This demo is a complete measurement, done the way a lab does it: two instruments driven from one window, ending in an analysed result and a report — first on one PC, then, if you have a second one, across two as in a lab. No instrument is attached. Everything else — the software, the plan, the analysis — is exactly what runs in the lab.
The window is PLESTY Bench, the application that goes on each lab PC. It installs the software for an instrument, starts it, and runs measurements. A PC running it is called a bench.
First: install PLESTY Bench
Download the installer for your system from the Download page and run it. That is all the demo needs installed by hand: the bench fetches everything else itself. For the two-PC version, install it on both.
Then run the demo one of two ways:
The first start of PLESTY Bench 0.5.0 offers to install the demo and run it: one button, about a minute. Across Two PCs
The stage on one bench, the spectrometer on another, one window driving both — as a lab runs it.
What is measured
A quantum dot is a nanoscale light source: excite it with a laser and it emits light at a few sharp wavelengths, its emission lines. Some of those lines are really two lines very close together, each polarised in its own direction. The gap between them is the fine-structure splitting, a few micro-electronvolts, and measuring it is what this experiment is for.
To see it, the emitted light passes through a half-wave plate — an optic that rotates the polarisation of light as it turns — in front of a fixed polariser. The plate is turned in 2° steps, a spectrum is taken at every angle, and a line that is really two lines shifts back and forth as the angle changes. The size of that swing is the splitting.
The experiment is plesty-pol-pl, for polarisation-resolved photoluminescence.
Where the data comes from
Two instruments take part, and each has a device module: a Python package that knows how to talk to that one instrument, and that runs as a small server other software reaches over the network.
| Instrument | Module | In the demo | |
|---|---|---|---|
hwp |
Half-wave plate on a Thorlabs K10CR1 rotation stage | plesty-k10cr1 |
Its built-in simulator, which homes and moves like the real stage |
spec |
Princeton Instruments spectrometer, driven through LightField | plesty-lightfield-spectrometer |
Its demo/pol-pl version, which answers with spectra really measured on sample E098-SIL, quantum dot QD-002 |
So the numbers the demo produces are the numbers the lab measured. The experiment cannot tell the difference, and neither can the analysis.
The result
Run on one PC or on two, the analysis finds the same. QD-002 has four emission lines. Two swing with the angle — each is a pair — and two stay flat:
| Line | Splitting | Polarisation axis |
|---|---|---|
| 778.140 nm | 11.52 ± 0.13 µeV | 72.8° |
| 780.143 nm | 11.42 ± 0.21 µeV | 27.7° |
| 780.068 nm, 780.581 nm | not resolved (below 3 standard errors) | — |
Every run ends with report.html in its folder, and Export HTML in the Report pane saves a copy anywhere. It is one file that opens in any browser, and it holds the whole run: what was run and how it ended, where each instrument ran, the settings the run used, what the analysis found, and every raw record.
Next
- Build your own: Build & Run a Device takes one instrument from the hub or from nothing to a running server on a bench; Build & Run an Experiment builds a measurement on top of it, down to its analysis and live view.
- How it is wired together: Networking and Data Flow.
- With your own instruments: Run an experiment in the bench documentation explains each step of a run in full.