Re: Resonant mirror noise

Posted by Power, Rory on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Resonant-mirror-noise-tp7588458p7588475.html

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Thanks, yes this seems to be the general consensus. I believe we can build something sealed with the scan lens after the resonant mirror acting as a window.

Regards

Rory

…………………………………………………………

Dr. Rory Power
HFSP Postdoctoral Fellow
Morgridge Institute for Research
Medical Engineering | Huisken Lab
330 N Orchard St, Madison, WI, 53715
Tel: [phone]
[hidden email]<mailto:[hidden email]>




On Jul 26, 2018, at 10:55, Craig Brideau <[hidden email]<mailto:[hidden email]>> wrote:

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To add to the chorus, basically the scanners need to be in a sealed
enclosure. It doesn't need to be in vacuum, (although that would really
help) but as long as it cannot transfer sound pressure easily via air it
will be considerably quieter. Note your scan lens becomes the window for
the enclosure; it has quite a bit of spaced glass so it will probably be a
good sound absorber. A little sound dampening foam may still be necessary
on the exterior, just make sure you can still safely dissipate any heat
from the scanners and don't smother the thing completely. I have an early
resonant confocal system that shrieks when in use, and a system which is
newer by a few years, and the newer one is much quieter. On observation,
the new system is simply boxed up better with thicker walls and no gaps
from the interior to the exterior.

Craig

On Thu, Jul 26, 2018 at 8:53 AM Martin Wessendorf <[hidden email]> wrote:

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Dear all--

I'm going to guess that the obnoxiousness of the sound may be a
function, in part, of the age of the listener.
See: https://link.springer.com/article/10.1007/s00420-014-0951-8

--Along those lines, I once had a digital watch with an unusually
high-pitched alarm that I (at age 60) could barely hear, but the sound
of which drove my sons (in their 20s) crazy.

Martin Wessendorf




On 7/25/2018 9:33 PM, Power, Rory wrote:
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Hi Mike,

Thanks for your reply. I was rather referring to an 8 kHz fundamental
oscillation. The noise is quite unpleasant - I’d hate to hear the 4 kHz if
that’s worse as you say.

Isolation should be possible. Perhaps combined with some foam we’ll
arrive at a workable system.

Yes, I assumed the same. Thanks again.

Regards

Rory

…………………………………………………………

Dr. Rory Power
HFSP Postdoctoral Fellow
Morgridge Institute for Research
Medical Engineering | Huisken Lab
330 N Orchard St, Madison, WI, 53715
Tel: [phone]
[hidden email]<mailto:[hidden email]>




On Jul 25, 2018, at 21:18, Michael Giacomelli <[hidden email]<mailto:
[hidden email]>> wrote:

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Hi Rory,

8 KHz unidirectional or bidirectional (so 4 KHz fundamental)?  The 8 KHz
scanners are usually not that bad even at maximum amplitude because the 8
kHz tone is a lot harder to hear and essentially all the harmonics are
out
of audible range.

For 4 KHz at larger deflection angles you either need hearing protection
or
to really isolate it from the room.  A metal box around the scanner and a
window on the input port so that air cannot pass in/out of the scanner
helps a lot. This is how most commerical systems work.

I don't think the model matters; the noise comes from pushing air, so
for a
given mirror size and deflection angle the noise power is going to be
almost constant.

Mike

On Wed, Jul 25, 2018 at 9:03 PM, Power, Rory<[hidden email]>
wrote:

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Hi Confocalists,

We’re trying to circumvent the annoyance of resonant mirrors screaming at
8 kHz. I was wondering whether anyone has a recommendation for
constructing
soundproof containment?

Generally were using inexpensive resonant mirrors from EOPC:
http://www.eopc.com/sc30.html

Also, does anyone know whether the more costly resonant scanners used for
confocal/multi-photon laser scanning microscopies are any better in this
regard? Were not hugely concerned with other attributes (simply for light
sheet microscopy stripe suppression) just the piercing noise.

Many thanks in advance!

Rory

…………………………………………………………

Dr. Rory Power
Morgridge Institute for Research
Medical Engineering | Huisken Lab
330 N Orchard St, Madison, WI, 53715
Tel: [phone]
[hidden email]<mailto:[hidden email]>







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