What diode laser for cold marking of white plastics

Hi there,

I'm new to this site and am impressed by the knowledge in this forum.

I am currently trying to explore what solution works best for one of my flatbed laser systems (Epilog Summit) having it equipped with a UV/405nm laser for cold marking of white plastics (carbonizing/pigmenting).

Can anyone tell in which direction I should investigate regarding the laser hardware? Would UV laser be the best source or maybe a less dangerous 405nm wavelength? Would it work to take for example a 3 Watt CW mode DPSS source and use a Q-switch for pulsing? Is there enough power left with the Q-switch for marking the plastic in an acceptable time, like 10 characters with font size 12 in 10 seconds?

Furthermore an address where I can buy a laser diode and who could help with information would be interested to.

Please advice, all information regarding hardware, safety etc. is welcome

Personal information:
I have over 12 years of experience working with CO2 (10640nm up to 200 Watt) and Fiber/YVO4 (1064nm up to 30 Watt) lasers as a technical engineer for a multinational manufacturing laser systems and know quite good al of their applications.

Best regards,
Laser man

Sorry I don't have anything useful to add to your search, but maybe you can help me with mine? I'm trying to find an affordable laser marking head & controller for up to a 90W CO2 laser. So far, my research has lead me to extremely pricey marking heads ($10k+).

I wouldn't think a UV laser would be great for white plastics. I thought they have to be pigmented in order to absorb the energy in the UV wavelength, whereas CO2 sees those types of materials as opaque (which you probably already knew).

Edited 1 time(s). Last edit at 01/21/2014 08:32PM by MrBaz.

... you can mark/engrave white plastics/paper with 445nm-diodes and powers >1Watt pretty good, but not so fast like with CO2-lasers -- for 405nm-diodes I'll expect powers >400mW for similar marking capabilities, but 445nm with higher powers is more common/available and so cheaper to obtain ...

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Viktor
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I have been away for a while, that why a reply delayed

@ MrBaz, UV lasers are a good solution for cold marking, depending on the type of UV laser and that's what I try to find out. Plastics with "laser"-additives can be marked with wavelengths up to 1064nm, even some for 10.640nm.
What do you mean with a laser marking head and controller, a working galvo laser or just a laser source with RF?


@ Viktor, can you tell me what type of laser would be best to use, would that be a more sophisticated DPSS or just a 200 mWatt pointer as shown here marking plastics (video).

Next to the Epilog I have a working galvo scanner suitable for a pulsed 1062nm wavelength IPG laser, but then without IPG laser source. The scanner can be adapted with UV mirrors and F-theta F100 lens. I think this system would be a better choice due to the focus tolerance. But what hardware would I need (CW or pulsed, beam expander, dpss or fiber etc.)

Br. Frank

How can one "cold mark" with laser
when the basic laser heats a surface to cut/mark it?

It may melt letters/numbers into material
but not going to be easy to read white melt on white?

Hi Frank,

the uasbility of a laser on specific materials is a matter of wavelength+power - with 200mW@405nm this is a tight value, 2000mW@445nm should be better suited. The next essential value is the price ...

With the galvo-scanner -- simply replacing the fiberlaser with adiode won't work!
The fiberlaser has a really superior beam quality, so you have no problems to focus the beam to some ten microns in 300mm distance.
With a 445nm-diode across a galvo-scanner with maybe 200mm focal distance I've got not a spot, but a 'bar' with 400x100 microns, what's the far-field shape of the emitter inside of the diode ...

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Viktor
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Call for the project "garbage-free seas" - [reprap.org]

Hi Victor,

I see what you mean, I never looked at the beam quality/being square and almost took my changes with this item 3 Watt 445nm laser Output beam at aperture: 1mm x 3mm

Probably having a round beam by a different source makes it expensive then......
If I had to spend about 2 - 5 K-euro on a laser system, it would be acceptable, in case you have a good idea on a laser system for that budged, it is more than welcome.

Frank

... I have some offers for pulsing fiber-lasers with powers of 10 to 20 Watts CW or 2kW to 10kW pulsing ... beginning with 7k€ without VAT ...

And seen recently a Q-switched NdYAG with 3W CW and 20kW pulsing for around 3k€ from Hongkong

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

7k€ is a bit above my budget. Are these fiber lasers 355 or 405nm lasers?

... this fiberlasers are pumped with 975nm-diodes and emits 1070nm with an extraordinary precise beam

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

The wavelength is to big, I would need uv or at least violet.
Do you have experience with tripling a wavelength with chrystals? This would probably only work with end pumped?

What would be my chances using a 3Watt CW 355nm and working with a separately bought q-switch. Could I get a beam emission of 200mW and a pulse energy of 10µJ?

Frank

... most doubled or tripled lasers are NdYAG's -- but you loose most of the power ... most of the DPSS green laserpointers with 1mW green emitting are 'pumped' by an IR-diode with 500mW!

I have a pulsed TAE-N2-laser, that is powered by 25kV and emits 200ps short pulses of 337nm with maybe 80µJ (around 400kW) pulse energy -- but the beam-quality is poor ... not really a laser-beam, more an UV-flash-light

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]