The 150mW laser cost 50eur, the 3W led is 2eur.
I don't know how hard is to focus LED but I select 3W as this is made on
one die, so it's more close to point source. I respect Volkan job as
it's perfect result, and waiting 20 minutes is not bad if result is
known to be good.
About apertures.. For raster scanning the aperture should be very fine,
as you say in range of 0.05mm or les. But for vector scanning the finest
aperture is the same width as finest trace (0.2mm for example)
So seems that noone was already try to use hi power led.. (I found few
experiment on net with low power UV leds in range of few miliwats to be
unsucess..) Seems that I need to try what is all about. (LED already
ordered...)
On 09/16/2013 08:11 PM, designer_craig wrote:
> The 150mw or even higher power UV lasers are available on Ebay, they are used in BlueRay DVD players. An LED would work but it will take a very long time to expose a board. You need lots of joules/sq mm to activate the resist. The exposure spot area is going to be around .05mm to get good pattern definition and its just not going to be possible to mask and focus and LED to that level with any kind of power. Most higher power LED's have multiple junctions which means they are not point sources and such will not focus to a point.
>
> The laser Volkan was using was in the $30 range from Ebay, its best to use one with a glass lenses for better focus and less loss.
>
> The laser module with heat sink was mounted into an ink jet printer shuttle, the board moved in the Y direction on a custom built bed below the laser. The bed was driven by a stepper motor driving a lead screw. He built custom electronics to provide the laser video modulation it was was timed by the plastic head reader strip inside the ink jet printer. As the head moved across the carriage the laser was turned on and off. Once the head scanned across the board the bed was moved for the next pass. He only wrote in one direction because of technical issues with reading the plastic sensing strip.
>
> Even with the carriage moving at full speed in both directions it took about 15 to 20 minutes to write a 150mm x 75mm board, but the image was spectacular.
> Craig
>
> --- In Homebr