CO2 Beam Expander

There are 2 types of beam expander: fixed and adjustable beam expanders. For the fixed beam expanders, the spacing between the two lenses inside the beam expander is fixed, but the spacing between the two lenses inside the adjustable beam expanders is adjustable. The lens material is ZeSe, which allows the red light to go through the beam expander.

We offer 3 types of beam expanders: fixed beam expanders, zoom beam expanders and motorised beam expanders at various wavelengths of 266nm, 343-355nm, 405nm, 633nm, 515-545nm, 808-980nm, 1030-1090nm, 155nm, 1850-1980nm, 10.6um. Other wavelengths and custom-designed beam expanders are available upon request. For more information, please feel free to contact us.

The specifications of the lenses used in the beam expanders are:

• Material: BK7 fine annealed, fused silica and ZnSe depending on laser wavelength.
• Diameter: -0.1mm
• Thickness: ±0.1mm
• Flatness: /4
• Surface Quality: 60-40 scratch-dig
• Coating: HR dielectric coatings R > 99%

Part number description: BEST-xxx-yy-T-AA
BEST --- BEST series beam expanders, zoom beam expanders.
xxxx------- laser wavelength: 10.6 means 10.6um, 532 means 532nm, 633 means 633nm.
yy --------- expansion ratio (magnification) in times
T ---------- type: T means adjustable/various/zoom beam expander; none means fixed beam expander.
AA -------- special purpose.
Example: BEST-10.6-3: 10.6um fixed beam expander, 3x.
BEST-10.6-3.5T: 10.6um zoom beam expander, max. 3.5x.

We may use the following abbreviations in the tables: WL=wavelength, MAG=magnification, CA=clear aperture, CA1=input clear aperture, CA2=output clear aperture, D1=input diameter, D2=output diameter, L1=total length of beam expander, M1=connection or mounting thread, D=diameter.

(1) Fixed Beam Expanders

BEST-W Series CO2 Laser Beam Expanders

BEC Series 10.6um Fixed Beam Expanders

BEH Series 10.6um Fixed Beam Exapnders

BEST-A Series 10.6um Fixed Beam Expanders

(2) Adjustable Beam Expanders

BEST-C Series 10.6um Adjustable Beam Expanders

BEST-W Series Beam Expanders

These beam expanders are designed specially for large pergent laser beam. Changing the distance between two lenses inside the beam expander can decrease the beam pergence to obtain better collimation of the laser beam. If they are used for large-pergence laser beam, you may turn the inner body to increase the spacing of two lenses and then to obtain better collimation laser beam. The material is ZnSe and thus the red light can go through the beam expander.

(3) BXZ Series Zoom Beam Expanders

Specifications

• For collimation of CO2 laser power<1.5KW/cm2
• Variable magnifications 2X-8X
• Galilei Design
• Adjustable pergence

More zoom beam expanders are available upon request. Please send us an email for more information.

(3) High-power CO2 Laser Beam Expanders

A: CBE Series Compact Beam Expanders

The high-power beam expander has a slide and lock focus setting. Normally this is set to infinity during manufacture. However, if a customer needs to adjust this to suit their system, the output should be coupled an adjustable pipe so this too can be adjusted to maintain an overall fixed length. Note that your input beam diameter should not exceed two-thirds of the input aperture. The output clear aperture is the same for all magnifications, 25mm. If your expanded beam diameter is 14.5mm to 22mm, the allowed input laser power can reach up to 500W. The input end has a M29 x 1.0 male thread and the output has the same female thread to take thread adaptors for coupling to other.

B: SBE Series Beam Expanders

The SBE series of beam expanders are designed for use with CO2 lasers of (relatively) small beam diameter, between the limits of around 2mm up to 12mm, and for power levels of up to 1kW CW. SBE units may be used to increase beam size, and reduce laser pergence accordingly. A wide range of magnifications is available to enable best performance to be obtained from the laser. The SBE series of beam expanders are of Galilean type, with two ZnSe lenses. The lenses are made from laser grade ZnSe and treated with ultra-low absorption anti-reflection coatings for 10.6μm. All models are externally identical. The focus range is from -10 metres, through infinity, to +1.6 metres. It is factory calibrated from infinity to +2 metres focus range. Please note that the indicated focus is geometrical, and the actual downstream beam waist position will depend upon the parameters of the laser beam. The focus mechanism is of the actuated-slide type, and actuation of the focusing ring drives the output lens position in a linear, non-rotary sense. This mechanism reduces beam wander usually experienced with rotary focus mechanisms.

The SBE series beam expanders can be used to reduce beam pergence and to help achieve very high energy densities from quite low laser power. For example, if used with a 10W Synrad laser, a model SBE/60 plus a TF25 focusing lens, would generate an energy density of around 20kW/mm² at the focus. Typical applications for the SBE series beam expanders with low power lasers include drilling holes in plastics, cutting paper and card, cutting man-made fibre material and rubber, and engraving decorative wooden plaques. In common with other beam expanders, the SBE series can provide a long-path of consistant beam quality. They may be used in conjunction with moderate power (several hundred watts) CO2 lasers to enable large cutting bed applications, such as the processing of sail-cloth.

