# Physical Devices

Build and setup guides for the physical instruments used at a PQN Node.

A Node's software (`pqn-node`, `pqn-hardware`) drives a stack of real optical and electronic hardware: polarimeters, time taggers, polarisation rotators, lasers, and the optomechanics that hold them in place. This section collects the hands-on guides needed to build, wire, and prepare those devices for use.

The first device documented here is the **polarimeter**, the tactile centrepiece of a PQN Node, designed to be 3D-printed cheaply enough that any institution can build one. Other devices (TimeTagger setup, rotator wiring, alignment procedures) will be added as standalone subsections over time.

```{toctree}
:maxdepth: 2

polarimeter/index
```