Hi David;
Thank you for your response. I suspect that it will be choosing the power boundaries to select that will be the issue for many people. At the moment the laser settings are pretty much seat of the pants guesswork. This does not really fit with using a machine that can work positionally to an accuracy of 0.1m. e.g. when we use the jog control, the stepper motors have no difficulty moving the module in 10ths of a millimetre. The laser power setting is not so fine grained and once it is set, that is what you have to stay with.
A small diversion: I think of the laser power in terms of an ink dot being placed somewhere on the page. In the days when newspapers were our main source of news, the papers had little access to technologies that produced colour and the images were all monochrome because only black ink existed for long runs of hundreds of thousands of copies. Colour printing was available but it was far too expensive for printing a newspaper that would be thrown away after it was read.
Printers who printed newsprint or commercial printers who printed by single colour letterpress machinery used a method to get variations in tone despite only having black ink for their printing output. The solution was to print using a halftone method that still placed black ink on the page but could vary its density by means of a halftone screen. Sufficient to say that the process produced an effect that typically suggested that an image comprised black, white and many different grey coloured inks. The image below is instructive.
In this halftone image every black dot has been laid down in a regular grid. The illusion of tonal changes through a range of grey tones is maintained by the dots being printed smaller. The less dense areas are lighter grey than the denser areas. The nose projects a shadow that is pure black. The image resolution is highly magnified to illustrate the halftone effect and the image should be viewed at a distance so that individual dots of ink are not visible. That way you will see the illusion of the grey tones rather than just black ink dots.
One other image that may assist you to understand where I am trying to go with this discussion is a zone system chart; which I have attached to this post just below this sentence. The Zone system was used by early photographers and is based upon Ansel Adams work to describe locating the exposure of film in the correct place.
Each of the labelled tones demonstrates a different tonal value. Black (0) could be assigned 100% power and White (x) could be assigned the off position. Each tone in between could represent a 10% change in value. This type of system would permit variable laser power to be applied to images and improve upon the results that are currently obtainable with a single power setting and dwell time changes. It does not obviate the need for an infinitely variable power adjustment nor one that could be made while the machine was actually running.
An integral part of the laser power is its positioning. I have already acknowledged the machine resolution being capable of as small as a 0.1mm movement. Where I feel an improvement could be made is in the area of positional value readout. Cartesian coordinates are how the machine finds its next location and the software should be able to display where the module is in the ‘X’, ‘Y’ and ‘Z’ positions. The position of best focus must be known to the engineers and it would be helpful if the ‘home’ position for perfect laser focus could be added to the thickness of the workpiece (a new input value) so that the laser would be in perfect focus without the user trying to determine the best dot size for the laser beam.
Other input values that are suggested are start position which I would prefer to be variable rather 0,0, as determined by the machine. If Luban could let us determine our own arithmetically derived start position, there would be no need to jog the laser to the point that approximates where the user wants the laser to switch on. The values which affect laser image include dwell time, speed of movement, impurity density and image algorithm should be available in all modes of operation. For a black and white image, the engineers did not include dwell time settings.
I could make a case for manual adjustment of power and travelling time. The positional stuff should all come through the Luban software because these are known values. The rails and modules do not change their locations from what the assembled machine permits. I would want any solutions to help me to avoid the need to run 40 different tests of laser power and create duplicate workpieces to do so. A manually adjustable power setting and work/feed time would let me use one piece of scrap wood and run numerous tests without having to stop and use my computer and Luban to assemble another series of test conditions.
There you are David, I hope I have made this relatively clear. 
