Lenses have worked perfectly for thousands of years BUT laser beams have only been around for about 60 years Yes, it's still light waves/rays and will be refracted by lenses in exactly the same manner as always. Normal light is more or less uniform intensity across the surface of a lens whereas the Gaussian profile of a laser beam means it has most of its light INTENSITY at and around the centre of the beam. Light refracts (bends) as it passes through a lens which is designed to direct all light energy to a common point (the focal point). This means the outer edge of a lens must refract the rays more than those at the centre. Our laser machine lenses are manufactured with the age old (and simplest to manufacture) form of lens geometry.....spherical. This shape has imperfect focusing properties called aberration. Thus, light from the outer edge of a lens focuses at different points to that through the center. For uniform light this weakness is hardly noticable, perhaps a bit of blur if you look carefully. However, for a laser beam with its maximum intensity (its max ability to damager material) at the beam axis, this becomes a problem. A lens may have a nominal focal point that would apply to normal light, but pass laser light through it and the maximum intensity at the axis of the beam meets the least refractive axis of the lens. Bad news.
Hence the title of this video.......they stay married (with all the imperfections) for the sake of the children and to the outside world all seems well.

This video is some background about several months of test work I have conducted using various beam sizes and many lens types to examine the inner workings of this imperfect "marriage".

Most will not be interested in the large report of my tests and findings because on the surface, laser machines do aproximately what is expected of them without ever needing to "lift the hood". If you have an interest in the report I produced then please contact me via this private contact form.
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