2 SPOT SIZE AND FOCUS @SarbarMultimedia

Uploaded February 2026 | Updated September 2026, 1 week ago

New laser users often choose diode lasers as an "easy way" into laser technology. With no water cooling or beam alignment issues there are many benchtop units that look really attractive.
You can buy photo engraving software that promises great resultsp and MANY well-meaning hobbyists that are generous enought share their "here's what I do". All depend on knowing your machines "spot size". The blatent lies on spec sheets have driven me to distraction.The promises of simple and easy is a misleading fantasy for naive new users. Photo engraving is a very alluring subject, however, your machine may not be capable!!!!
This little series will soon tell you if your machine is capable and will set your expectations accordingly.

RDWorks Learning Lab 222 Beam combiners A new approach

RDWorks Learning Lab 208 Can I Remove the Focal Point

TangerineTiger 13 Lets Compare RF and Glass tubes

Fiber Laser Learning Lab 11 We are no longer Flying Blind

RDWorks Learning Lab 170 Lets Focus on Lenses Part 4 (first results)

RDWorks Learning Lab 226 Can my Beam Collimator Work

RDWorks Learning Lab 207 The Importance of Beam Intensity

RDWorks Learning Lab 163 Lenses Part 2 Lets Focus

RDWorks Learning Lab 181 Redsail clone upgraded head

$RDWorks Learning Lab 210 Lets Focus on Focus AGAIN The dictionary describes a focal point as that place where parallel rays of light passing through a lens are refracted to converge on a single point. That may apply to visible light for cameras and telescopes where light sources are uniform and lenses are high precision and usually multiples, but in the world of Chinese lasers things are a long way from that dictionary definition. The use of a single lens and then a choice of just two forms, plano convex and meniscus, is the first disadvantage. The simple spherical geometry of these lens forms will never achieve that dictionary perfection. The longer the focal length of the lens, the greater the imperfection. The single feature that ALL lasers beams posses is a non-uniform intensity profile. The perfect laser beam will conform to a Gaussian intensity distribution. ( a bell shape graph) where the central light intensity is many times greater than the outer regions of the beam. Combine the focussing weakness of spherical lens geometry with the non uniform intensity within the laser beam and we no longer have that idealized model of focus that we are all taught. We set the focal point for a lens to that distance where we create the smallest burn spot or the thinnest drawn line. This is not setting the LIGHT focal point but that point where the the light INTENSITY is sufficient to damage the material we are marking/cutting . I clearly demonstrate that the traditional model of focus is of very limited value in our weird world of lasers.$