CO2 f-theta lens/ Scan lens
STSL scanner lenses specially designed and optimized for use in CO2 laser 2-axis galvo-scanner systems with full beam diameters of up to 15.0mm. Mirror sets appropriate for use with beam diameters up to 15mm require an increase in mirror separation in comparison with smaller mirrors. These changed optical conditions are catered-for by the STSL series. These single-element lenses are designed to represent the best achievable compromise for on-axis and off-axis aberrations, field flatness and F-theta characteristics, obtainable using single-element spherical-surface designs of (standard) 48mm diameter and 3mm edge thickness. The lens material is ZnSe.
PartNumber | FocalLength (mm) | FieldSize (mm) | WorkingDistance (mm) | FocusedBeam Diameter (um) | |
Average | DiffractionLimit | ||||
STSL-10.6-75-50 | 75.2 | 50x50 | 74.17 | 171 | 86 |
STSL-10.6-100-70 | 101.3 | 70x70 | 101.39 | 181 | 116 |
STSL-10.6-150-105 | 149.1 | 105x105 | 150.59 | 219 | 171 |
STSL-10.6-250-175 | 249.4 | 175x175 | 253.26 | 320 | 285 |
STSL-10.6-300-210 | 298 | 210x210 | 302.56 | 373 | 341 |
STSL-10.6-435-300 | 432.7 | 300x300 | 440.97 | 525 | 495 |
Raw materials properties:
Only lasergrade ZnSe is used in the fabrication of lenses.
Tolerances:
Unless otherwise specified by the customer and made to special order, standard tolerance are:
Diameter: +0/-0.1mm
Centre thickness:+/-0.1mm
Centration: ETV ≤0.05mm
Surface form: Spherical within λ/80 at 10.6μm over any 25mm dia test area.
Focal length: Designed and fabricated within 0.5%
Surface roughness: Within 20A ms (usually 12A ms)
Transmission: >99.6% when AR/AR coated for 10.6μm
Coations:
Standard AR/AR coatings are very low absorption, which helps to minimize thermal lensing effects when used with high intensity laser beams.
Laser damage threshold:
3000W/mm (+/-10%) This is equivalent to 228km/cm2 at 5kw laser power (measured result)
Mechanical stress, and contamination/backspatter all reduce the CW LIDT. Poorly designed nounting arrangements combined with over-tightening of clamp rings can reduce the LIDT to 100w/mm
Thermal lensing:
CO2 laser lenses exhibit thermal lensing at sufficiently high beams intensities. Thermal lensing is kept to a minium by the use of lasergrade ZnSe, smooth polished finish and low absorption coatings.
Lens thickness:
Lenses have two thickness: the centre thickness CT and the edge thickness ET. Centre thickness is relevant to the lens design and focal length. Edge thickness is relevant to maximum assist gas pressures, and mounting arrangements.
