CO2mpact User Manual

Beam Delivery System for sub 500W lasers

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1Introduction ............................................................................................................3
Thread inserts ........................................................................................................4
Beam pipe C-BPxx .................................................................................................5
Extender pipe C-BPExx/yy .....................................................................................5
Retractable mount C-RM........................................................................................6
Pipe supports C-PS ................................................................................................6
Beam Expanders C-BEx.x......................................................................................7
Beam expander theory........................................................................................7
Manual attenuator, C-MA........................................................................................9
Principle of operation ..........................................................................................9
Attenuator use ..................................................................................................13
Reflection isolator C-RI.........................................................................................14
Principle of operation ........................................................................................14
Corner mirror block C-CM.....................................................................................15
In-line phase retarder C-CM-PR4 (& C-CM-PR2) ................................................16
Beamsplitter C-BS ................................................................................................17
Fine focus adjustment C-FA .................................................................................17
Centering cell C-CC .............................................................................................18
Lens nozzle assemblies C-LNxx ..........................................................................18
Shutter head unit C-SU ........................................................................................19
Description and use ..........................................................................................19
Internal circuit....................................................................................................19
Laser Shutter Controller LSC01 ...........................................................................20
Connections .....................................................................................................20
Operation ..........................................................................................................20
Circuit Operation ...............................................................................................21
Beam injector module, C-BI..................................................................................22
Power ................................................................................................................22
Diode Laser ......................................................................................................23
CO2 Laser Beam ..............................................................................................23
Alignment of Visible Beam ................................................................................23
Cross wire C-CW ..................................................................................................23
Thread adapters ...................................................................................................24
Optics ...................................................................................................................25
Focusing lenses 7.5ZLF38, 7.5ZLF63, 7.5ZLF100 and 7.5ZLF127 .................25
Silicon mirrors 9.8SIS3-00 and 10SIS3-00 .......................................................25
Phase retarders 9.8SPR3-90 and 10SPR3-90 .................................................25
Silicon mirror 11SIS3-00 ...................................................................................26
Beam combiner 9.8ZBS3-45-R .........................................................................26
Brewster windows ZBW5320MP and EZBW5320MP .......................................26
Beam Expander output lens 11ZLF63 ..............................................................26
Beam Expander input lenses ............................................................................26

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2Introduction
As the name suggests, CO2MPACT beam delivery is intended for small CO2 lasers, in this case, up to 500W
power and with beams up to about 12 mm diameter. From the laser output to the work piece, the beam
delivery consists of components that enable the beam to be handled with efficiency. The parts are easily
assembled with the aid of the thread inserts and the system can be firmly secured to a bench top with thepipe supports.
In the following sections, each of the individual parts is described. Some require very little explanation, butothers require considerably more detail in order to explain the optical function and its use.

‘Example’ of an assembled system. From top left to bottom right,
laser mount, attenuator, beam expander, pipe + pipe support,
shutter, beam injector, corner mirror block, extender pipe, fine
focusing unit, centring cell, lens and nozzle assembly. Some shortsections of beam pipe are between the various parts.

This section view shows how athread insert connects a lengthof pipe to a corner mirror block.

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Laser mounts C-LM and C-LMA
http://ulooptics.com/co2-laser-mounts

Available in two versions, these mounts allow the CO2MPACT equipment to be attached directly to the output
end plate of the laser. The screw hole pattern is arranged to match your laser. The central hole is threaded tomatch the thread inserts (see below) from which beam pipe and other items can be attached.
A small amount of clearance in the screw holes will allow some sideways movement to centre the beam tothe bore. If your beam is accurately perpendicular to the laser end plate then the C-LM will suffice, however,should you need to tilt the beam delivery over slightly to follow the beam then the adjustable version C-LMA
is recommended. This consists of two plates, the first being bolted to the laser and the second is adjusted for
tip and tilt using the three screws. A compressed O-ring sits between the plates to provide the ‘spring’ for the
adjustment.

Thread inserts

These stainless steel thread inserts are used to couple together the various parts of the CO2MPACT range.
They have a M29 x 1 mm thread and an inner diameter of 19 mm. Slots at each end allow some leverage totighten against a stop and undo them again.

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4Beam pipe C-BPxx
http://ulooptics.com/beam-tubes-supports-accessories

Beam pipes serve as a shroud to the laser beam so that accidental blocking of the beam cannot occur. In
particular, for Health and Safety reasons, skin exposure by a laser beam such as the CO2 beam should be
avoided. Beam pipes also serve to connect the other parts of the beam delivery system together, making it amore rigid structure. They can also be used to contain a purge atmosphere that has a slight positive
pressure. This helps to keep dust out of the beam path as well as stabilising the beam from the effects ofabsorbing gases.
The standard lengths are 30 mm, 50 mm, 100 mm and 300 mm. Using the thread inserts, longer lengths canbe created. An odd length can be made using the extender pipe. A 30 mm length can also be supplied with apurge nozzle (C-BPP30).
The internal bore is 19 mm and connection is made to other components by the thread inserts.

