Irradian L203 SMU User manual

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Handbook Ref No. MH070/Issue I
File Ref: L203SMU-vI.doc

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     1. Introduction
2. Specification
3. Operation
4. Eyepiece Adjustment
5. Lens Care
6. Mounting
7. Lens Selection Chart
8. Use of Extension Tubes
9. Environmental Care, Recycling and Disposal

L203 SMU Supplement Irradian Limited
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The Irradian L203 SMU203 Photometer is a customised portable
instrument designed for accurate measurement of spot luminance and
(optionally) luminance in cd.m
-2
or footLamberts and (optionally)
illuminance in lux or footcandles, according to the type of head supplied
with the unit.
The photometer comprises of a hand held display unit with micro
processor control, a detector / amplifier assembly / connecting cable,
spot measuring unit and an intermediate photopic filter ring, and other
possible accessories of a cosine corrected photopic filter ring for
illuminance measurements (L203 illuminance/luminance model) and a
photopic 6°field of view lens assembly.
The reflex viewing spot measuring unit, model SMU203 is a compact
telescope with off-axis eyepiece, permitting accurate measurements of
luminance when used in conjunction with the L203 photometer, detector
and photopic filter. The eyepiece provides a view of the imaged scene
superimposed on an aperture mirror. The aperture (seen as a dark circle
spot in the centre of the field of view) allows light to travel directly to the
detector or light guide. This method of detection gives high levels of
immunity from scattered light.

Irradian Limited L203 SMU Supplement
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DISPLAY UNIT (Ranges:)
Luminance with Up to 4 full scale decades measuring from:
SMU203-25/50/75 0 to 199.99 cd.m
-2
(25/50/75 mm f/l lens) 0 to 1999.9 cd.m
-2
0 to 19999 cd.m
-2
0 to 19999 x 10 cd.m
-2
Resolution 0,01 cd.m
-2
on range 1
(Optional) Up to 5 full scale decades measuring from:
0 to 19.999 fL
0 to 199.99 fL
0 to 1999.9 fL
0 to 19999 fL
0 to 19999 x 10 fL
Resolution 0,001 fL on range 1
For details of the ranges associated with the optional illuminance filter ring and luminance
6°field of view accessories, please refer to the L203 & L203 Lux handbook.
Calibration Absolute calibration accuracy estimated as
± 5.0 % traceable to NPL standards.

L203 SMU Supplement Irradian Limited
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Interchangeable Lenses
Eyepiece
Thread Mount to Irradian
Detectors or Optical Fibre
Light Guides
Detector and Filter
Combination
SMU203 Spot Measurement Accessory
1 / 4 UNC
Tripod Mount

Irradian Limited L203 SMU Supplement
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SMU203 Spot Measurement Accessory
Detector / Amplifier / Digitiser
Intermediate Filter Ring
Tilted Aperture
Mirror
(Alternative Spot
Dia’s available)
Mounted on
removeable Angled
Rod for ease of
replacement
Lens 25mm / 50mm /
75mm Focal Length.
Available with
Extension Tubes for
macro use.
Eyepiece permits view of
target. Mirror Aperture
seen as black spot.

L203 SMU Supplement Irradian Limited
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SPOT LUMINANCE SETTING UP
1) Carefully screw the CIE-INT intermediate filter ring to the SMU203
telescope and the DET203Vis detector to the intermediate filter ring.
Remove the rear lens cap and screw either the 25, 50 or 75 mm 'C'
mount lens to the SMU (including any other optical components such
as a x2 converter or extension tube). If an extension tube is fitted
check the calibration certificate for the multiplication factor.
2) With the unit OFF, plug the detector 8 way connector into the socket
on the top of the display unit.
3) Press and release the power switch on the L203 display key pad. The
micro controller will initiate with the display momentarily showing:-
The radiometer will now search for the optimum range on the detector
amplifier. A typical display is shown below.
An LED will illuminate indicating the units. This will be the same units
prior to the last power off.
4) Press and release the UNITS switch to select the correct units for
luminance measurements. The correct setting will be one of cd.m
-2
, fL
or Aux as detailed on the calibration certificate, supplied with the
meter.
5) View the source to be measured by sighting through the eyepiece
viewer, noting that the size of the source must be greater than the dark
circle spot observed on the reflex mirror. Light sources that appear to
be totally obscured by the black spot will not be accurately measured.
In this case move toward the source until it overfills the spot.

Irradian Limited L203 SMU Supplement
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Important note: In all situations other than darkroom operation, the
eyepiece blanking cap must be used to cover the viewer once the
telescope has been correctly aligned with the target source. Failure to do
so may lead to incorrect luminance values being given.
ZERO
It is recommended that the photometer amplifier is nulled periodically. To
do this place lens caps over both the front of the lens and the eyepiece. It
is important that both caps are in place before commencing the zero
operation as it is possible to obtain a false zero level (and consequently
incorrect readings) if ambient light levels are high and either of the optical
inputs are unblocked.
Press and release the ZERO switch, the display will show:-
The micro controller will now measure the amplifier offset on each of the
available gain ranges and store these values in the non-volatile memory.
All subsequent measurements will first have one of these offsets
subtracted before displaying the measurement.
At the end of the nulling sequence the display will show :-
Note: If the units fL are in use, the display will show 0.000 following the
nulling sequence.
Remove the light covers. The equipment is now ready for use.
AVERAGE
When the light is unstable, press and release the MODE switch. The
photometer will now switch to manual ranging, Manual LED on, if not yet
previously in manual ranging. The Average LED will now switch on, but
the Units LED will remain unchanged.