In general, a shorter focal length will produce a smaller focused spot and a shorter depth of focus. In a word, the higher the power, the larger the diameter of the lens.ġ2mm/15mm/18mm/19.05mm/20mm/25mm/28mm/38.1mm/50.8mmįocal length affects both spot size and depth of focus. At any given focal length, a larger diameter lens will yield a smaller focused spot if the incoming beam is expanded to fill the larger lens. Higher power lasers require larger diameter lenses to prevent thermal overload. We can choose the appropriate focusing lens according to the different applications: Material Physical Vapor Deposition (PVD) and Chemical Vapor Deposition ( CVD ) are two processes used to produce a very thin layer of material, known as a thin film, onto a substrate.If you want to know more details of znse materials,kindly click here. Zinc selenide lenses can be divided into PVD and CVD according to different growth methods of raw materials. Ge used to be the lowest cost CO2 lens material because its widespread use in the semiconductor industry created a large supply. As temperature increases, its absorption increases, which leads to thermal failure in high power applications. Germanium (Ge) can only be used in low power applications because it is subject to thermal runaway. It also has a high thermal conductivity which helps transmit heat away from embedded particles. It has a relatively high hardness which helps repel debris particles. Gallium Arsenide (GaAs) is the material of choice in dirty or high- splatter environments. It is also the only material that transmits visible light, a requirement for the use of a HeNe alignment laser. therefore, the material of choice for high-power applications. Zinc Selenide (ZnSe) has the lowest absorption of the common CO2 transmitting materials. Once the CDP is out of its warranty one can take the lid off and give the lens a visual inspection to check if a lot of dust has accumulated on it.6.3 Precautions for the use of laser engraving machine lenses? Raw materialsĪccording to the material Co2 laser focusing lens can be divided into zinc selenide, gallium arsenide, and germanium lens. I make sure I clean the brush on the lens before and after use with another fine brush. One should give the lens cleaner a good visual inspection and also gently nudge the brush at the base (with another brush, not with fingers) to make sure it is not coming loose.
And casual users will normally blindly believe these products than use some knowledge and judgement. Or might come off while spinning and damage the lens. Placing a CD inside while not in use is one option, but it does not prevent dust particles suspended in air gradually settling on the lens.Įven the recommended engineers would have to use some tool - I guess it would be a fine brush or a cotton bud as pressurised air canister would further push dust particles in and a vacuum would be risky.Īnother reason manufacturers would not like us to use CD lens cleaner is that the brush might be loose - the side it sticks to the CD is set hard by the adhesive - causing abrasion. However, dust will accumulate as air is drawn in by the spinning motion as well as fine dust particles collecting during rest. However, if you are cleaning every week or month, that wear can accumulate very quickly.Ĭommon sense and moderation in all things.ĭust on lens should not degrade sound quality.Unfortunately for me (and many like me) my CDP drive mechanism is not sealed ( link), though NAD have been clever enough not to provide any vents on top of the CDP. So, the use of a lens cleaner every couple years is probably not going to do much to damage the equipment. So, not that much dust is accumulating inside the player on the assumption the disks themselves are clean. I suspect you can find people here who have had the same CD or DVD player for 10 years or more and have never cleaned it, and it still works fine. Let's consider how often you need to use the lens cleaner? So, what they really want is for you to not use the lens cleaner within the warranty period. Then you would want to collect on the warranty. You could use a good lens cleaner or you could use a lens clearer roughly as abrasive as sandpaper. It represents something they can't control. I suspect that most CD maker recommend you don't use a disk type lens cleaner. Slightly off the topic, but I bought an Epson printer years ago, that said if I didn't use Epson paper I risked damaging the printer.
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