Two-Photon Polymerization (2PP) Calibration & Process Map

Purpose & scope. This section guides a quick and a full calibration for 2PP with 3Dresyns resins: defining a robust operating window, documenting resolution, and dimensional accuracy at each condition.

Equipment & critical parameters

  • Objective NA and working distance; wavelength (λ) and exposure path.
  • Laser power at sample (mW), repetition rate (frep), pulse width.
  • Writing/scan speed (µm/s), slicing/hatching, layer spacing (∆z).
  • Resin ID, batch, temperature; cleaning and post-cure method.

Quick calibration (Curing Rate Table)

Use when time is limited. Fix your target writing speed and sweep laser power at the sample to populate a Curing Rate Table (e.g., cured thickness/feature continuity vs. power).

  • Objective: determine the optimum laser power at your chosen writing speed for the selected resin and your printer’s specifications.
  • Outcome: by analyzing the table, the power/intensity threshold and the dynamic exposure range can be readily identified.
  • Record: qualitative result (under/optimal/over), minimum continuous line, dimensional error (%), surface quality.

Note. If you can, follow up with the full matrix below to validate limits and expand the process window.

Full calibration (Power–Speed matrix)

Note: To obtain a full calibration, measure responses for (i) laser power at fixed writing/scan speeds and (ii) writing/scan speed at fixed laser powers. The resulting power–speed table delineates the minimum and maximum viable writing/scan speeds per power level and records resolution and dimensional accuracy for each calibration point.

  1. Design the grid. Select 5–8 power levels and 5–8 writing speeds covering your expected range.
  2. Acquire data. Print standardized test features (lines, lattices, pillars) at each grid point with consistent focus and environment.
  3. Measure. For each point, document:
    • Continuity (passes/fails), minimum resolvable line (µm).
    • Dimensional accuracy (% error vs. CAD) and edge fidelity.
    • Surface/ridge quality (qualitative score), defects (burn/voids).
  4. Interpretation. Compute a simple dose proxy P/v (nJ/µm). Map “under → optimal → over” to identify the stable operating window.
Reporting checklist (recommended):
  • Objective (NA), λ, resin ID & batch, temperature.
  • Power at sample (mW), frep, pulse width (if available).
  • Writing speed (µm/s), slicing/hatching, ∆z.
  • Cleaning/post-cure method and times.
  • Resolution (µm) and dimensional accuracy (%) at each grid point.

Glossary — Writing vs. Scan speed

Writing speed: effective speed while exposing (laser ON) along the toolpath; use this value for P/v and pulse spacing: Δx = vwrite / frep.

Scan speed: motion speed of galvos/stages (may include non-exposing moves, jumps, acceleration ramps). Report writing speed for calibration.

Acceptance guidelines (suggested, adapt to application)

  • Dimensional accuracy: ≤ ±2–3% at target feature sizes (50–200 µm typical for process sign-off).
  • Resolution: minimum continuous line meets application spec; no scorching or voids.
  • Stability: ≥ 3 consecutive prints within tolerance at the selected recipe.

Safety & process notes

  • Follow laser safety practices for your system class; use appropriate enclosures and PPE.
  • Use only approved cleaners and post-cure conditions for the selected 2PP resin.

For general guidance, see: Instructions for Use "IFU" for 2PP printers