Five checks that make the clinic modules (Pop Motion, Vision Trainer, Drive, Flight) show stimuli at the intended size, speed, contrast and rate on this screen. The result is saved on this device and read by every module; re-run it when the screen, distance or browser changes. Nothing here flashes.
1Screen scale not done
Hold a bank card against the screen and drag the slider until the dashed box is exactly the size of the card (85.6 × 54 mm). This tells us how many pixels make a millimetre.
2Viewing distance not done
Measure from the viewer's eyes to the screen. Clinic modules convert degrees of visual angle to pixels with this.
3Refresh rate & frame timing not done
Measures how many frames per second this browser actually delivers and how steady they are. Reversal rates are only clean when a half-cycle is a whole number of frames.
4Greyscale & contrast not done
You should see eleven distinct steps from black to white. Then drag the slider until the grey square matches the brightness of the fine checkerboard beside it (squint or step back); that estimates the screen's gamma.
5Red / cyan glasses not done
Only needed for the dichoptic modules. Put the glasses on: through the red lens the cyan word should vanish and the red word stay; through the cyan lens the opposite.
✓Result incomplete
Modules read the saved profile automatically and show "Calibrated" in their status line. Profiles expire after 30 days as a reminder to re-check.