Not all laser cutting projects are made on perfect, flat pieces of material. Some applications might have uneven surfaces, such as this ukulele. When a design comes out of focus range, the output will become blurred, distorted and/or faded. If this is the case, it is easy to be confused on how to focus the laser for the best output for the uneven surface.
To help correct this, with a 2.0” focal lens, the laser can be out of focus up to 1/8 of an inch either way and still achieve a good raster engraving.
Splitting the Difference
For the best results you will have to split the difference between the highest point and the lowest point of your piece. Using a standard 2.0” focus lens, you have a depth of field of a 1/4 inch to achieve your raster on a uneven surfaces with a hobby laser. This means you have 1/8th of an inch below and above the focus point. Note that focus lenses can vary in length and each will have a different depth of effective focus.
Breaking Up Uneven Surfaces
Some designs will have to be broken up into separate files. If a given project has two different heights that are outside of 1/8 of an inches of difference, then you will have to break up your design into multiple files and focus and cut each separately.
To learn more, download our free ebook, Designing for Laser Cutting: A Technical Ebook for Creatives, where you will discover more design tips such as:
- Choosing Image Files
- Raster Engraving Techniques
- Designing for Vector Cuts
- Utilizing Kerf in Design
- 3D Object Stacking Designs
- And dozens of other tips & techniques
And look for more ebooks, coming soon, from Full Spectrum Laser.