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BENTHAM | TLS120Xe Product Guide v1.3
Light. Measurement. Excellence.
2.2 Optical Design Overview
The TLS120Xe is a tuneable light source operating over the spectral range
280 nm to 1100 nm. It houses an ultra-quiet short-arc xenon light source,
starter and constant current power supply with a 120mm focal length
concave grating monochromator in a single 19” rack (4U) unit. With a single
mains power input, the TLS120Xe offers plug and play functionality, with
direct front panel control or automation over USB.
The arc of a short arc xenon lamp is placed at the primary focal point of an
AlMgF
2
coated ellipsoidal reflector. At the secondary focal point of the
ellipsoidal reflector is located the rectangular entrance slit of a concave
grating constant deviation monochromator. A four-position filter wheel is
located behind the entrance slit, fitted with a shutter and two long pass
filters (OS400 and OS700) to supress diffraction orders other than the first
diffraction order.
A 1200 g/mm, ruled concave diffraction grating (380 nm blaze wavelength) is
mounted on an on-axis rotating turret driven by stepper motor having a drive
resolution of 0.5 arcsec per step.
The grating spectrally disperses the broadband optical input light and re-
focusses the dispersed light onto a rectangular exit slit, transmitting a narrow
band of wavelengths defined by the largest width of the entrance and exit
slits. Rotating the diffraction grating allows selection of the transmitted
wavelength over the range 280nm to 1100nm.
A pair of biconvex lenses focus light transmitted through the slit onto the
optical fibre/ liquid light guide of choice. An iris diaphragm allows control of
the level of illumination.
The xenon lamp should be changed if it has failed or if the power output has
fallen below the recommended level of 87.5% of the initial output (nominally
2000 hours). The TLS120Xe includes a monitor photodiode and amplifier to
enable output monitoring during lamp alignment.
Please read section 1.6 for recommended replacement
lamps and section 3.2 for the lamp replacement
procedure.
The bandwidth of the TLS120Xe is defined by the width of the
entrance and exit slits as shown in table 1.
Please read section 3.1 for the procedure to change slits.
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