Extender pipe C-BPExx/yy

Extender pipe is a telescopic section of beam pipe that is used to bridge a gap that does not correspond to
the standard lengths of fixed length beam pipe. The extending section is a slide-and-lock mechanism. The
length range covered is 50 to 70 mm in one version (C-BPE50/70) and 85 to 125 mm in the second (CBPE85/125). As with normal beam pipe, thread inserts are used to connect to other parts and the bore is thesame 19 mm.
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5Retractable mount C-RM

The retractable mounts are used in pairs and fixed either side of a part that you may need to remove fromthe system without upsetting the position of other components. Alternatively, they can be used to lock othercomponents in a certain azimuth orientation. Attach them to the component using thread inserts and thenuse their coupling rings to connect to the beam pipe. The coupling rings, once unscrewed from the threadinsert, are simply pulled back to allow the part to be lifted out. The beam injector and shutter units aresupplied with these mounts.

Pipe supports C-PS
http://ulooptics.com/beam-tubes-supports-accessories

The pipe supports firmly clamp the beam pipe sections to a work surface at a height to match your laser.
They consist of 4 parts: the base, a middle section, and a V section to hold the pipe and the clamp. The basehas 2 slotted holes to allow mounting to optical tables that have a hole spacing of 25 mm or 1”. The hole
separation is 75 mm or 3”.
The middle section is the piece that is chosen to bring the beam pipe up to the correct height. Common laser
types catered for are those made by Rofin, Coherent, Synrad and Spectron. There is a small amount ofheight adjustment available by loosening 2 screws on the support’s side. Standard heights are 73, 78, 81 and123 mm.

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Beam Expanders C-BEx.x
http://ulooptics.com/beam-expanders

Beam expander theory
As the name suggests, a beam expander enlarges the diameter of a laser beam. This is done for two
possible reasons:
1)
2)

When focused, a larger diameter beam will give a smaller spot. Thus a beam is expanded to produce
higher energy densities on the target.
A large beam also has a smaller divergence and does not change its diameter as much when
propagating over many meters (unless deliberately defocused). In a flying-optics type system, this helps
to keep the energy density at the focus constant as the optics vary their distance from the laser and also
reduces the focus shift due to the wavefront curvature variation.

The above two points can be expressed mathematically by the equations:(1)
Where S = Focused spot diameter, F = Lens focal length, D = Beam diameter at the lens, M2 = Beam Msquared factor (not the magnification). Note that the focusing lens must be diffraction limited.
(2)
Where D0 = Beam waist diameter, θ = Beam far-field divergence (full angle). The right-hand side of thisequation is a constant for any particular beam, so as D0 increases, θ will decrease.
If a beam expander’s magnification is ‘m’, then the input and output beams are related by the following
equations:
(3)
(4)

(5)
Where D are the beam diameters and R the wavefront radii (see Fig 1). ‘G’ is the geometric focus setting of
the beam expander. On more expensive models than the CO2MPACT, this will be the value engraved on thefocus ring. Normally, however, G is set by experimentation. Note that if G is set to infinity (beam expander
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ULO OPTICS

FOCUS LOCK

has zero optical power), the output wavefront radius is not equal to the input wavefront radius, unless abeam waist is located at the input (RIn = ∞).

Fig 1: Definition of terms
The last equation (5) above relating the far-field divergence on the input and output sides, can generally besummarised by saying that all angles are reduced by m, including beam alignment errors to the optical axis.
CO2MPACT beam expanders
CO2MPACT beam expanders are optically identical to ULO Optics’s obsolete BSL12 series. The difference isthat the CO2MPACT version has a slightly longer body and is modified to take a thread insert at the output
end. The input end has a built-in thread. The slide-and-lock focus mechanism allows beam wavefront radius
to be adjusted. The central position being factory set for infinity focus. However, the actual setting needed,
will be determined by experimentation.
The magnifications available are listed the Table 1 below along with input clear apertures. Note that thelowest and highest magnifications possible in the housing are 1.3 and 7.0 respectively. Although a longer
housing is possible to cover magnifications 7 to 12.
Mag
Max input
beam dia(mm)
Input CA
(mm)

1.3

1.6

2.0

2.5

3.0

3.5

4.0

5.0

6.0

7.0

10

10

10

8

6.0

5.0

4.5

3.5

3.0

2.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.0

10.0

Table 1: Input clear apertures
The output lens is common to all magnifications and together with the mechanical length of the slide-and-lockslot, determines the focusing range of +1 metre through infinity to –1 metre. Thus the beam expander can beused as a ‘long working distance’ focusing lens. When used as such, however, the focal length is equal to theworking distance (=G) divided by the magnification, m, i.e. F = G/m
E.g. when a x7 beam expander is adjusted to focus over 1400 mm, the (effective) focal length is
1400 / 7 = 200 mm, not 1400 mm. You can use F = 200 mm in the equation above for spot size, S, provided
D is the input beam diameter (alternatively, you could use 1400 mm for ‘F’ and the output beam diameter for‘D’: both are larger by the magnification factor).
Beam Reducers
Occasionally, someone may wish to use a beam expander in reverse, as a beam reducer. In principle there is
no reason why this cannot be done, however, there are a few cautions to bear in mind:
1)
2)
3)

