Use short pulse laser to have small treatment
- source:AMANCIO CNC Machining
The laser pulse of 50% is absorbed in 1 micron deepness. Graph 1, use 355nm " long " pulse laser (Zun Tu) , 266nm " long " pulse laser (in graph) and 355nm " weak point " pulse laser (right graph) of treatment. Current application involves plastic, metal, pottery and porcelain and vitreous base. Till recently, used output wavelengh to be the laser of 40-60ns or above for duration of 355nm, typical pulse, it has in these application on beautiful expression. But, the need that ceaseless miniature changes and much better the additional requirement of brim quality is developing in what drive these laser. Use shorter wavelengh (266nm) can reach admirable resolution and brim mass, but can raise finished cost. In a lot of material, want to use the 355nm laser of shorter output pulse only, can achieve similar result. In the article, we were discussed why can achieve this kind of effect to develop simultaneously a few give typical examples. Use shorter pulse laser to still may have other cost advantage. Because the brim is cleaner, rudimental material lowest, because this has treatment hind need not clean advantage. Two kinds of laser (Coherent Avia and Matrix) the means that uses likeness has optical setting, be about to beam of light expands of Scanlab HurryScan 10 or 14 Zhen Jing, in order to achieve about 4-8 inch the smallest central issue. Can be so above the target the central issue that produces about 20 micron. We had made clear in studying extensively, in a lot of material, need to use the 355nm laser that can produce shorter pulse width and high quality light beam only, can achieve what 266nm machines to be able to compare a result. We are special discovery, it is in pulse width about 20ns or lower, M2 under 1.
3 when, of these material all round fuel factor is reduced greatly. The key is to have pulse breadth so short and the reliable laser of high quality beam of light. Graph 2, use 355nm " long " pulse laser (Zun Tu) , 266nm " long " pulse laser (in graph) and 355nm " weak point " pulse laser (right graph) of treatment. A kind of way that wins shorter pulse width is to lower pulse repetition rate, but the quantum of output that will decelerate a lot of machine to machine craft so. Or, enter laser crystal through building shorter laser antrum aperture and pump of will more energy, can achieve shorter pulse width. When the pulse repetition rate that is as high as 80kHz, the 355nm series laser of Matrix can produce 10-20ns pulse width, pulse energy stability is tall (noise is 1-2% RMS commonly) , quality of beam of light is high (M2~1.
2) . The data of a few kinds of polymer that plastic treatment uses normally in medical treatment equipment is when 355nm absorbency is strong. Typical give typical examples is to get together acyl inferior amine, it is OK short pulse of 355nm of benefit from benefit from. Graph 1 show in laser of 355nm short pulse, 355nm is used above same sample the typical effect that longer pulse laser and 266nm laser have small treatment. Can see, 355nm means of economy will produce indistinguishable result, because this is optimal choice. Get together fat film uptake is fewer, but laser of 355nm short pulse still can produce almost as same as 266nm laser result (refer to a graph 2) . Accordingly, explain again, laser of 355nm short pulse has cost lower with quantum of output higher good point, make its make first selection. Graph 3, the stainless steel sample that uses different laser treatment, a) use 355nm " long " below pulse laser circumstance; B) use 266nm " long " below pulse laser circumstance; C) use 355nm " short " below pulse laser circumstance. When using these organic polymer, the uptake of UV depends on stick accept a structure. Double stick receive material to be absorbed when longer wavelengh, include 355nm. But, the uptake of high saturation polymer suffers be confined to shorter wavelengh, because of laser of this requirement 266nm. Best example is teflon, although be when 266nm,process pure data very hard also. Fortunately, most medical treatment uses the teflon that has chromatic additive in equipment application, although be below visible light condition,also can absorb. Accordingly, the laser of 355nm short pulse of here can produce admirable result. To teflon, choose best laser key to depend on containing what additive. Metal to most metal, the effect that introduces generation of laser of 355nm short pulse almost as admirable like the effect when using 266nm laser (refer to a graph 3) . The result that 266nm laser produces is a bit good, because performance of metallic heat conduction is high,the likelihood is, weakened the good point that the quantity of heat when using short pulse means drops. Below most circumstance, difference of this kind of limit is not quite significant, accordingly, when laser of use 355nm short pulse, the processability that most metal tinfoil paper applies can be admirable. Exceed short pulse laser (make by Raydiance company) have about the pulse length of 500fs, quantitative class under above discussion laser. Basic output is 1 micron wavelengh about. Unfortunate is, the energy of every pulse is extremely low (<10 J/ pulse) , because this cannot use Zhen Jing truly effectively, because 5 micron are less than in the requirement focus size above the target, in order to obtain data of enough cleanness of energy density purify. Accordingly, the beam of light of this kind of laser is provided through the field lens of microscope, use revolving stage coming back to move, is not mobile beam of light. This means handling time to grow, but treatment quality is particularly superior. Because cost is high, the laser of these types is used at taller to machining quality and new technology requirement application normally. What the graph shows 4 times is cut gets together can the detonator of ram. What we machine is a kind of height has stuff only, this kind of material is in be bumped (physics is bumped / hammer is attacked, it is odd laser pulse is bumped even) when extremely volatile strong. Besides the Raydiance laser with cut material good performance, we cannot use other laser. This is very important, because need a kind of production method to form these,get together can ram, the simple method that has a kind to ignite them next (laser pulse is bumped) . Anyhow, shorter pulse can produce cleaner result, pulse becomes shorter, wavelengh dependence falls lowest. We think (hypothesis uptake is big and focus size is small, the energy density that goes up in target content namely is high) , pulse length will show hot effect nearly always when 20ns more than, pulse length comes for 1ns when 20ns may won't show hot effect possibly also; In a lot of application, under the pulse width of 1ns indication heat is affected very small or without the influence. Use flying second laser, we can achieve exceeding and good cut performance, but cost and speed are large-scale two production problems. As a kind of reasonable balance, the leather second laser on the market (for instance the product of Lumera) it is OK to show the treatment quality with admirable generation (refer to a graph 5) machine speed effectively with economy, although its economy be not a patch on uses trade,develop the case of laser with 355nm short arteries and veins. Article author Ronald D.
Dr. Schaeffer is American Photomachining Inc.
presiding apparitor (Rschaeffer@photomachining.
Com) , gabor Kardos is client service vice-president, scott Murphy and David Grossman are applied engineer. Firm network address: Www.
Com. Author annotate: The company that the article alludes and we study medium product is give typical examples only, cannot think the performance of the other product of similar standards is bad -- it is better to be met probably. CNC Milling CNC Machining