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5 Steps to Perfect Image Engravings

Getting an image to engrave well is a task that often stumps even experienced laser-folk. Often images appear too dark, too light, or "muddy" and lacking detail. 

There are many settings that influence the quality of an engraved image, and each one needs to be refined for the overall image to engrave well. In this article we briefly explain the purpose of these settings and, more importantly, how to get them perfect. 

Steps:

1. Focal Length

Focal Length Diagram

Diagram of the effect of focal length on image engravings

Focal length affects the strength and size of the laser dot where it meets the material. A laser that is perfectly focused will have the smallest dot possible, with the highest strength of the beam.

To find the correct focal length for your hardware, use Laser Tools → Focus Test, if your machine has a motorized Z Axis.

For lasers without a motorized Z Axis, use the method of focusing described by your machine’s manufacturer.

Tip

Some people prefer the look of a slightly defocused laser for engraving, as it softens the edges between scan lines. However, adjusting settings is easiest with a focused laser. We recommend keeping the laser focused while conducting the following steps, and playing with defocusing as an optional step at the end.

2. Speed & Power

Speed & Power Diagram

Relationship between speed and power in laser engraving

The Speed and Power settings affect the depth and darkness of an engraving.

Go to Laser Tools → Material Test to test varying Speed and Power settings, and find a value that engraves nice and dark but doesn’t cut too deep. Dark engravings are generally more difficult with CO2 lasers than diode lasers — CO2 users will typically have more success with slow speeds and low power.

Apply the optimal Speed and Power values you identified to a layer set to Image Mode in the Cut Settings Editor, or save them to an entry in the Material Library.

3. Line Interval/DPI

Line Interval Diagram

Ideal settings for Line Interval/DPI

Line Interval and DPI are tied together. They change the distance between each pass (scan) of the laser head. If Line Interval is too low (and DPI too high), images will be very dark (as the lines overlap). Too high and the image will be too light.

Use Laser Tools → Material Test to find the ideal interval. You’re looking for the value that creates lines that just touch (don’t overlap, nor have a gap). Try values between 120 and 300 dpi (0.08-0.2 mm). You will need a microscope or strong magnifying glass.

If you don’t wish to use the Interval Test, or you are having trouble seeing the overlap of lines on your material, try engraving a gradient and manually varying the Line Interval in the Cut Settings Editor.

When you have found an ideal Line Interval setting, apply it to a layer set to Image Mode in the Cut Settings Editor, or save it to an entry in the Material Library.

Tip

  • When working with material with a grain (e.g wood), orient the test so the scan lines are perpendicular to the grain — parallel makes it difficult to distinguish between engraving texture and material texture.
  • A raking light can help to differentiate scan lines.
  • For best results, create future images with the same DPI as dictated by the Line Interval you found in this step.

4. Dot Correction

Dot Correction Diagram

Diagram showing different levels of Dot Correction

Beams have a thickness which makes dots longer than they should be — we can correct that with Dot Width Correction. Make sure you adjust your settings in Cut Settings Editor as described below:

Additional information on these settings

Using a smoother/more organic image mode (e.g. Jarvis) would not produce this consistent pattern. Bidirectional scanning can result in every other layer being slightly offset, unless you've already perfected your Scanning Offset Adjustment table. This doesn't matter for the more organic image modes, but it's very visible in Ordered.

Ordered Image Mode on a 50% gray rectangle should produce a checkerboard pattern that is 50% engraved and 50% not. Test out the same image with different Dot Width Correction values — the number should always be smaller than whatever you’re using as your Line Interval setting. The valid range is from 0 to your interval value.

Tip

Use Convert to Bitmap to create a 50% gray rectangle.

Once you have found the optimal Dot Width Correction value, apply it to a layer set to Image Mode in the Cut Settings Editor, or save it to an entry in the Material Library.

Make sure to switch back to Jarvis Image Mode, and turn Bi-directional scanning back on (it’s a lot quicker).

5. Adjust Image

Try engraving your image. If you are still not getting the look you desire, it's likely because the image you're using needs some adjusting, which you can do using the Adjust Image tool. Try changing the Brightness, Contrast, and Gamma, along with the Enhance features.

For more help using LightBurn, please visit our forum to talk with LightBurn staff and users, or email support.