The power density at the output will increase with the square of magnification, m (‘m’ being themagnification of the beam expander).
The far-field divergence angle of the output beam and any angular misalignment errors of the beam,increase by the magnification, m. Centring the beam to the beam expander will therefore be more criticaland it may grow more rapidly than you expect.
The focusing becomes much more critical. The range will be approximately +1000/m2 through infinity to-1000/m2 millimeters. Therefore some short focusing distances are possible. It is advisable when setting
up the beam reducer, not to have any other optics further down the beam until the focusing is set
correctly. This will prevent possible damage from having a focused beam accidentally directed onto
another optical component.

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8Manual attenuator, C-MA
http://ulooptics.com/manual-attenuators

Principle of operation
The principle of operation is based on the ‘Brewster angle’. When linearly polarised light is incident on an airoptical material interface (uncoated), usually some of the light is reflected and some transmitted. However,when linearly polarised in the orientation shown in Fig 1 (known as ‘P’ polarisation), there is no reflected light;
100% is transmitted into the material, provided the angle of incidence is equal to the Brewster angle. This is
not so when the polarisation is in the perpendicular direction as shown in Fig 2 (known as ‘S’ polarisation).

Fig 1: P polarisation

Fig 2: S polarisation

If there is a mixture of polarisations then the situation is more complex, but the transmitted light will containless of all polarisations except P. By using a series of interfaces eventually the transmitted light will be all P
and some of the laser beam power is lost. Obviously, a window as 2 air/material interfaces.
The value of the Brewster angle is calculated by:(1)
Where ‘n’ is the refractive index of the material. Table 1 lists the values for ZnSe against different
wavelengths.

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λ (µm)n

IBrewsterTP (%) *TS (%)

0.633

2.591

68.90°

99.90

47.28

3.0

2.438

67.70°

99.99

49.73

7.0

2.422

67.57°

100

50.01

10.6

2.403

67.40°

100

50.33

12.0

2.393

67.32°

100

50.51

Table 1: ZnSe Brewster angle data (* with IBrewster set at 10.6µm value)
The Brewster angle does not vary much with wavelength so the transmittance does not vary greatly once set
for a particular wavelength. An attenuator based on the Brewster angle will work well over a broad range of
wavelengths.
(NOTE: there are versions for 10.6µm where coatings have been applied to the surface. These will not
function at other wavelengths).
A flat window tilted to operate at the Brewster angle of incidence is usually referred to as a Brewster plate (orwindow). In an attenuator, two of these are mounted in a ‘V’ arrangement as shown in Fig 3. Because of the
67.4° angle of incidence when ZnSe is used, the plates need to be 2.6 times longer than their width in orderto present a square profile to the beam. The ‘V’ configuration corrects for the beam displacement.

Fig 3: Arrangement in a ‘V’ configuration of 2 x ZnSe Brewster plates
There are 4 air/ZnSe interfaces (2 plates) in the attenuator, each transmitting 100% TP and 50.33% TS.
Consequently, after all 4 interfaces the net transmittance is 100% TP and 6.4% TS. These values represent
the limits for the transmittance of an attenuator.
To vary the transmitted power the plates are rotated about the beam axis. If θ represents the angle between
the direction of polarisation in the incident beam and the P plane of the Brewster plates, then thetransmittance of the attenuator is given by:(2)
Fig 4 plots the results in a graph.

Fig 4: Plot of transmission against rotation angle for a pair of uncoated ZnSe Brewster plates.
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10Less known is that the output plane of polarisation is rotated with respect to the input (denoted here by φ see Fig 5). As the attenuator is rotated, the plane of polarisation is ‘dragged’ with it, but at a smaller angle. It
actually reaches a maximum angle before reversing and dropping back to zero. This is due toFig 5: Definition of angles θ and φ.
the residual transmission of the S polarisation, which eventually dominates. The formula for the rotation isshown here and Fig 6 is a graph.

