I think I found the answer, looks like it's as simple as, the optimal wavelength is the wavelength that is absorbed by the material.

Never really thought of it that way but it certainly sounds like a very good rule of thumb.

Tweakie.

Well, I never did get any response from Tomura Kazuki with his TomTom plugin, so I guess it's out of the question. I do wonder however whether the Mach3 plugin or DotG are smart enough to not stupidly scan the entire area line by line thereby going over large areas where engraving isn't necessary?

I do wonder however whether the Mach3 plugin or DotG are smart enough to not stupidly scan the entire area line by line thereby going over large areas where engraving isn't necessary?

Nope 

Tweakie.

Warp9 have now added the ability to laser reproduce (raster) 8 bit photographic images using their ESS and the v221 release Mach4 plugin. It is still very much in the beta stage and does not have a GUI but an excellent and detailed ‘setting-up’ tutorial has been prepared which should get any potential users up and running in no time. It equally supports vector laser work and is suitable for use with Diode, RF and DC excited CO2 lasers.

I have not had a chance to try it out yet but for those who may wish to do so, the full documentation and further details can be found here;  https://warp9td.com/index.php/faq/faq-mach4#LaserSetup

Tweakie.

Tweakie:

  Thx, nice to know. Nice to see lasers getting some respect.

Art

I had been hoping that other Mach4 users with lasers and an ESS may have tried out the laser raster image reproduction but overall there does not seem to be much interest.

Considerable improvements have now been made with the latest ESS plugin Build 227 and Mach4 Build 3882 but the plugin is still lacking a GUI and key runtime features such as vertical step-over adjustment and image scaling.
 
Currently the vertical step-over seems to be set at one pixel, making the scan lines clearly visible and there is a definite issue with horizontal registration although this can possibly be improved by gating the laser PWM and adjusting the gate timings – something I have yet to try.

So far, this is the best I have been able to achieve – it can only get better 

Tweakie.

Thanks to Andy at Warp9 who explained to me how to fine tune the delays it was just a matter of trial and error before I was able to set the horizontal registration for my chosen feed-rate.
After 3 or so attempts it is now pretty close.

Tweakie.

Although I am using mach4 a bit more often nowadays I just had to try the same fox image using Mach3.

Tweakie.

Way back in 2014 I posted the simple solution I use for controlling my laser output power using the Mach3 generated PWM signal. https://www.machsupport.com/forum/index.php?topic=12444.msg194200#msg194200
That method, although just fine for me, is not suitable for lasers which use an Active High TTL input so an alternative was investigated.
Although it is a little more complicated because a 5 Volt power source is required, using a basic logic IC the Mach3 generated PWM can easily be gated ON / OFF using the M11 / M10 command set thus controlling laser output power.
I have attached schematics for both TTL(High) and TTL(Low) versions of the same concept.
By referring to the truth table you can see that condition C would be used for laser OFF with condition D used for laser ON (at the designated PWM) and condition F would be used with 100% PWM for full power laser output.

Food for thought perhaps ?

The 74LS00 is a NAND gate so there should be a circle on the output to represent the logic inversion. This would make the difference between the PlanB and PlanB2 more obvious.
The unused gates could be paralleled to increase the output drive.

Using 4000B series CMOS would allow for 5V or 12V logic levels. The MC14011BDG NAND gate has twice the output current (8.8ma) as the average 4000 series gate (3.4ma). That's slightly more than the 74LS00 (8ma).