CO2 Laser Focus Lens: What you need to know

A CO2 laser focus lens is a vital part of most every laser cutter and engraver. Whether you are a hobbyist, enthusiast, or a business professional, determining the right lens for your needs can be confusing at first. Unfortunately, there is no single lens that will work for every project, but you can change out your lenses to match your specific needs and make sure you get the best results out of your CO2 laser engraver.

Each lens has different capabilities depending on whether you are using it to cut (vector) or just engrave (raster). The variables will range anywhere from the thickness or hardness of your material, to the level of detail that you need to cut or engrave. Let’s take a look at different lens options to help you get the laser focus lens that you need.

CO2 Laser Focus Lens: How it works

When the laser beam is emitted from the laser tube, it fires in an unfocused state. Since the beam that is fired from the CO2 laser tube is wider than that of the fiber laser or UV laser, it will need to be focused to a point where it can interact properly with the material. The laser beam will still be able to mark on your materials without a CO2 laser focus lens, but it will appear as just an inconsistent burn mark.

In order for the beam fired from the CO2 laser tube to be usable, it needs to be focused to a point at a specified distance via a convex lens. The focal point of these lenses range from one and a half inches to five inches away from the lens, and that distance will determine how the laser beam affects the material.

To put this into layperson terms:

• The shorter focal lengths will be able to engrave smaller details but will lose cutting depth,
• The longer focal lengths won’t be able to engrave as fine of details, but will have an increased focal length

CO2 Laser Focus Lens: Air Cones

The different focal lengths of the lenses range from 1.5” to 5” and will come with the proper tools and air cones that will be needed for that lens to focus and function properly.

On the Muse series CO2 lasers, there will be a different nose cone that will be used for each focus lens. This nose cone will deliver the optimal psi from the air assist onto your material to help blow any dust or debris out of the way and help prevent flame-ups.

For the P-Series high production laser systems, there will be two different cone lengths that will be used. A larger air cone will be used for the lenses with the longer focal lengths, and the short cone will be used for the lenses with the shorter focal distances.

CO2 Laser Focus Lens:  Focal Length Breakdown

The four different focal lengths that are offered are the 1.5”, 2”, 2.5” and 5” options. The Muse Series comes standard with the 2” lens and its associated air-cone preinstalled, and the P-Series comes standard with the 2.5” lens and the appropriate air-cone preinstalled.

• 1.5” Focus Lens (0.003” spot size): This is the lens with the shortest focal length. Because the beam will focus more closely to your material, this means that it will also spread after the focus point more quickly. Because of this, the beam is focused to a much smaller point which will allow you to engrave details as small as 6pts, but due to the quick spread of the beam, it is not good for cutting. It is best used for fine details and thin lines.
• 2” Focus Lens (0.004” spot size): Included with the Muse Series CO2 lasers, this lens will be able to engrave fine details, but the beam still spreads fairly quickly after the focal point. It is best used for fine details and cutting thin materials.
• 2.5” Focus Lens (0.005” spot size): This is the lens that comes standard with the P-Series laser systems. While it can’t engrave as fine of details as the smaller lenses, it can still engrave fonts as small as 8pths. The laser beam does not spread as quickly, making it great for cutting materials up to a half inch thick. It is best used for normal engraving and cutting materials up to 0.5”.
• 5” Focus Lens (0.01” spot size): Since the focal length is twice as far as the previous option, this prevents the beam from spreading too quickly beyond the focal point, allowing for cutting thicker, soft materials like foam. Since the spot size is larger, this prevents it from cutting harder materials like wood and acrylic. It’s also a great option for engraving into deep objects like bowls and boxes, and is required for using the passthrough on the Riser attachment for the Muse Core and 3D laser systems. It is best used for engraving on irregular/deep objects and cutting thicker, non-dense materials.

Different focal lenses will produce different results. Make sure you have the right lens for the job.

Every CO2 laser focus lens will have a different application. Having the ability to swap out your focus lens to accommodate different projects and materials is one of the many ways that you are in control of what you can create. This opens up your possibilities, and it means you aren’t limited to a single focal length and material width.

If you are unsure what lens you will need, either for your new laser you are about to purchase, or for a laser system that you already own, Full Spectrum Laser has technical experts who are able to assist you with making the right choice.

Full Spectrum Laser is a leader in easy to use, highly versatile laser cutting and laser engraving machines. Our systems range in size from desktop units and high-volume machines through industrial-grade production equipment. Our machines are running all over the world: from grade schools to National Labs, garage startups and many Fortune 500 companies. Contact us today to learn more.