Rotation angle of plane of polarization, f (deg)

(3)

40

30

20

10

0
0

23

45

68

90

Rotation angle of attenuator, q (deg)Fig 6: Rotation of polarisation for a pair of uncoated ZnSe Brewster plates.
This is no problem if the process is polarisation insensitive, but where the output beam must have a fixedplane of polarisation (e.g. when the beam will subsequently be reflected off a phase retarder), then somecorrective action is required to rotate the polarisation back.
One way to accomplish this is by having a set of static Brewster plates afterwards. However quite a few canbe needed: 6 to ensure that the plane of polarisation remains within 1° of its original direction. The number ofplates can be reduced by using the coated type, although these have power handling restrictions (~ 500W).
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Alternatively, a second attenuator rotated by an angle in the opposite direction can re-align the polarisation
exactly. In both cases, the transmittance curve in fig 4 will be changed.
In summary, Brewster attenuators are most useful when the laser itself has no means of power control andthe process is polarisation insensitive. The polarisation must also be linear.
Coated Brewster Plates
By coating one surface of each plate with a special coating, it is possible to enhance the reflectance of the S
polarisation to 98% (from 50%) at the expense of a slight loss to the P polarisation (99% transmission
instead of ~100%). The result is that the minimum transmittance through the attenuator is now much lower at~ 0.04%. (2% of 2%). This works only at one wavelength though, 10.6µm. If you need an attenuator that has
a broader wavelength range, then you have to use the uncoated plate version.
The coating is a complex stack of layers, so the absorption limits the laser power to around 500W. However,this is the recommended limit for the CO2MPACT series anyway.
The corresponding curves for Fig 4 and 6 above are shown below in 7 and 8. Note that the transmission
curve closely follows Malus’s law (T = cos2θ) for a perfect linear polariser. Note also that for a perfectpolariser, the plane of polarisation in the output would follow the attenuator all the way round to 90°. For thecoated attenuator, however, the polarisation will still flip back to zero, but from a higher angle.

Transmission, T (%)

100

75

50

25

0
0

23

45

68

90

Rotation angle of attenuator, q (deg)Rotation angle of plane of polarization, f (deg)Fig 7: Plot of transmission against rotation angle for a pair of coated ZnSe Brewster plates.

80

60

40

20

0
0

23

45

68

90

Rotation angle of attenuator, q (deg)Fig 8: Rotation of polarisation for a pair of coated ZnSe Brewster plates.
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Attenuator use
The attenuator has a graduated ring with lock screw. Turning this ring rotates the Brewster plates inside andthe scale reads the nominal transmission (some later versions may have some extra numbers relating to thetransmission with coated plates).
With the ring set to ‘100’ (%), note that the P plane of the Brewster plates align with the large arrow at the
opposite end of the barrel. This arrow also shows the preferred direction of laser beam travel (more relevant
for the coated plate version).
With the ring locked in the 100 position, mount the attenuator in the system and rotate the whole body until
the large arrow lies in the known plane of polarisation. The P plane of the Brewster plates will then coincidewith plane of polarisation and the transmission will be at a maximum (~100%). For a more accurate set up,
monitor the laser power through the attenuator and adjust for the maximum power reading. In most lasers theplane of polarisation is either vertical or at 45° to the vertical, meaning that the arrow will either be uppermostor 45° to one side.
Finally, lock the attenuator to its supports both ends. Turning the graduated ring will now vary the transmitted
power, dumping the rest inside the body. For prolonged periods of dumping power and for higher powers,
the body will get hot. Fitting the water-cooled jacket will then be advisable.

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Reflection isolator C-RI
http://ulooptics.com/backreflection-isolators

Principle of operation
Optically the reflection isolator is identical to the manual attenuator, but is not intended to allow the out-going
beam power to be varied. It is installed in the system to allow the out-going beam to pass without loss.
However, any beam travelling back towards the laser and polarised in the orthogonal direction will beattenuated. Using two uncoated Brewster plates the transmittance will be 6.4% and two coated plates, about
0.04%.
In some laser systems this function is useful to prevent a beam reflection from the work piece travelling all
the way back into the laser cavity where it can cause instability to the power or damage in a high power laser.
The laser user will need to consult the laser manufacturer to estimate what power level can be tolerated by
the cavity and hence whether coated or uncoated plates are necessary (or even more than one isolator inseries).

Fig 1: Set up required for the reflection isolator
As mentioned above, the backward reflection must be polarised orthogonal to the out-going beam, sosomewhere in the system between the isolator and workpiece, the polarisation must be rotated through 90°
in order for the isolator to work. This will happen in a system where a λ/4 (1/4-wave or 90°) phase retardermirror is used to convert the linearly polarised beam into a circularly polarised one. Such an arrangement iscommon and is widely used for metal processing. The metals Aluminium and Copper are particularly noted
for sending back an unwanted reflection towards the laser. Fig 1 shows the arrangement that is required.
The out-going beam is polarised for maximum transmission through the isolator and 45° to the S and P
directions for the phase retarder mirror. After reflection the beam is circularly polarised and is used in thisstate to process the material. If a backward reflection occurs, it is reflected off the phase retarder a second
time and undergoes another λ/4 phase retardation. This second reflection does not ‘undo’ the first to give a
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zero retardation but adds to it to give a λ/2 (or 180°) retardation. The result is to re-create linear polarisation
but orthogonal to the out-going beam. Therefore the isolator will dump the beam.
Note that inaccuracies in the phase retarder coating and alignment of the polarisation to the mirror will resultin elliptical polarisation in the reflected beam, with a less efficient dumping of the power in the isolator.
Reflection isolator use
The isolator is installed in the same way as the attenuator, except there is no ring to adjust the power. The
arrow on the barrel defines the P plane of the Brewster plates and the preferred direction of propagation(more relevant for the coated plate version). Rotate the isolator in the beam until this arrow is aligned to thedirection of polarisation or using a power meter, gives the maximum transmittance. Then lock in place.

