14TF Series Aberration Corrected Lenses
The 14TF series lens assemblies use two ZnSe lens elements to correct for spherical aberration and
thereby give diffraction-limited performance. The ZnSe elements are made from laser grade
material polished to a high standard of surface smoothness and coated with ultra-low absorption antireflection
coatings. 14TF series lenses are housed in a M15 cell of the industry standard type for 1.5″
diameter components. All models in the 14TF series have a flat surface nearest the workpiece. This
enables easy rework of the surface which encounters back spattered material and which may require
refurbishment after prolonged use.
Five focal lengths are offered as standard. Full details of the mount and the lens clear working
distance ‘B’ and flange-to-workpiece distance ‘A’ given in Figure 21.11 and Table 21.12 below. All
types have 34mm clear aperture and are capable of use up to 6 bar assist gas pressure.
The principles of the use of aberration-corrected optics are described in full in Technical Data
Section 20.0. For appropriate focal lengths and beam diameters, aberration-corrected lenses allow
higher energy densities to be achieved in comparison with single element meniscus lenses.
After prolonged use, one or more surfaces may suffer from marks due to cleaning and from
backspattered material or laser-burned-in dust particles. Because all surfaces are spherical or flat,
refurbishment is both possible and economical. For details of lens refurbishment see Section 6.0.
The 14TF series lenses are suited for use with model WMB water cooled mount (Section 21.3).
An appropriate size of coarse/fine focusing head is model CFF38, detailed in Section 63.3.
Gas nozzles fitting model WMB mount and appropriate for use with the 14TF lenses are MNA
nozzles described in data section 9.20