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FAQ’s

Fusion Ascent Focus Lenses
Achieving Perfection Through Lens Selection

What Lens do I need?

In laser engraving and cutting, striving for optimal results depends entirely on choosing the right lens. This principle is similar to a photographer selecting different lenses for close-up macro shots versus wide-angle landscapes. The key distinguishing factor among laser lenses is their focal distance, measured in inches.

The key factor is the focal distance, which is the distance from the lens to the point where the laser beam achieves its smallest diameter, known as the focal point. As the beam passes through the lens, it takes on an hourglass shape. The maximum energy density is found at the center of this hourglass; positioning your material surface at this exact point ensures a more concentrated and precise beam.

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1.5″ Lens

  • Extremely small spot size
  • Shallow depth of field
  • Best at detailed engraving
  • Thin material cutting
  • Larger kerf
  • Not ideal for cutting
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2″ Lens

  • Small spot size
  • Optimal depth of field
  • Best all around lens
  • Good for engraving and cutting
  • Best for thick material cutting
  • Broad material range for engraving and cutting
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4″ Lens

  • Larger spot size
  • Long thin beam path
  • Greater clearance from material
  • Best for thick material cutting
  • Smallest kerf
  • Best for engraving on curved surfaces
Related Questions:

Focus Lens Chart

Choosing the Ideal Focus Lens for the Fusion Ascent

Determining the appropriate lens relies on a range of considerations: laser power, material type, graphic detail/resolution (DPI), and material thickness.

The Golden Rule of Thumb: Greater graphic detail warrants a shorter focal distance for laser engraving, while thicker materials in laser cutting require a longer focal distance.

LensEngraving & MarkingCutting
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1.5 inch
CO2
Highest-Resolution Engraving:
Graphics with extremely fine detail (resolutions > 600 DPI). Perfect for very small fonts and delicate vector etching. Produces a tiny spot size (0.003″ to 0.0065″).
Thin Materials:
Good for cutting very thin materials (less than 1/16 inch), such as paper, cardstock, or thin wood veneer.
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2.0 inch
(Standard)
CO2
Standard Multipurpose:
Graphics with medium detail and resolution (300 to 600 DPI). The ideal compromise for general-purpose engraving on most standard items.
Standard Cutting:
Medium-thickness materials. Best for cutting acrylic up to 5/16″ and wood of medium hardness up to 1/2″.
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4.0 inch
CO2
Deep / Recessed Engraving:
Not recommended for fine detail. Used primarily when engraving within a recessed area of a product, such as the inside of a bowl or deep plate.
Thick Materials:
Produces a focused beam over a longer vertical distance. Ideal for cutting thick materials like dense foam, thick wood, and thick acrylic with straighter edges.
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2.0 inch
(Standard)
Fiber
Standard Precision:
fiber laser lens featuring a fine spot size. Optimized for high-precision engraving and versatility.
Not used for cutting.
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5.0 inch
Fiber
Irregular Surfaces:
Fiber lasers only. Designed for metal/plastic products that have a slight curvature or are not perfectly flat.
Not used for cutting.
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FAQ

What is the depth of field (focal tolerance)?

Depth of field denotes the optimal focus range over which the laser beam operates effectively without losing its intensity. Longer focal distances (like the 4.0-inch lens) result in an extended depth of field. Consequently, when cutting thick materials with a 4.0-inch lens, the cut edge appears much straighter compared to using a shorter lens. However, a longer focal distance also means a larger overall beam diameter, which reduces heat per unit area and makes fine engraving difficult.

Can I use the 1.5-inch lens for all my engravings to get better details?
While the 1.5-inch lens provides breathtaking detail for high-resolution graphics, its very short depth of field makes it highly sensitive to focus. If your material is slightly warped or uneven, the beam will quickly lose focus, causing the engraving to blur. It should be reserved specifically for perfectly flat items requiring the utmost precision.
Why is the 2.0-inch lens the standard on the Fusion Ascent?

The 2.0-inch lens offers the perfect middle ground. It provides excellent engraving quality for standard resolutions while still maintaining enough depth of field to easily cut through the most common material thicknesses (like 1/4-inch wood and acrylic). It is the most versatile workhorse for day-to-day operations.

Do I need the 4.0-inch lens if I only cut 1/4-inch wood?
No. The standard 2.0-inch lens handles 1/4-inch wood well. The 4.0-inch lens is an optional upgrade necessary when you start dealing with much thicker stock (e.g., 1/2-inch to 3/4-inch materials) or when you need the physical clearance to drop the laser down into a recessed object.
Do I need a separate lens for the fiber laser if I have a Dual Source machine?
Yes. CO2 and Fiber wavelengths are entirely different, meaning the optics must be tailored to the specific laser source. If your Fusion Ascent is equipped with a fiber laser, utilizing a designated Fiber lens (like the 5.0-inch Fiber) ensures the beam focuses correctly on metals and engineered plastics.
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