Corner mirror block C-CM
http://ulooptics.com/mirror-blocks

The C-CM corner mirror block uses 25.4 mm (1”) or 25 mm diameter silicon mirrors coated with theSupermax coating. Alternatively, a λ/4 phase retarder may be used. The mirror is mounted in a ring that has
tip and tilt adjustments, which are accessible through two holes in the cover plate. The latter holds a conicalspring that bears on the mirror back to provide some restraining force.
Mirror blocks will be supplied pre-aligned to within a few arc minutes, so should not need much adjustment. If
large amounts of adjustment are actually required (about +/-2° are available), then check the alignment of theincident beam and whether previous components are correct.
The mirror can be changed without affecting the alignment. To do this undo the two screws that hold thecover plate in place and remove, together with the spring. Pull on the edge of the mirror to remove (or use apiece of tape stuck to the mirror back). Replace with the new mirror and screw the cover plate on with thespring in place. Note that the large coil of the spring fits into the recess inside the cover plate.
The mirror blocks accept the thread insert or retractable mounts. One of the latter on the input side isrecommended as this allows the mirror block to be orientated in azimuth to any angle (useful when thecorner mirror block contains a phase retarder).
Note that the clear aperture on the C-CM is 16.4 mm.

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15In-line phase retarder C-CM-PR4 (& C-CM-PR2)

By combining four mirror blocks into a pair or periscopes it is possible to produce an in-line unit where thebeam in and beam out are collinear. Put a ¼-wave phase retarder into the first mirror block and normal zerophase mirrors in the other three and you have an in-line circular polariser unit. The C-CM-PR4 has to beorientated correctly with respect to the linearly polarised beam entering the device; 45° to the S and P planes– see Fig 1 below. Usually the plane of polarisation will be vertical or horizontal so that the unit itself will betilted over at 45°.

Fig. 1) Orientation of plane of polarisation with respect to S & P planes
It is also possible to order a C-CM-PR2 unit which is half the –PR4, consisting of two mirror block in aperiscope arrangement. If the user is not worried by the offset between the input and output beams, then the
C-CM-PR2 is a less expensive alternative.

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Beamsplitter C-BSThe C-BS is a fixed alignment beamsplitter unit that holds a 25.4 mm (1”) diameter x 3.0 mm thick opticalcomponent at 45° angle of incidence. The coating reflectance and polarisation type can be chosen to suit.
The clear aperture of the beamsplitter is 16.4 mm and the transmitted beam aperture is off-set by 1.5 mm to
the input to allow for the lateral displacement of the beam as it passes through a 3 mm thick ZnSe optic.

Fine focus adjustment C-FA
http://ulooptics.com/fine-focus-adjustments

This adjustable component is intended as a manual focusing device for a lens and nozzle assembly. Byturning the notched ring, the tube with the engraved scale lowers or rises at a rate of 1 mm per turn. 0.1 mmincrements are engraved on the outer sleeve. In total there is 20 mm of movement, engraved as 10-5-0-5-10
with 1 mm lines. A locking knob is provided to secure the focus setting.
The tube does not rotate as it slides: a pin at 90° to the locking knob rides in a slot to prevent rotation. This inturn prevents any beam wander from residual lens centring errors.
Both ends of the focusing unit have the thread to take the thread inserts.

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17Centering cell C-CC
http://ulooptics.com/centering-cell

The centering cell has the two thread insert connections on each side; one for the input and one for the
output. By adjusting the 3 screws in the body side, it is possible to laterally adjust one with respect to theother, either to precisely align the output to the beam or to introduce a deliberate offset. Note that the screws
need to be loosened on one side before those opposite can be screwed inwards. All three screws must be
tightened once the adjustment is made.

Lens nozzle assemblies C-LNxx
http://ulooptics.com/lens-nozzle-assemblies

The lens and nozzle assemblies come for 3 standard lens focal lengths: 38, 63 and 100 mm. The lenses aremounted in a separate cell that is screwed into the nozzle section. The C-LN100 is a C-LN63 plus an
extension piece and is shown above. The clear aperture inside the lens assembly is 17.5 mm.
The copper nozzle is removed by unscrewing the cap while to adjust its distance from the lens (to give thecorrect stand-off, +/-3 mm), unscrew the lock ring and screw the threaded tube in or out. Then tighten thelock ring.
The gas nozzle inlet allows a gas purge to be directed through the nozzle. With the standard lens, a pressureof up to 5 bar is possible. The inlet requires 6/4 tubing.
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Shutter head unit C-SU
http://ulooptics.com/external-shutter-units

