Camera Calibration Grid on Acrylic

[rfer]

Hi All,

I will have a laser pattern on a frosted acrylic sheet (6 mm thick). I will be measuring this laser pattern through this acrylic sheet with a camera and machine vision application. I need to calibrate this camera. I am going to use a dot grid on the acrylic sheet to calibrate the camera. However, I am having trouble finding a resource to print this simple dot grid on the acrylic sheet (black dots for high contrast vs the white translucent frosted acrylic sheet). I have found companies that print on acrylic, but all are for portraits, etc., none for engineering applications, and thus their tolerances are very poor, and as you know I need this dot grid to be near-exact. 

Question: Have you printed on acrylic before for camera calibration? How did you do it? 

I am trying to avoid printing on paper and then gluing it to the bottom of the acrylic if possible. Having the dot grid printed directly on the acrylic is a much more elegant solution that I would like to achieve. 

Thanks!

[Rahulbala]

Hello

I have calibrated the camera using the dot grid before. I have used a thin metal sheet and machined holes on it ( it is accurate) and then placed another black power-coated metal sheet behind the sheet.Now in a 2D perceptive, we can just see a sheet with black holes on it. I am not sure whether this will apply for your application, let me know your thoughts on it. 

Hope it helps !

-Rahul

HIT KUDOS TO CONVEY THANKS

[ng1902]

I haven't done printing on to acrylic before, but I have a few possible suggestions:

• Fix a laminate sheet over the acrylic (black laminate on white acrylic, or vice versa) and find a CNC laser-cutting company near you. Have them cut a dot pattern into the laminate, but not cut all the way through the acrylic. Then either peel the dots out, or peel the surrounding area out, and you have a dot grid. I think a laser cutter should be able to get very good tolerances.
• Affix a mylar distortion target to the acrylic, rather than a paper target. I've use mylar targets made by Max Levy / II-VI before, and they're very accurate. They're also expensive, and might be too small for your use case. Here's a link to their distortion target lineup, mylar targets are down at the bottom.