Hello TI,
I'm currently trying to use a light engine fitted with 0.96" WUXGA DLP9600 & DLPC410 for 3D printing application.
For starter test I printed a straight hollow column, therefore the light engine was supposed to project the same cross-sectional image at exact same location for each layer.
The light engine was securely locked in place but here's the printed part:
The projection shifted in diagonal direction by a small amount every 40ish minutes then back to normal in about 5 minutes and repeated itself.
I checked the image files on PC screen but no abnormality found. I examined the printed part again and it seemed that the offset was smaller than a pixel.
In order to determine the amount of offset I performed another test. Using a Mylar film as projection screen with marked masking tape on top as reference, I was able to record 600 of consecutive projections under a macro camera which was mounted on a rock steady tripod. Let's take projection 227-228 as an example:
The thick bar in the middle was 6 pixels in width. There were two bars and I deliberately put the left one just outside the edge of the frame by fine tuning camera position.
Everything looked normal till projection no.227 then the image suddenly shifted to the right in projection no.228, with part of the left bar entering the view.
With the help of Guideline function on Photoshop, the amount of offset was measured 1/6 pixel:
The image shift happened in both X and Y simultaneously (i.e. diagonal) but I only managed to get it down on tape in one direction due to the lack of professional monitoring equipment.
I repeated the test quite a few times and the offset amount varied from 1/7 to 1/4 pixel, instead of a constant number.
The image shift was just too regular to be input signal or mechanical structure related.
So, what are the reasons of such a behaviour and how this problem can be fixed?
Thank you in advance.
Daniel