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.
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