Description and use
The shutter head uses a rotary solenoid to flip a Supermax coated Silicon mirror in and out of the beam.
When the shutter is closed, the beam is reflected onto a water-cooled beam dump. When open, the beam
passes straight through the unit. The open position is the electrically activated state of the solenoid.
Therefore, if the power were to fail, the shutter will close (a spring provides the force). LEDs on the shutter
head indicate the status: red for open and green for closed. The open and close positions are detected by
opto-reflective switches.
Power is provided via the 9-pin D plug connector and open/close status can also be monitored via thisconnector. An optional Laser Shutter Controller, LSC01, supplies power and monitors the status of the
shutter.
Note that the shutter is intended as a safety shutter and not for brief timing exposures. Using the LSC01,
typical opening and closing times have been measured at 30 and 60 msec respectively (as defined by theperiod in which neither limit switch ‘sees’ the mirror). Note that these times cannot be equalised due to thesolenoid limitations. The clear aperture is 19 mm.
The beam dump is water cooled via the connectors (6/4 M6). For a water temperature rise of ΔT °C and alaser power P Watts, the water flow rate should be 0.014P/ΔT litres/min. e.g. for a 10° rise in watertemperature and 500W, the flow is 0.7 litres/min.
The shutter heads are provided with retractable screw rings for mounting to beam pipe. Before installing the
shutter, check that the beam is centred to the beam pipe. Also note that there is an input and output side.
Sending the beam in from the wrong side will cause it to hit the rear of the mirror mount.
The shutter will operate in any orientation.
Internal circuit
For those who wish to provide their own controller, the drawing below shows the internal circuit of the shutter
head. Note that only 5 pins on the connector are actually used.
Any controller must supply +12V to pin 1 and be able to provide up to 1A. To open the shutter, pin 3 is taken
to 0V. This can be done via a simple switch or using a transistor.
The reflective opto-switches OPB704 detect the presence of the mirror. When the internal transistor sees
light from the diode reflected off the mirror, it conducts, pulling the base of the 2N3904 up and causing it to
conduct. The latter acts as a current booster to supply the indicator LED and pass the signal for external use
via pins 7 and 8 (going high to denote detection).
The reverse biased diode 1N4007 suppresses any back emf when the solenoid is deactivated.

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Laser Shutter Controller LSC01

Fig. 1: Front and rear panels
Connections
The LSC01 is supplied with two cables: a mains cable and one to connect to the shutter head terminated in
the D type plugs. The controller is powered from an 85V – 260V ac supply connected to the rear panel IEC
receptacle. The shutter is connected, using the cable supplied, to the rear panel 9-pin “D” socket labelled
SHUTTER. If required, the shutter can be controlled and monitored remotely via the other 9-pin “D” pluglabelled PC.
Operation
The front panel push button switches the controller mains power on or off. It is illuminated when powered on.
Before switching on, check that the toggle switch is in the closed position or if being controlled from a PC,
that a ‘close’ signal is being sent. This will ensure that the shutter does not open unexpectedly on power-up.
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The toggle switch opens or closes the shutter. The left position will open the shutter and the right position willclose the shutter. Note that if the controller is switched off at the mains, the shutter will default to the closed
position.
The red OPEN indicator will light when the shutter is open. The green CLOSED indicator will light when the
shutter is closed. (Note: Other ULO Optics shutters ‘ESU’ types have a manually operated lock that allows
the shutter to be locked in the closed position only. The yellow LOCKED indicator will light to indicate this.
The CO2MPACT shutter C-SU does not have a lock, so the yellow LED is inactive).
The status of the shutter can also be monitored via the rear panel 9-pin PC connector. Opto-isolators areused to give a grounded signal to indicate open, closed or locked and a high impedance for the inverse. The
shutter can be opened by applying 5V to the shutter enable pin 3 relative to GND. Note that to operate the
shutter from a computer, set the toggle switch to the CLOSED position.
Fig 1: D connector pins on rear of LSC01

PC

SHUTTER

pin

pin

1

no connection

1

+12V

2

no connection

2

no connection

3

3

Shutter enable

4

Shutter enable(+5V open, 0V close)
no connection

4

no connection

5

no connection

5

no connection

6

Locked(GND = locked, high Z = unlocked
Closed(GND = closed, high Z = not closed
Open(GND = open, high Z = not open
GND

