Using different lenses
Selecting the right lens can be the key to perfect laser results. Use the following guide to determine which lens you should use for your application.
Trotec CO2 laser machines generally work with lenses in the range of 1.5" to 4" The distinctive feature is the distance between the lens and focal point of the laser beam.
While 4" is almost entirely used for cutting of thicker materials, 1.5" to 2.5" lenses are mostly used for combined engraving and cutting applications.
As a general rule, smaller focal lenses (1.5") are preferable for very fine details, while larger focal length lenses (2" / 2,5") will simplify the engraving on most laminates and result in a smoother engraving outcome.
A lens with shorter focal distance, e.g., 1.5", will produce a small laser spot at the focal point, which allows for very fine detail engraving and high concentration of laser power.
A side effect is that engraving lines might be noticeable when engraving larger areas, as the spot is small and engraving lines are not overlapping. This can result in a somewhat rougher surface of the engraved material, with colors being less lucent. Increasing the z-offset will help to reduce this effect by moving out of the focal point and thereby widening the laser spot.
When working with materials that are sensitive to temperature (e.g., plastics), a larger spot will induce less heat. It will, therefore, reduce the possible effect of warping during the engraving of large areas.
| Lens | Application areas for engraving / marking | Application areas for cutting |
|---|---|---|
| 1.5 inch CO2 | Graphics with fine details, (> 500 dpi resolution), stamps with thin letters |
Low laser power levels, thin materials (e.g. paper), acrylic < 6 mm, wood of medium hardness < 8 mm |
| 2.0 inch CO2 | Graphics with medium details and resolution (500 dpi; with reduced sharpness to 100 dpi resolution), standard engravings |
Medium laser power level, acrylic < 8 mm, wood of medium hardness < 12 mm |
| 2.0 inch CO2 clearance lens | Mainly used for cutting | See 2.0 inch lens. Increases the distance between laser head and material. Is especially useful if the increased distance is required due to the material and the graphic |
| 2.5 inch CO2 |
Graphics with less details, low resolution (< 500 dpi). Engravings on heat-sensitive materials (e.g. laminates), if large areas have to be removed completely. |
High laser power levels, acrylic < 12 mm, wood of medium hardness < 15 mm Better quality of edges during laser cutting than for lower focal distances. |
| 2.5 inch CO2 clearance lens |
Used exclusively for cutting | See 2.5 inch lens Increases the distance between laser head and material. Especially useful if the increased distance is required due to the material and the graphic. |
| 2.85 inch flexx | Standard lens for the Speedy flexx series. Permeable both for CO2 lasers as well as fiber lasers. Both laser sources can be used without changing the lens. Other characteristics as for the 2.5 inch CO2 lens and the 3.2 inch fiber lens |
Characteristicsas for 2.5 inch CO2 lens and 3.2 inch fiber lens |
| 3.2 inch fiber | Standard lens for fiber lasers with an extremely small focal diameter. Graphics with fine details (> 500 dpi resolution) | |
| 3.75 inch CO2 circular engraving |
Special lens for SP500 rotary attachment Allows processing of circular engraving objects that are less than 50 mm in diameter. |
This lens is not used for laser cutting |
| 4.0 inch CO2 | Engraving by burning of wood, laser engraving of graphics with low detail with high laser powers | Foam rubber |
| 5.0 inch CO2 | Is not used for laser engraving | High laser power, acrylic < 25 mm, wood of medium hardness < 20 mm Better quality of edges during laser cutting than for smaller focal distances |
| 5.0 inch fiber | Lens for fiber lasers if materials that are not absolutely plane are to be labeled. The greater focal distance results in a greater tolerance during focusing. | |
| 7.5 inch CO2 (for SP1500) | Is not used for laser engraving | High laser power, acrylic < 40 mm. Better quality of edges during laser cutting than for smaller focal distances |
Please note that not every lens is available for each device. We will be happy to assist you in selecting the ideal lens.