Mounted ZnSe Lenses, 50mm and 2.0″ Diameter
ZnSe lenses of meniscus form and of 50.0mm diameter are called ’19.7ZLF’ series. Similar lenses
of 2.0″ (50.8mm) diameter are ’20ZLF’ series. Both sizes have 3.5mm edge thickness and are suitable
for use up to 4 Bar gas pressure.
A limited range of lenses, having 9.6mm edge thickness, are available at these diameters for use at
high gas pressures, but these lenses are not, in general, required in Umicore Laser Optics mounts.
The mount for both diameters is designated ‘M20’; for 50mm diameter the mount is M20A, for
50.8mm diameter, M20B. The external dimensions and threads are identical.
Mounted 19.7ZLF lenses become ’19.7MZLF’ type.
Mounted 20ZLF lenses become ’20MZLF’ type.
Technical specifications, M20 mount
Material : Aluminium HE30
Finish : Black anodised
Identification : None
Thread : 2.5″ dia x 12TPI UNF 2A x 16mm long
Max. diameter : 75.0mm
Overall length : 26.0mm
Clear aperture : 47.0mm
Dimensions : See fig. 8.32
All mechanical dimensions are toleranced to +/-0.1mm, except the mounting thread.
The mount thread is deliberately made to be a slightly loose fit into a female thread of (full)
2.5″ dia x 12TPI.
(Users making a female thread to be a smooth or tight fit to an example lens cell run the risk of
subsequent failure-to-fit with lens cells from other suppliers, or due to batch-to-batch variations).
The mounting method for is shown in fig. 8.31. Indium wire is used for standard ‘ZLF’ lenses. If the
mounting of a high gas pressure lens is required then an ‘O’ ring will be used (see data sections 8.10,
See figure 8.32 and table 8.33. The numerical designation of the lens represents the FL in mm.
Example: 19.7MZLF200 has 200mm focal length.
The M20 mount fits directly to the following
WMD water cooling mount (sections 9.80)
CFF50 focus mechanism
‘LNA’ nozzles are compatible with 50mm
and 2.0″ diameter mounted lenses. See section
LNA nozzles do not attatch directly to the
M20 mount, but interface via model WMD
water-cooling mount (section 9.80)
Product CFF50 can be supplied to accept the
M20 cell and the LNA nozzle without requiring
the WMD interface as a separate item.
Under normal circumstances lenses of this
diameter will be used at high powers, and use
of the WMD water cooling mount is therefore