Laser Focus Test: Ramp Test Generator (Free) · CutCatVector

Free tool · no sign-up · no Z axis needed

Laser focus test

Burn one line along a tilted strip. Where the line is thinnest, the beam is in focus. The number printed there tells you how much to move the laser head.

Your laser

Laser type
W

Optical output power, as printed on the laser module or tube. It sets a starting line power and speed; check them in Advanced settings.

Your ramp

Any straight scrap strip. Measure the block with calipers: a few stacked sheets of plywood work well.

Illustration only. The real line gets thinner where the beam is in focus.

Step 1 · strip, cut flat
Step 2 · test, on the ramp Free, no email needed.
  1. Prop the strip up as in the side view: one end on the bed, the other end on the block. The strip has no marks yet: the LOW end of the design must be over the end on the bed. If you rotate the job, keep that match, not left and right.
  2. Frame shows the design, not the strip: the design is a little shorter (about 1 mm in from each end). Centre the frame along the strip, do not line its edge up with the strip edge.
  3. Focus the laser on the strip at the middle, where the arrow says FOCUS.
  4. Run it. LightBurn: File › Open (not Import). SVG: set every colour to Line mode, power and speed as in the table below.

Read your test

Look at the line under good light, or with a magnifier. Find the thinnest, sharpest part and pick the number printed under it. Between two numbers? Pick the closer tick. Click the picked mark again to clear it.

Where is the line thinnest?

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What to do

Focus correction Pick a mark Positive numbers are above the point you focused on, negative ones below.

How it works

  1. Enter the length of a straight scrap strip and the height of the block you put under one end.
  2. Download the file, set the strip on the block, focus at the arrow and run it.
  3. Pick the number under the thinnest part of the line. The page tells you how far to move the laser head.

Tips

  • Focus first, then everything else. Run this before the material test and the kerf test.
  • The line should be light. Too much power makes it wide everywhere and hides the focus point.
  • Keep the strip straight and the block right under its end: a bent strip or a block placed further in changes the scale.
  • After the correction, focus your flat work the same way as for the test, then apply it. With a focus spacer, change the spacer itself.
  • This finds the narrowest spot on the surface. For thick material some people focus a little inside it to cut better.

FAQ

Why a tilted strip?

Along the strip the surface slowly rises, so the line passes through the focus point. The thinnest part shows exactly where the beam is narrowest.

Which lasers does it work with?

Lasers where you can prop a strip up and keep the focus fixed while the test runs: most diode and CO₂ machines with a manual focus. Turn autofocus off for the test. LightBurn users open the .lbrn2 file; in other software use the SVG with a line (score) operation for every colour. We have not tested every machine yet.

How accurate is it?

The scale step is 0.5 mm (0.02 in) with the default strip and block. The real accuracy depends on how you set the strip up and how clearly you can see the narrowest spot. A longer strip or a lower block gives a finer scale.

Inches or millimetres?

Switch mm / in next to "Your ramp". In inches the numbers on the strip and the answer are in inches. Laser speed stays in mm/s or mm/min, like in LightBurn.

Do I need to cut the strip?

No. Any straight scrap works. If you want, tick "Cut the strip out first" in Advanced settings: you get a separate step 1 file to cut the strip flat with your own cut settings, then you run the test on the ramp.