Color Delay Explained
Why laser strokes start dark or draw faint lines between shapes, what the Color delay control does about it, and how to dial it in on your projector.
A projector's mirrors and its color channels do not switch at the same instant. The mirrors are physical — they have mass, and they lag. The lasers switch almost instantly. So by the time the beam has actually arrived somewhere, the color it was told to draw there may already have come and gone.
Color delay fixes that by holding color back to meet the mirrors.
How to tell you need it
Two visible symptoms can indicate a timing mismatch. They can also have other causes, so follow your projector manufacturer’s setup guidance.
Faint lines between your shapes
You draw two separate shapes and a dim line connects them. The beam was supposed to be dark while travelling between them, but color was still switching off as the mirrors began to move — so the tail end of a stroke gets smeared across the gap.
This is the more common and more obvious one. Most people notice it as "my letters are joined up" or "there's a ghost line across the image."
Strokes that begin invisible
The opposite case. The mirrors arrive, but color has not caught up, so the first fraction of every stroke scans dark. Letters lose the start of each pen stroke, circles look like they have a bite taken out, and fine detail thins out unevenly.
Dialing it in
Use one shape with clear separations — a word works well, since missing stroke starts are obvious in letterforms.
- Start at the default. +120 µs is the starting value. Adjust it for your projector and point rate; it is not a calibration guarantee.
- Change the value by one 10 µs step and compare the start and end of each stroke.
- If the result gets worse, return to the previous value and try the other direction. Do not assume a missing stroke always calls for a larger delay.
- Stop when the transitions look clean. If neither direction helps, restore the previous setting and check the rest of your projector setup.
Change one thing at a time. Point rate and color delay both affect how strokes begin and end, so adjusting them together makes it very hard to tell which one helped.
Positive and negative values
Positive values delay color relative to the scanned position; negative values shift the timing in the opposite direction. Choose the value that aligns the visible stroke starts and ends on your projector.
Available range
The control offers −300 to +300 µs. If that range cannot produce a clean result, check your projector setup and follow its manufacturer’s calibration instructions. Recheck the result after changing the point rate or projection size.
It is remembered for the connected DAC
BeamTracer remembers the setting for the connected DAC in this browser when site storage is available. If you attach a different projector to the same DAC, recheck its calibration. Clearing site data or using a different browser can restore the default.
Laser DAC Output
Where the Color delay control lives, plus everything else about driving real hardware.
Blanking Explained
How the beam travels between shapes without drawing — the dark gap color delay has to fit inside.
Understanding PPS
Point rate, and why it changes how much delay you can usefully apply.