The
machine vision industry is pretty small, so when it comes to
developing new technology we tend to hang on to the coattails of the
big boys. Lighting is a good example. I think I’m right in saying
that no one is developing LEDs for machine vision. Instead, the
vision lighting companies have to utilize what’s being churned out
for the higher volume applications, like industrial and residential
lighting.
These
days it seems LED manufacturers are working on ever bigger LEDs, and
many are finding their way in to machine vision lights, like the
Monster
series
from Spectrum Illumination. The problem I have with these is that
they are prone to creating hot spots. Interestingly, judging by the
lens
optics diagrams
on their website, smartvisionlights has recognized this problem and
tries to shape the light to reduce the problem.
Some
engineers I work with take the view that a sufficiently thick
diffuser is all that’s needed to smooth out the light, but in my
view that wastes photons by reducing the total output. I would rather
see a higher density of small LEDs, which is the approach taken by
CCS
in most of their lights. You might notice though that even they’ve
jumped on the high intensity – big LED bandwagon.
Now
I appreciate that mounting LEDs takes time, which it probably why
CCS’s lights are among the more expensive, but I’ve also found
the light they put out to be some of the most uniform. I guess you
get what you pay for, and I’m willing to pay extra to get more even
illumination from a higher quantity of lower output LEDs.
1 comment:
Spectrum Illumination has long offered various lens options as well. For example, most lights are available with 12, 30, or 50 degree optics at no additional charge. Or you can choose wide angle or even line generating optics.
I tend to recommend the large LED "engines" when greater intensity is needed for flooding larger areas, as in robotics. But small fields of view often mean precise inspections demanding a more even illumination source.
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