BEZ5 Zoom Beam Expander
The BEZ 5 zoom beamexpander has controls for both focus and zoom magnification. It is designed for use
with CO2 lasers having up to 6mm beam diameter and 500W CW power.
Features of model BEZ 5 include:
* Good beam pointing accuracy.
* Focus control from -2M, through to +1M.
* Low beam compression ratio (see Technical Data section 24.00).
Focus control, combined with variable magnification, allows the user of model BEZ 5 to achieve ideal
downstream laser beam conditions from a variety of input beam parameters.
BEZ 5 is designed for use with sealed waveguide lasers such as Synrad, various models.
Dimensions :See figure 24.211.
Weight :1.2 kg (approx).
Cooling :Air cooled.
Focus range :+1.0m, through ‘infinity’ to -2.0m.
Zoom range :x2.5 to x5.0, continuously variable.
Output clear aperture :26mm diameter.
Input clear aperture :14mm, (5.2mm usable at M= x5.0).
Beam compression ratio :0.4:1.
Fitting (input end) :52mm diameter x 1.5mm pitch F/M thread.
Beam wander :<2 arc minutes.
The BEZ 5 is a 3-element design using ZnSe lenses in black-anodised aluminium housings. A ‘negativepositive-
negative’ lens design gives a low beam compression ratio. The two input lenses provide the zoom
magnification and are contolled by means of an external zoom control ring.
Lens (3) is moved axially to provide beam focus control, and this motion is effected by means of an external
The lenses are centred within their internal sub-cells to accuracies of a few arcseconds. The sub-cells move
axially within a precision bore.
The lenses do not rotate during activation of the zoom and focus controls. So, the assembly has a very high
level of inherent centration accuracy, minimizing beam-wander.
The beam-wander of <2 arc minutes (about 0.6 milliradian) is specified for an incident beam aligned to the
optical axis of the BEZ 5.
(1) Establishment of ideal beam conditions for processing in low and medium power CO2 laser systems.
(2) Production of the ideal beam in aperture-limited laser scanner systems.
(3) Special test equipment.
(4) Drilling variable hole diameters.
Model BEZ 5 attatches directly to ‘OPG’ optical piping (section 61.1). Lateral adjustment modules LAU25,
or LAM25, may be used to aid centration of the zoom beamexpander to the input beam (sections 72.1, 72.2).
The input beam alignment is critical. A fine-tilt adjustment unit, TAU25, is available as an accessory. (See