Need Quick Answer!!

[WilliamD]

I'm about to bid and buy the focus lens for my laser. There's a plano/Concave that's .5" in diameter, and 50mm FL. What factors does the plano/Concave introduce? I'm just trying to cut 2 and 3mm mdf and acrylic. I believe the 50mm fl means that the spot will be 2 inches roughly away from the lens. Thats plenty far for me. The bigger question is what the spot size would be with that lens? Some quick help would be greatly appreciated!

[smartcut]

Hello !

No problem. You need a 16 mm wide plano-convex ZnSe lens with a focal length around 100 mm. Price around 50 USD in China.

For a CO2 laser :

Spot diam (mm) = 0.013xM²xf/D

DOF (mm)=0.027x(f/D)²

M = 1 if the laser is perfect.
f: focal length
D : unfocused beam diameter (around 5 mm)
DOF : depth of field

So with f=100mm and M=1, spot size = 200 micron and DOF = 7.5 mm

Enjoy !

Philippe

[WilliamD]

THANKS! I really appreciate the info!