Varax50 Series (Variable Ring-Focus Lenses)


Introductionvariable ring focus
The Varax50 series of lenses produce a CO2 laser focus in the form of a ring of highly concentrated laser power. The outer
control allows the diameter of the ring focus to be varied from a maximum selected value (depending on lens model) down
to about 55% of the maximum diameter.
The standard range contain designs for maximum ring diameters of 0.2mm up to 1.0mm.
Varax50 lenses are based on the use of the proven ‘TF50’ aberration-corrected focusing lens (doublet) with a moving
axicon component. The Varax50 is therefore a 3-element system.
Technical specifications, optical / mechanical
Dimensions : See Figure 25.41.
Construction : Aluminium alloy, black.
ZnSe optics, AR/AR coated for 10.6μm.
Copper nozzle tip.
Clear aperture : 25.0 mm diameter.
Cooling : Air cooled, or use WMA mount.
Fittings : 1.5″ x 12TPI UNF (as for M11 cell).
Max CW power : 2000W CW, assumes use of WMA mount.
Calibration : Scale engraved at 10° intervals, where 140° is full movement.
Method of operation : Actuation of the control ring moves an axicon component axially, changing the diameter
of the ring focus. An actuated linear slide method is used to eliminate lateral focus
movement during operation.
Assist gas : Via 6/4 fitting.
Gas nozzle : Built-in. Nozzle tip diameter is 2.0mm.
Standoff : User adjustable in range 1 to 5mm.
Focus control : None, needs external z-axis control.

ring focus lens

Applications notes

Variable axicon systems find their main use in drilling of materials, especially plastics of various types. The ‘zoom’ control
of ring diameter is useful when the laser operator needs to have fine-control over the diameter of the drilled hole.
Application warning
The processing properties of materials will differ in each case. Note that the Varax50 specification refers to the ring
diameter of the peak of the energy distribution. Some plastics may ‘melt-back’, or respond to the lower energy ‘tails’
outside the ring peak. Other materials may respond only to peak energy (depending on process speed).
In general, it may not be possible to predict the ideal model of Varax lens without preliminary applications trials.
Associated equipment
Varax50 models fit direct to any system which will accept an M11 lens cell (the standard mount for 1.1″ ZnSe lenses).
Compatible Umicore Laser Optics equipment includes:
WMA mount ….. section 20.3.
FF25 fine-focus unit ….. section 63.1.
CFF25 coarse/fine focus unit ….. section 63.2.
LAU25 lateral adjustment unit ….. section 72.1.
LAM25 lateral adjustment unit ….. section 72.2
Nozzle tip
Model Varax50 has a low-cost, easily replaceable, copper nozzle tip.