6

Locked(+12V = locked)
Closed(+12V = closed)
Open(+12V = open)
GND

7
8
9

7
8
9

Circuit Operation
The shutter solenoid is connected between connector SHUTTER pin 1 (+12V) and pin 3 (TR1 drain). Whenswitch SW is switched to CLOSE, the gate of TR1 is pulled low by R2 and so TR1 is switched off. Therefore
no power is applied to the solenoid and the shutter assumes the default-closed position.
When SW is switched to OPEN, TR1 gate is pulled up to +12V and TR1 is turned on. This provides a current
path from +12V through the solenoid to 0v, and so the solenoid energises and the shutter opens.
The shutter status switches are connected between +12V and connector SHUTTER pins 6, 7 and 8. When
the OPEN status switch closes, it connects R1 to +12V so that LED1 lights and current flows through theemitter of the opto-isolator, IC1 causing the output transistor to turn on. Operation of the CLOSED state issimilar. Note that the ‘Locked’ function and LED3 are not relevant to the C-SU.
If SW is in the CLOSE position, then the shutter can be controlled via connector PC. If PC pin 3 has +5V
applied with respect to pin 9, then current passes through fourth opto-isolator IC1 emitter and IC1 transistor
is turned on. This will pull up the gate of TR1 and so turn it on. The solenoid will be energised and the shutter
will open.

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Fig 2: Internal circuit of LSC01 controller
Note that if you wish to control the shutter using a higher voltage than 5V, then you need to add anexternal resistor in series with R4 (390R). The value should be, R = 80Vcontrol – 390 Ω and its power
rating > R/6400 W.
Also note there are no pull-up resistors to the status pins. They have been left as open collector, so thatthe user can select the correct value according to their supply and desired signal.

Beam injector module, C-BI
http://ulooptics.com/pilot-laser-coupling-unit

This module allows a visible red laser beam to be aligned with the invisible infrared beam. This serves toact as an alignment aid further down the beam and as a reminder that the infrared beam is also present.
Power+5-6 V (30 mA) is required at the jack connector to switch the laser on and light the LED indicator on theside. The power supply supplied for this purpose is voltage switchable and polarity reversible. PLEASEREAD THE INSTRUCTIONS PROVIDED. IN PARTICULAR, THE WRONG POLARITY WILLULO Optics Ltd
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DAMAGE THE LASER. IF IN DOUBT, CHECK THAT THE TIP OF THE 2.5 MM JACK HAS THE +6V
ON IT.
Diode Laser
Inside the C-BI is a visible (red, 650 nm) laser of 0.8 mW power. As is usual for this type of device DO
NOT STARE INTO THE BEAM DIRECTLY AND ENSURE THAT YOUR EYES AVOID ANY
REFLECTED BEAMS.
CO2 Laser Beam
This is to be directed into the input aperture. Make sure the beam is aligned to the centre of the beam
pipe before installing the C-BI.
The CO2 beam will pass through the ZnSe beam combining optic and emerge at the output aperture
together with the visible laser beam. Note that the clear aperture of this unit is 14.5 mm.
IF YOU SEND THE CO2 LASER BEAM INTO THE WRONG APERTURE, A SMALL % OF THE
POWER IS REFLECTED UP TO THE DIODE LASER AND IT’S COLLIMATING LENS. DEPENDING
ON THE POWERS INVOLVED, THIS COULD DAMAGE THE DIODE LASER.
Alignment of Visible Beam
Before coupling to the beam pipe stick a piece of masking tape over the output aperture to check thatthe beam is more or less central.
Turn the CO2 beam off. Mount the C-BI in the system and install a target or cross-wire further down thesystem.
Use an Allen key to adjust the tip and tilt screws A and B until the visible beam is central. Do not press
down on these screws otherwise you will compress the springs that you are trying to adjust.
Look for a clean beam. Any spurious flares or arcs will indicate that the tilt is so far out that the beam isreflecting off the inside of the beam pipe.
Next either remove the C-BI or retract the beam pipe at the output side. Again place a piece of masking
tape over the aperture. Adjust the two screws X and Y to centralise the beam. There is a few mm of
movement available and the total area covered is circular.
When X and Y come loose while unscrewing or go tight while screwing in, the laser mount inside hasreached the limit.
The alignment process is iterative; adjust A and B to centralise the beam in the ‘far field’ and adjust X
and Y for the ‘near field’.
Finally, you may wish to make some fine adjustments with the CO2 beam on.

Cross wire C-CW

This useful item allows you to align the laser beam. It is a thread insert with a pair of copper wires andcan therefore be screwed in at any location between parts to check for a central beam. Once the beamis aligned, replace it with a normal thread insert.

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A quick beam burn on card or viewing the beam on a mode plate will show the silhouette of the wires.
Make adjustments until the silhouette cross is central to the beam. You need to check the alignment avarious places, working your way from the laser to the work piece.
Any odd mode pattern may indicate that the beam is reflecting off the inside of a pipe or is being clippedsomewhere.

Fig 1: Aligned (left) and mis-aligned (right) beam burns

Thread adapters

Should the need arise where you wish to couple other beam delivery equipment to the CO2mpact range,these 4 adapters should help. They have the M29 x 1 mm thread and a ¾-32UN thread in the male andfemale combinations.

