Seeing is believing

In “Better backlighting” (June 9th 2009,) I linked to an article on MachineDesign.com that discussed the benefits of using a telecentric backlight. Well I was able to see one of these lights on the Edmund Optic stand at the Robots & Vision show, and I can confirm that it performs exactly as advertised.

Edmunds had a nice demo setup consisting of two cameras viewing a screw thread. One camera used a regular backlight while the other used the new TECHSPEC® Telecentric Backlight Illuminator. The difference in edge clarity was really quite astounding. If you click the “Technical Images” tab on the page I’ve linked to, you’ll see what I mean.

Unfortunately though, the light needs a lot of depth behind your target part, which isn’t always available. At $800, it’s not exactly cheap either, although if you need to make a precise measurement it has to be the way to go.

If you just can’t create the space needed, Advanced Illumination were showing off a “collimated” backlight at the show. The size and shape of a regular backlight, it used a film to provide a degree of directionality to the emitted light. Not telecentric, but if you placed at a distance behind your target it would yield a similar effect. Unfortunately I can’t find it on their web site, otherwise I’d give you a link.