Need help with laser lens

[fungcie]

I just bought a chinese laser cutter with 130 watt reci tube, but I have a problem with cutting 12mm MDF board, it seems that with 100% power the cutting speed was very slow, after my research it turns out that cutting a thick material will need different focal length lens. My current focal lens is 2 inch. Now I'm looking for a 4 inch focal length lens with the housing assembly. I already search the ebay and find a lot of lenses, but I cant find anyone who sell the lens housing. Can anybody help me where can I buy the complete lens with the housing? Thanks in advance.

[fungcie]

After a lot of inspection and measurement it turns out that the laser tube was fine, the lens was fine, the housing was fine too. The problem is the manufacture was fitting the 2 inch focal point lens in a 2.5 inch focal point lens housing. That's 0.5 inch difference made a lot of trouble.
So I decided to buy an extra ZnSe lens which match the size of the housing and hoping to overcome the problem.
One other question, I already search the internet & wikipedia about the difference between GaAs lens and ZnSe lens and find out nothing about them. Can anyone give me some explanation about those 2 material, which one is better for CO2 laser? Thanks.

[herby08]

Hi there,
go to Lightobject.com Sacramento (Elk Grove) DSP CO2 laser machine & Parts. Solar panel & Electronics Supplier all of Northern California marco there has all what you need for a really good price and super service.
greetings
walt

Originally Posted by fungcie I just bought a chinese laser cutter with 130 watt reci tube, but I have a problem with cutting 12mm MDF board, it seems that with 100% power the cutting speed was very slow, after my research it turns out that cutting a thick material will need different focal length lens. My current focal lens is 2 inch. Now I'm looking for a 4 inch focal length lens with the housing assembly. I already search the ebay and find a lot of lenses, but I cant find anyone who sell the lens housing. Can anybody help me where can I buy the complete lens with the housing? Thanks in advance.

[fungcie]

thanks, I'll contact them if I need anything else.

[Exsecratio]

Originally Posted by fungcie After a lot of inspection and measurement it turns out that the laser tube was fine, the lens was fine, the housing was fine too. The problem is the manufacture was fitting the 2 inch focal point lens in a 2.5 inch focal point lens housing. That's 0.5 inch difference made a lot of trouble. So I decided to buy an extra ZnSe lens which match the size of the housing and hoping to overcome the problem. One other question, I already search the internet & wikipedia about the difference between GaAs lens and ZnSe lens and find out nothing about them. Can anyone give me some explanation about those 2 material, which one is better for CO2 laser? Thanks.

Gallium Arsendie is much more resistant to scratching as well as being more *optically smooth*.
Zinc Selenide is cheap but tends to spall if allowed to become dirty then hit by high power laser beams.
Be aware if using a beam combiner for your red dot that GaAs does not pass red laser wavelengths so the dot will dissappear.
A 75mm focal length lens won't give much of an improvement over a 50mm lens so very little benefit for thicker material.If you do want more depth of field you will need to use a 150 or 200mm focal length lens.
For a simple explanation of Depth Of Field have a look at this
OPLaser support forum • View topic - Understanding Depth Of Field (DOF)

best wishes

Dave

[fungcie]

Thanks for your explanation Dave. I have another question, what do you mean by optically smooth? Does it pass more light through the lens or less distortion?
I would like to try the GaAs lens, how many % improvement do you think it would give compared to the ZnSe lens?
My current machine can't use the 150 and 200 mm FL lens because the cutting bed is stationary. It would need a lot of modification if I want to use the 150 and 200mm. I think the 100mm would be fine without any modification. I'll try them first.

Thanks again Dave.