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Optics
Focusing lenses 7.5ZLF38, 7.5ZLF63, 7.5ZLF100 and 7.5ZLF127
These 3 lenses are used in the C-LN nozzle assemblies. They are all 19 mm diameter and have anedge thickness of 2.0 mm. When mounted in a nozzle assembly the clear aperture will be 17.5 mm. The
effective focal length (EFL), back focal length (BFL) and flange focal length (FFL) are as follows (see Fig
1):
Lens

EFL

BFL

FFL

7.5ZLF38

37.9 mm36.0 mm35.5 mm

7.5ZLF63

65.3 mm

61.8 mm61.4 mm

7.5ZLF100

100.0 mm

98.4 mm98.3 mm

7.5ZLF127

127.0 mm

125.5 mm

125.3 mmFig 1: Definition of EFL, BFL and FFL
All the lenses are made from laser grade CVD ZnSe, to the optimum meniscus form for focusing
purposes and each surface is anti-reflection (AR) coated for 10.6µm.
Silicon mirrors 9.8SIS3-00 and 10SIS3-00
Made from monocrystalline mirror grade Silicon, these mirrors are fitted into the C-CM corner mirror
blocks. The mirror block will take either size, 25 or 25.4 mm diameter. They are coated with ULO’s
Supermax coating, giving 99.85% reflectance at 10.6µm and 45° incidence. The mirrors also are of ‘zero
phase’ type.
Phase retarders 9.8SPR3-90 and 10SPR3-90
These differ from the above Silicon mirrors in the coating. The SPR type is designed to convert thelinearly polarised laser beam into circular polarisation by means of a 90° phase shift difference(retardance) between the S and P components. This has processing benefits for some materials (e.g.
metals). They fit into the C-CM corner mirror blocks and C-CM-PR4 –PR2 units. The mirror block has tobe orientated with respect to the plane of polarisation as illustrated below. A retractable mount (C-RM)
may therefore be needed on the input side.

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Silicon mirror 11SIS3-00
This Supermax coated mirror is 28 mm diameter (1.1”) and is used only in the C-SU shutter unit. With
the shutter closed, it reflects the beam into a water-cooled beam dump.
Beam combiner 9.8ZBS3-45-R
This optic finds use in the C-BI beam injector unit. Angled at 45° incidence, the CO2 laser beam will betransmitted while the red visible laser strongly reflected off one surface.
Brewster windows ZBW5320MP and EZBW5320MP
Brewster windows for use in attenuators and reflection isolators are made as ‘matched pairs’. A
Brewster window works best if it has a slight wedge (1’ – 3’). However, this wedge deviates the beam
going through it. But by using an identical second window with the wedge orientated opposite to the first,
the angular beam deviation is corrected. The beam lateral displacement is also corrected because bothwindows have the same thickness.
The windows are 53 x 20 x 3 mm. Angled at 67.4° to the incident beam, they present a 20 mm squareprofile.
Beam Expander output lens 11ZLF63
For all C-BE magnifications, this is the common output lens. It is a standard lens and is used extensively
for other applications.
Beam Expander input lenses
There is a different input lens for each magnification. Each is shaped to correct the spherical aberrationof the output lens.

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26Request a Quotation
Requesting a quotation is easy. Simply identify the components you need and fax this form back to us+44 1438 767 500.
Contact Details
Name
CompanyCountry
Tel
Fax
Email
Your Laser
Laser Manufacturer
Laser Power (W)Laser Model
Optical Axis Height (mm)Beam Pipes
Pipe Description

Part Number

30 mm long

C-BP30100 mm long

C-BP100

300 mm long

C-BP300

Adjustable 85-125 mm long

C-BP85/125

Qty

Beam Supports
Beam Support Description

Part Number

73 mm highC-PS7378 mm highC-PS7881 mm high

C-PS81123 mm high
Other (please specify…)_____mm highC-PS123

Qty

C-PSXXX
Qty

Retractable Mount

C-RM

Qty
Corner Mirror

C-CM

Beam Expanders
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Beam Expander Description

Part Number

1.3 magnification

C-BE1.3

1.6 magnification

C-BE1.6

2.0 magnification

C-BE2.0

2.5 magnification

C-BE2.5

3.0 magnification

C-BE3.0

3.5 magnification

C-BE3.5

4.0 magnification

C-BE4.0

5.0 magnification

C-BE5.0

6.0 magnification

C-BE6.0

7.0 magnification
Other (please specify…)_____mm highC-BE7.0

Qty

C-BEX.X
Qty

Reflection Isolator

C-RI
Qty

Manual Attenuator

C-MA
Qty

Shutter Unit

C-SU
Qty

Beam Injector Module

C-BI
Qty

Fine Focus Unit

C-FFA

Lens Nozzle Assemblies
Lens Nozzle Description

Part Number

38 mm FL (lens with nozzle)

C-LN3863 mm FL (lens with nozzle)

C-LN63

100 mm FL (lens with nozzle)

C-LN100

Qty

For further information or to discuss your requirements with a member of our sales team, please contactus.
Tel: +44 1438 767 500
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28