Testing: Can you weld an optical prism and a diffusor into one piece?

During the years, many of our clients have posed us this question, so we decided to check it out!

Karsten inspecting test welding

Technical Sales Manager Karsten Lindorff shows
the integrity of the welded materials.

We went into our lab where we tested welding various types and combinations of diffusors and prisms by ultrasound welding. As an example, we tested welding a PMMA prism with a PMMA and a PET-diffusor. Afterwards, the samples were tested in a climate chamber at different temperatures and at different air humidity.

The result
Due to the hygroscopic state of the materials, the materials either expanded or contracted when cycled in the climate chamber. This resulted in mechanical stress that caused folds and bend-up.

Our conclusion
It can be tricky to weld a prism and a diffusor to one piece. To succeed the materials need to be normalized at the same hygroscopic state in advance which can be a relatively time-consuming task.

Does it mean, we’ve given up finding a solution? Never. We will continue testing and look forward to sharing more results with you.