Tuesday, April 23, 2013

Building better cameras

Bad news: that $3,000 camera you just bought isn’t perfect. But it’s not just your camera. No camera is really perfect.

As every good mechanical engineer will tell you, tolerances and variation in manufacturing mean that the sensor, (that little square of photon-capturing silicon,) is not going to sit exactly on the optical axis of the lens, and neither will it be perfectly perpendicular.

Depending on just how the sensor is mounted, this means that the image will be slightly out of focus in some areas. Most likely, I’m surmising, across diagonal corners. In most machine vision applications this might not matter, but I suspect that as resolutions increase and pixels get smaller it will become more of an issue.

Good news: Kasalis, who build machines that mount CCD and CMOS sensors, are working on ways to improve sensor positioning. I learnt this from “Adaptive software eases camera lens-to-sensor alignment” published in Laser Focus World, March 2013, but you can find out more by visiting the “Active Alignment” page on the Kasalis website.

If you’re wondering why you should be interested, let me briefly explain. If you use cameras you should (a) know how they work, and (b) understand what differentiates the inferior from the superior. Clearly, one such factor will be the precision of the sensor alignment, for which we will no doubt be charged a premium.

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