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How to open and reconfigure a cube

Task-oriented. You need an empty cube, a rotated mirror, or a flipped lens.

Every UC2 cube consists of two halves holding a sliding insert that carries the optics (lens, mirror, sample holder…). Because the halves come apart, one cube can play any role.

You'll typically do this when:

  • a build needs an empty cube as a spacer (e.g. the Kepler telescope),
  • a mirror or lens must be rotated 90° (e.g. the eyepiece looking upward),
  • a lens must be flipped so its curved side faces the right way,
  • you want to see how the system works inside — which is the whole point of UC2.

Steps​

  1. Hold the lower half of the cube and pull the upper half straight up. No tools needed for the standard cubes.
  2. Slide the insert out sideways along its rails. Don't force it; if it sticks, wiggle gently.
  3. Do what you came for: rotate the insert 90°, flip it, swap it for another one, or leave the cube empty.
  4. Slide the insert back in until it seats fully, and press the upper half back on until the corners click flush.
🖼️ Image placeholder — cube-open-sequence.jpg

TODO (Benedict): a 4-step photo sequence (well-lit, on neutral background): closed cube → halves separated → insert half-way out → insert rotated and re-seated. The old schematic exists in the Didaktikkonzept; real photos beat it.

Getting it right​

  • Check the optical axis: after reassembly the lens/mirror centre must line up with the cube's face openings. A tilted insert shows up immediately as a shifted or smeared image — which is a great error-hunting exercise, but not what you want mid-experiment.

  • Lens orientation matters: for the plano-convex CoreBox lenses the image is sharper when the curved side faces the parallel (collimated) light — towards the distant side. If edge sharpness looks bad, flip the insert.

    ✏️ TODO — Benedict

    Confirm and document the intended orientation of each lens insert (50/100/−50 mm) once, with one labelled macro photo per lens. This directly addresses the feedback that "you can't tell which way round a lens is mounted".

  • Don't over-squeeze. The halves are designed to hold by friction; forcing them can tilt the insert.

Why the tolerance matters (a 30-second detour)​

The insert seats reproducibly to within ~0.1 mm. That's not perfectionism: a lens tilted by a degree or displaced by half a millimetre visibly degrades the image. Professional modular systems (cage systems, Thorlabs-style mounts) fight exactly the same battle with steel rods — UC2 does it with printed rails and magnet/screw kinematics. Letting students feel this tolerance is a feature, not a bug.