update on scope room dustiness

August 26, 2016 at 4:39 pm | | hardware

A while ago, I installed a very simple filter for the air vent in our scope room. It barely did anything, honestly. The “filter” is nothing more than a very loose mesh of fibers.

So I’ve bumped up to a 20x20x1 inch MERV13 pleated air filter with a paperboard frame. It fits perfectly between the vent and the grate. I even did some actual tape-measuring before purchasing. :) With a little duct tape, I was able to secure and seal the filter into place, then I put the grate back on. (A 16x16x1 inch filter would have fit, too, but I would have had to remove the louvers on the vent before taping on the filter.)

air filter

I didn’t notice any reduction of air flow and the room is still under positive pressure. So I’m not concerned with straining the HVAC system of the building.

I hope that it will help keep down the dust in the scope room! I’ll check it in a few months and update.

UPDATE (1/17/17):

I’ve changed the filter twice since August. Here’s a side-by-side of the new filter and filter that’s been installed for a few months. I think it’s working:

demoing the Photometrics Prime 95B back-thinned CMOS

August 1, 2016 at 4:10 pm | | hardware, review

(See my second post on this camera here.)

Photometrics has released the Prime 95B, the first scientific CMOS camera with a back-thinned sensor. This means that the sensor is significantly more sensitive than the front-illuminated versions of other CMOS scientific cameras. So the Prime 95B has a 95% quantum efficiency, whereas other scientific CMOS cameras have 60-70% QE; the newest version of competing CMOS cameras tout 80%+ QE. Back-thinning really helped CCD technology (EMCCDs are back-thinned, for example), but back-thinning CMOS sensors has been more challenging, for some technical reasons that I don’t know.

I demoed the Prime 95B when it was in the Nikon Imaging Center (Kurt wrote up details here). The CMOS camera was installed on a spinning disk confocal along with a 1024×1024 pixel EMCCD. The Prime 95B has 11 um pixels, slightly smaller than the 13 um of the EMCCD’s pixels; this results in a higher spatial sampling rate and thus lower sensitivity for the CMOS, because the photons are spread across more pixels. This can be simply corrected by using a different lens, but we didn’t do that here. So it provided an unlevel playing field, favoring the EMCCD.

emccd vs prime bead

Despite that, the Prime 95B matched or outperformed the EMCCD in all the tests we did. The above image compares the EMCCD (left) with the Prime 95B (right) imaging a 100 nm Tetraspeck bead. Below, I compare them imaging a fixed test sample at very low light levels.

emccd prime

The comparisons I made were mainly qualitative. By eye, I was not able to find conditions were the EMCCD outperformed the Prime 95B. That’s saying a lot, especially because the Prime 95B costs approximately half as much! For single-molecule imaging, the EMCCD might still be the king (see Kurt’s curve), but I didn’t have time to perform those detailed or quantitative tests. But for all other imaging and spinning disk confocal, I’d rather have the Prime 95B. No more deciding the optimal EM gain settings and the large dynamic range of the CMOS make it a real winner!

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