View Full Version : Engraving diffusion patterns...

Ted Larson
05-04-2010, 6:12 PM
I am working on a project where I would like to side-light a small acrylling panel using an LED and have the whole panel light up. I found an example item and took it apart, and found that it has this nice diffusion pattern silk-screened on the back of the piece of plastic, that reflects the light. Looks like the perfect thing to reproduce by laser etching the acrylic.

Can anyone post some pointers on the easest way to lay down a diffusion pattern in Corel Draw or SolidWorks? How do you get the non-uniformity?



Dan Hintz
05-05-2010, 5:49 AM
You'll need to post a pic of the pattern for the best help... I'm trying to imagine a non-uniform diffusion pattern, but it sounds like a contradiction in terms...

Martin Boekers
05-05-2010, 9:49 AM
Dan, your right a photo is needed to see the effect.

What I'm thinking offhand is to render some cloulds in PS or Photopaint then hit it with a gaussian blur to get a non-uniform effect.

Just a guess though without an image.


Ted Larson
05-05-2010, 11:49 AM
Dan, your right a photo is needed to see the effect.

Photo attached. What I meant by non-uniform, is that although the dot spacing is uniform, the dot sizes change the further away from the light source they get. In this case, the light source is the notch at the bottom. If all I had to do was lay a uniform grid of dots down, that would be easy. It's making the dots different sizes which is the problem.

All suggestions appreciated!



Jon Colley
05-05-2010, 12:16 PM
I think I can point you in the right direction:

Design your shape and then fill it with a gradient fill (white to black).
Convert this to bitmap at 500dpi and then change the mode to 1-bit.
Select Halftone, set the screen type to Round and 1 line per inch.
This should give you the desired effect.
You can tweek the settings to get it perfect for what you need.


Dan Hintz
05-05-2010, 7:13 PM
Several ways you can do this, but I'd probably go with step/repeat.

Draw one circle of desired size at the bottom. Step/repeat with desired distance between steps. 30 seconds

Copy circle above first, increase size slightly. Step/repeat.

Entire sheet would probably take 5 minutes to create.

Another way, which might look more uniform, like a fan of dot-filled "lines"... draw one line with increasing dot size. Fan it out using step/repeat with an angle rather than an X/Y distance, center point of the angle pretty far away to get a large fan-out.

Rodne Gold
05-06-2010, 8:26 AM
I have done a lot of edge lit stuff - the way to get the even spread of light in the graphic is to use a gradient fill over the WHOLE sheet - and then to use that to fill the graphic where its solid engraving , if its a vector , just powerclip the gradient inside the vector boundary.
You can use your laser raster driver to engrave a whole panel for even lighting if you want , just use the gradient fill and engrave it...the laser driver should do the 1/2toning correctly
You need to experiment with the gradient fill to get the correct fading for even lighting.

Ted Larson
05-10-2010, 9:51 AM
These are all great suggestions! I will give it a whirl here hopefully later this week, and I will post my results.