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General Mach Discussion / Re: Laser Focal lens selection method
« on: July 05, 2012, 06:58:53 AM »
Hi Andre,
The lens focal length is measured from the centre of the lens to the work.
Line up you machine with your Perspex gauge then measure from the work surface to the position that the old lens was fitted and then, if possible, obtain a new lens with a similar focal length to the distance that you just measured.
There are two common types of lens material used with CO2 lasers. The yellow colour lenses (seen on ebay) are made from Zinc Selenide (ZnSe) and are the cheapest – the grey colour lenses are made from Galium Arsenide (GaAs), are usually quite expensive but are considered to be more hard wearing.
I have lenses of both types but the ZnSe is the one I use all the time.
Remember to fit your new lens with the convex side towards the laser tube and the flat side towards the work.
Tweakie.
The lens focal length is measured from the centre of the lens to the work.
Line up you machine with your Perspex gauge then measure from the work surface to the position that the old lens was fitted and then, if possible, obtain a new lens with a similar focal length to the distance that you just measured.
There are two common types of lens material used with CO2 lasers. The yellow colour lenses (seen on ebay) are made from Zinc Selenide (ZnSe) and are the cheapest – the grey colour lenses are made from Galium Arsenide (GaAs), are usually quite expensive but are considered to be more hard wearing.
I have lenses of both types but the ZnSe is the one I use all the time.
Remember to fit your new lens with the convex side towards the laser tube and the flat side towards the work.
Tweakie.