So you once more "read" my text without understanding anything. But you don't react with follow-up questions but by writing text in perpendicular directions.

Still no response to the questions or problems I have mentioned several times. Do the design issues go away if you ignore them?

Of course a CRT has a ray. I already said they had that similarity, several times mentioning electron beams. Had you read my posts, you would not have had a need to capitalize and bold Cathode Ray Tube. You would instead have been able to comment on the issues I did bring up about comparing a CRT with a rasterised laser projector.

I don't expect the light to persist on the target. I expect the light to persist in the viewers eyes. The persistence of vision means that our eyes will be fooled to see the average intensity instead of the very high impulse energy followed by a long time of black. If you have ever seen a laser show, you would know (and not spend time trying to convince people of something else) that the XY laser output will show up as persistent graphs despite being projected on target surfaces without afterglow. Don't you realize that a large number of people on this forum have been to a disco and seen a laser in action. This isn't academic. Most people do already know that it works. It is irrelevant why it works. The theoretical knowledge of how it works is irrelevant when you can prove it by just looking at a laser show in action.

You talk about a CRT having long-persistence phosphor in this and other threads. Modern CRTs don't use that. I have told you before that todays monitors do not need the phosphor to be charged for a number of frames to reach full intensity. They reach the full intensity on one pass. And they lose almost all intensity long before the next trace of the electron beam. And todays CRT monitors do not continue to light the phosphor for a number of frames after the pixels are turned off. If you don't believe me, you can photograph the monitor with a suitably short shutter time. We don't need the afterglow to see an image on a CRT. That is also why we have problems with intermodulation when using a modern CRT together with fluorescent lamps. Both the lamps and the CRT produces high-frequency flimmer and our eyes may fail to se the flimmer from the CRT or the lamp but we can see the flimmer from the difference between these two frequencies.

You once more prove my point with your example with your laser pointer. Your laser pointer with very low intensity (probably 1 to 10mW) is visible when you keep the point still. Try to cover an area with the light, and the light density will be too low. You talk about 50m. Yes, the specific thing about a laser is that as long as the air is clean, the laser light will stay focused so you will still get almost the same intensity reaching the target at a larger distance, but only as long as the point is stationary! What does reduce the intensity with distance is the percentage of light that gets reflected straight back. With a flashlight, you will have a large loss of light towards the target since the light cone expands. This means at 50m, very litthe of the flashlight output will hit the tree, so even less light will reflect straight back.

You can find photos on the net of XY projectors drawing on clouds. This is possible because an XY projector will spend a very large percent of the laser light actually drawing visible lines, compared to a raster display.

Your suggested raster had 50k pixels. Guess what happens when you dim your laser pointer with a factor 50k? Do I really have to tell you what happens with the visibility?

How fast to repeat a pattern? Depends on the complexity. Most users produce geometric patterns or constantly changing patterns. But you still ignore the simple fact that all the reasons you use to complain about an XY projection have a simple solution. And that is not rastered output of laser light. But a dia or LCD projector can't do what a vector-driven laser projector can. And neither can a rasterised laser projector. So why talk about a million-dollar design that can be matched by a 2k LCD projector or a $100 dia projector? That is just stupid. In the other direction, a $100 vectorized laser projector can do things a $100k video projector can't.

Do you really recommend people to use a million-dollar technology to get a $2k result?

Back your argument with something simple: Post links to a suitable laser, together with information how you will modulate it at MHz speed. Or are you still convinced that the raster output will have the same pixel intensity as if the laser just lit a single point?


A large number of web projects have already proven that a tiny 8-bitter can handle an XY projector.

Can you now explain to me how you get your 12MHz 805x to produce reasonable bitmaps at 30 or 50Hz speed? Remember that it wasn't more than a couple of weeks ago that you didn't believe a 805x to be capable of generating graphs on a matrix printer. A printer with 8x6" paper size and 72dpi and a printing speed of one minute/page would need to process 250k pixels/page or 4150 pixels/second. Why would that be an unreasonable speed?

Your 256x192 display with 30fps resolution would have to produce 1.5 million pixels/second. It should be obvious how hard it is to create new frame buffer data at that speed for most microcontrollers. So your 805x would be limited to handing out static data. But why do you not clearly say that your "works just fine" means a solution limited to just shifting out static data?

Now do answer the following:
- what laser would you use to allow the dot to be visible when it only spends 1/50000 of the time illuminating the dot?
- how will you modulate this laser at MHz+ speed?

Do not just continue to stampede forward with "MUCH easier" when you do ignore all the real problems.