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Is it necessary to measure laser beams with Power and Energy Meter equipment?
As all technical machines, industrial lasers and other optical delivery systems degrade over time. Power and Energy Meter is a diagnostic tool which help to verify and quantify wether the laser system is delivering the right amount of energy or power. It needs to be stressed that precise measurement of energy is critical in most processes performed by lasers. -
Why does a Power and Energy Meter have to be recalibrated?
Similarly to a voltimeter, an ammeter or other pieces of test equipment, the Power and Energy Meter must be recertified and recalibrated on periodical basis. It is highly unlikely for the P&E Meter to drift or fail over time (it is not constantly exposed to laser energy, like a sensor is for example) but still, such possibility exists. That is why, and also according to ISO standards, it is a general practice to have the P&E Meter recalibrated and recertified. -
Which of the two types of lenses should be used - meniscus or plano-convex?
The correct type of lenses is usually specified by the manufacturer and can be found in the machine's manual. But the basic difference between them is that plano-convex lenses are usually found in workshops which cut thicker materials and are more likely to be found in American and Japanese machines, whilst meniscus lenses are traditionally used by European customers and manufacturers (OEM's). -
Is it possible to check the quality of the laser beam visually during the cutting process?
Yes, it is. And in order to do that the sparks under the sheet should be checked if they follow the input laser angle and make one line. If they do not make one line and lag the focal position it means the machine should be adjusted. Another thing to pay attention is the colour of the plasma in the cutting area. If the colour of the plasma is blue the machine should be stopped and its constants re-adjusted. -
What should be done if the lens looks fine, but still its performance is deteriorated?
In such case cleaning the lens using liquid soap and a soft tissue should help. But doing so a few things have to be borne in mind:
I. Coated surfaces of a lens should never be touched and the optic element should be hold by its sides.
II. Latex gloves should be used when handling the optics as bare hands might leave oil and dirt.
III. Remember not to use any sharp objects when handling the lens or place the lens on a hard surface. -
What should be done if the lens was replaced but still its performance is bad?
In this case the following steps should be undertaken:
I a. Check lens mounting direction.
I b. Realign the laser beam.
I c. Check the focus spot size and check the color of the plasma (should be blue).
II. If the problem remains check for dust in the machine.
III. A final step is replacing mirrors (turning mirrors or resonator mirrors). Normally mirrors are replaced once a year - by a qualified person only! -
Are there any possibilities of lens-exploding while cutting and what can be the reason of it?
As there are many parameters involved in operating laser machines and they influence the performance of the optics, there are chances that a focusing lens will explode in the machine. Though it is very rare, the reasons may be as follow:
I. Pressure developed by dust that drops on the lens from the inside.
II. The reflected beam focusing on the lens and burning it or making it explode caused by wrong focusing of the beam on the work piece.
III. Thermal shocks and non-radial heat transfer causing pressure and micro cracks in the substrate and the coating of the lens caused by bad beam profile.
IV. Back-spatter and other hard particles that penetrate and hit the lens, resulting in its chipping and cracking caused by high gas pressure.