beam. When I say focal plane I'm talking about the plane of maximum intensity not the plane where the beam is of minimum diameter. This is possibly a nit-picky deatil since it is likely that the two planes are very close together.
 +
 +===== The Cutting Table is not Perfect =====
 +
 +The cutting table is not perfectly level. Nothing is perfectly level. By focusing on different spots on the Fusion Pro 24 table I measured 0.000 at the top left (0,0) corner of the table, 0.025 at the centre of the table, and 0.064 at the far corner (24,24). So you can expect variation on the order of at least 0.035 due to variations in the cutting table.
 +
 +===== How much variation in focus depth is acceptable? ======
 +
 +This is an interesting question. Lasers usually form gaussian beams. For a thorough discussion on the propagation of a gaussian laser beam you can find papers like this on the internet [[https://www.brown.edu/research/labs/mittleman/sites/brown.edu.research.labs.mittleman/files/uploads/lecture21_2.pdf]]. A simple euclidean geometric approximation, assuming that the unfocussed beam width is 1mm, the focussed beam width is 0.13mm and the focal length is 2 inches, gives the table below.
 +
 +|  distance from focus (inches)  |  beam diameter (mm)  |
 +|          0.000                 |         0.13         | 
 +|          0.010                 |         0.13         |
 +|          0.020                 |         0.13         |
 +|          0.030                 |         0.14         |
 +|          0.040                 |         0.14         |
 +|          0.050                 |         0.15         |
 +|          0.060                 |         0.15         |
 +|          0.070                 |         0.16         |
 +|          0.080                 |         0.16         |
 +|          0.100                 |         0.17         |
 +
 +
epiloglaserfocus.txt · Last modified: 2024/09/27 17:45 by andrewhowlett

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