Monday, March 12, 2012

What can TDI do for you?

The TDI in question refers to the Time Delay Integration linescan cameras that Dalsa launched a few years ago. Intended to overcome linescan’s hunger for light, these have a multirow sensor that in effect tracks a region of a web. This gives the effect of a longer exposure time, so letting you run the surface to be inspected at higher linear speeds.

Now realizing that my opening paragraph may have done more to confuse than educate, let me steer you to an article that explains the benefits of TDI cameras by way of a real-world application. “Automating Solar Cell Inspection,” published February 13th 2012 on the SolarNovus website, is an article from Teledyne Dalsa describing the use of TDI in PV inspection.

This article is interesting for a second reason too. One of the more successful techniques in PV panel inspection is to use IR backlight. Basically, the light shines through the silicon, highlighting cracks and other defects. Unfortunately though, camera sensors have fairly low sensitivity to the near IR, forcing the use of longer exposure times. So with the TDI camera discussed in the linked article Dalsa have increased the IR sensitivity. I think that’s what people call hitting two birds with one stone.

Now back to my question: what can TDI do for you?

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