Changing laser lenses enables you to shape your engraver's laser beam according to certain properties, making it easy to improve engraving or cutting quality, or even productivity. This guide explains the effects of different lenses on your laser beam and helps you determine which lens is the best answer to your application.

What Is a Laser Lens?

The laser lens is the optical element of your machine that focuses the laser beam. The laser beam is between 8 and 10 mm in diameter before the lens. The lens concentrates the beam at a thin point for greater precision and more concentrated power. This point is called the focal point.

Choosing a focal length defines the diameter of the laser spot and therefore the width of the engraving line. The focal length also defines the focus depth -- the distance over which the beam is considered to be focused. The depth of field is used to define the acceptable difference in flatness on a part for uniform engraving.

The Three Main Laser Lenses

Lens 1.5" -- Precision and Sharpness

The 1.5-inch lens delivers the smallest spot diameter (0.06 mm) with a focus depth of 0.5 mm and a focal length of 37.5 mm. It is perfect for:

It is not suitable for cutting thick materials (greater than 3 mm) or engraving large areas.

Lens 2.0" -- Multi-Purpose

The 2.0-inch lens has a spot diameter of 0.08 mm, a focus depth of 0.8 mm, and a focal length of 50.0 mm. It is perfect for:

It is not suitable for precision engraving or cutting of thick materials (greater than 8 mm).

Lens 4.0" -- Thick Cutting and Fast Engraving

The 4.0-inch lens has a spot diameter of 0.16 mm, a focus depth of 3.3 mm, and a focal length of 100 mm. It is perfect for:

Its disadvantage is low resolution engraving and wide cutting lines.

Engraving and Cutting Comparison

In practical comparative tests on ultra-detailed wood engraving and 10 mm acrylic cutting:

Focal Lengths Available for Your Machine

Different focal lengths are available depending on your machine model. Gravotech offers lenses in 1.5", 2.0", 2.5", 3.0", 3.5", and 4.0" sizes for various machines:

Green references in the Gravotech catalog indicate the lenses supplied with the machine by default.

How to Calibrate Your Machine to a New Lens

Follow these steps to change your laser lens and recalibrate your machine:

  1. Save your actual configuration: Open your driver's interface by opening your machine's printing preferences. In the "Machine" tab, back up your current settings by clicking "Send to computer." Then unscrew the fleece screw, remove your current lens, and attach your new lens in its place.
  2. Change your machine settings: In your machine's menus (X button), select "Configuration," then "Lens," and indicate the focal length of your new lens.
  3. Run the calibration test: Calibrate your machine to its new focal length by launching the calibration job via the driver interface. Prepare a sheet of anodized aluminum and run the job -- the machine will engrave 13 lines.
  4. Select the best calibration: Select the number of the engraved line you feel is best engraved in the "Focus" field of the driver interface. Your machine is now perfectly calibrated to its new focal lens.

Conclusion

Choosing the right laser lens is essential for optimizing engraving quality and cutting performance. For precision work, use a shorter focal length (1.5"). For thick material cutting, use a longer focal length (4.0"). For versatile everyday use, the 2.0" lens is the best all-rounder. If you need help selecting the right lens for your Gravotech laser engraving machine, contact SOFRAY EMS for expert guidance.