[time-nuts] 88Sr+ ion-clock live stream

[Anders Wallin]

Hi Jim, yes you are right  the background is a camera-image (about 30x
magnification, maybe 1um per pixel). We use a microscope-objective, a
narrow 422nm bandpass filter, then an image-intensifier, and a fairly
standard CCD camera that looks at the output of the intensifier. When
everything is working and optimized I think a good quality (high QE) CMOS
or CCD camera alone could work. I think it would be interesting to try e.g.
a budget camera made for astrophotography at some point.
If you have lots of money then an EMCCD camera (30-50k maybe) is a good
solution.

The camera is only used for observation and coarse diagnosis of major
problems. For quantitative measurements we have a beam-splitter that
directs most of the fluorescence towards a pinhole followed by a PMT
photon-counter. The ARTIQ controller can time-stamp each incoming photon
with 1ns resolution (but this creates a lot of data) - mostly we just bin
the counts into some gate time and look at the time-series of counts per
20ms or so.

The live stream is created with OBS. It captures the camera image as
background and can overlay any images/websites etc. that we can imagine.
I create the Zeeman-spectrum barchart in matplotlib as a PNG image with
transparent background - once per minute, from data we store in InfluxDB.
The X-axis labeling was not so good - need to improve that next time.
Somehow indicate that line-center is 445THz and the peaks really are <1e-12
wide (narrow!).

For the impatient, I made a speedup (128x) version of the live-stream:
https://www.youtube.com/watch?v=f3edhdwqXgc


Anders

On Sat, Dec 7, 2019 at 1:48 AM jimlux <jimlux at earthlink.net> wrote:

>
> > The central bright dot is fluorescence at 422nm from laser cooling a
> single
> > trapped 88Sr+ ion. The ion emits about 1e7 photons/s at most and we
> > currently detect about 500 of those in a 20ms detection window (using a
> > Hamamatsu PMT module).
>
> Very cool. A question about the display - it's a video image of the
> fluorescence, and the graph is superimposed on top of it?
>
>