Modular beam delivery units & equipment

Introduction

Model ESU25 shutter is a high-capacity unit designed for use with CO2 lasers of up to 2000W power.
A powerful rotary solenoid is used to rotate a mirror, which, in the ‘closed’ position reflects the laser
beam onto a water-cooled beam-dump. When the solenoid is actuated using the electronic power
supply provided, the mirror swings out of the beam which then passes unobstructed through the unit.
A return-spring is used to ensure that, should the power fail, the shutter will remain ‘closed’.
LED indicators are used to show ‘open,’, ‘closed’, and ‘error’ conditions. (See Safety Features).
The shutter can be triggered manually or via an externally provided 5V TTL signal.
Technical specifications, optical / mechanical
Construction : Aluminium alloy, black / dove grey Al. mirror, gold coated.
Clear aperture : 30.0 mm diameter.
Cooling : Water cooled, 8/6 fittings (dump) and 6/4 fittings (mirror).
Fittings, (2 off) : Retractable coupling rings, with 52.0mm dia x 1.5mm pitch threads.
Max CW power : 2000W CW.
Operation speed : Time to close < 200 msec, Time to open < 100 msec.
Beam dump : Built-in.
Solenoid : Rotary, 45-degree type.
LED display : Green = ‘open’
Amber = ‘closed’
Red = ‘error/fault’

Technical specifications, electronic

Power supply : Mains, 230/240V or 110/115V AC
Display/controls : (1) Mains on/off switch/indicator.
: (2) Shutter open/closed switch.
: (3) TTL (5V DC) input socket.
: (4) Manual/TTL control switch.

Safety Features

The optical clear aperture is mechanically limited to a size smaller that the mirror so as to avoid beam
overspill. Actual mirror size is 34 x 50mm.
As required by current legislation, the shutter has a manually operable lock mechanism. If the shutter
is locked ‘open’ (for initial setting-up) and no drive signal is present, the error LED will light. If the
shutter is locked ‘closed’ and a drive signal is present, the error LED will light. If the error LED is
lit, an audible buzzer will sound.
The beam dump unit is intended to be integral to the unit, and should not be removed except by a
skilled laser engineer.
NB:- Removal of the beam dump could cause a laser beam to be emitted from the dump aperture.
Operational notes
The recommended power limits (2000W CW) is set by reason of the limit on dumped power into the
internal beam dump. To maintain an even temperature at the beam dump of no more than approx 10
degrees above ambient, the cooling water needs to be circulated via the 8/6 pipe fittings at a rate of
>3 litres/min (at 2000W CW power) while the shutter is ‘closed’. Cooling water should be supplied
to the mirror via the 6.4 pipe fittings at a rate of approx 0.2 litres per minute.
The angular accuracy of the rotary solenoid is not sufficient for the ESU25 to be used as a 90 degree
beam-switch.

Associated equipment

Model ESU25 is a direct fit to OPG piping (section 61.1), and to various lateral adjustment
accessories (section 72).
For special-purpose applications, the beam dump may be removed and replaced with a standard
retainer/connector ring set. This allows other equipment (eg: a power meter) to be affixed to the
dump port exit. This work should be undertaken by ULO Optics or by a skilled laser engineer only.
See Safety Features above.