C: BE25 Series Beam Expanders

>The BE25 series of beam expanders is designed for use with CO2 lasers of up to 2kW CW power. The units are water cooled and incorporate an actuated-slide focusing mechanism to reduce beam wander during focusing. By reducing beam pergence and allowing the user control over the ongoing beam characteristics, these industrial laser beam expanders can improve system Performance, especially in large moving-optics systems.

Technical specifications:

Type: Fully corrected Galilean type, with ZnSe lenses. Construction: Aluminium alloy, black anodised. Lenses mounted using indium wire to aid heat transfer. Cooling: Water (or air) cooled, via 8/6 size fittings. Focus range: From infinity down to 2.8 metres. Calibrated. Beam wander during focusing: 2 minutes of arc over full range. Output clear aperture: 35mm diameter. Fitting: Via standard 52.0 dia x 1.5 pitch coupling ring.

The actuated-slide mechanism drives the output lens in a linear motion, reducing beam wander that can occur in rotary mechanisms. The geometrical focus setting is calibrated from 2.8m to infinity. Please note that the downstream beam waist position will depend upon the laser beam characteristics as well as the focus setting. Geometrical focus is calibrated for a plane wave input. The specific applications for the BE25 series beam expanders are too numerous to list. In general, they are used by many system integrators in moving-optics cutting systems, long-bed anilox processing and a variety of systems where a controlled beam and increased focused energy density are desirable.

D: BE38 Series Beam Expanders

The BE38 series of beam expanders is designed for use with high power/large beam diameter CO2 lasers of up to 3kW power CW. These Galilean beam expanders use two ZnSe lens elements made from laser grade ZnSe and treated with ultra-low absorption anti-reflection coatings for maximum power handling capacity. BE38 series beam expanders use an actuated-slide focus mechanism to reduce beam wander during focusing. The units are water cooled. Use of these beam expanders can improve system performance by reduction of the beam far-field pergence and by providing control of the ongoing beam parameters.

Technical specifications:

Type : Fully corrected Galilean type, ZnSe lenses. Construction : Aluminium alloy, black anodised. The lenses are mounted using indium wire to aid heat transfer. Cooling : Water cooled via 8/6 size fittings. Focus range : From infinity down to 2.8 metres. Calibrated. Output clear aperture : 57mm diameter. Input clear aperture : 38mm diameter. Fitting : Via 70.0mm x 1.5 pitch connector ring. Beam wander during focusing : 2 arc minutes over full range.

The actuated-slide mechanism causes the output lens to be linearly repositioned when the focus control ring is rotated. This reduces the beam wander that can occur with rotary focus mechanisms. The geometrical focus position is calibrated from 2.8 metres to infinity. Please note that the downstream beam waist position will, in general, be different from the geometrical focus setting. The geometrical focus is calibrated for a plane wave input.

E. Modular Beam Expanders

The modular series of CO2 laser beam expanders provide a wide, versatile range of sizes and magnifications for laboratory and general industrial use with lasers of up to 1kW CW laser power. The range consists of a series of output sections, forming the main body of the beam expander, with output diameters from 25mm to 90mm. Input lens units plug into the main body to form the complete beam expander.

• Technical specifications (all models):
• Lenses: Laser grade ZnSe with ultra-low absorption anti-reflection coatings.
• Bodies: Aluminium HE30, black anodised.
• Output clear aperture: Defined by designation, eg "OP50" has 50mm clear aperture.
• Input clear aperture: Defined by designation, eg "IP14" has 14mm clear aperture.
• Magnification: Defined by designation, eg OP50 plus IP10 have, as a combination, a magnification of 50/10 = x5.
• Performance: Less than λ/20 residual spherical aberration.

Remark: Lengths "L" stated at infinity focus

Interchangeability

The two larger 'IP' units designated IP20 and IP25 may only be used with OP70 or OP90 bodies. Otherwise, all IP units fit all OP units. In order to fit IP20/IP25 in to the OP70 /OP90 bodies an adaptor sleeve is removed.

Input units

The size and shape of the 'plug-in' input units applies to IP designations from IP3.3 to IP14. The two larger input units IP20 and IP25 are shown in external view in the following figures. These may only be used with OP70 or OP90. Available models are given in the following table.

(4) Beam Expander Mount

The beam expander mounts are used to hold a beam expander, red pilot diode, mirrors with the screw M22x0.75mm. They are 4D adjustable for optics alignment at angles, positions.

• Model: SMH-13-048
• 4D adjustable (4-axil adjustable) (X and Y direction travel ±2mm, X and Z direction tilting ±4 deg)
• Suitable for the beam expander with a screw of M22x0.75mm
• Dimension: 60x60x45mm

Custom-made beam expander mounts available upon request.