Irradian PR203 Instruction Manual
Handbook Ref No. IH001/Issue D
File Ref: PR203-v5D.doc
1. Introduction
2. Specification
3. Operation
4. Spectral Irradiance Measurements
5. Cosine Angular Response
6. Calibration Description
7. Care and Maintenance
8. Battery Replacement
9. Block Diagram
10. Programming via the RS232 Interface
11. Environmental Care, Recycling and Disposal
PR203 Radiometer Irradian Limited
1
The Irradian portable phototherapy radiometer model PR203 is designed
specifically to measure directly the irradiance of blue light for the
treatment of hyperbilirubinaemia in new born babies.
The photodiode and colour glass filters are designed to give a spectral
response closely matching the bilirubin phototherapy action spectrum.
Good blocking of the detectors response outside the bandpass ensures
the radiometer does not measure non-therapeutic light. The cosine
corrected diffuser input ensures accurate measurements where ever the
light source.
The radiometer comprises of a hand held display unit with micro
processor control and a detector / amplifier assembly with connecting
cable and associated filters. The sensor in the detector assembly is a
silicon photodiode with excellent linearity and long term stability.
Note: The PR203 is NOT an ultra violet radiometer and should NOT be
use to measure the output of ultra violet lamps in UV phototherapy
treatment.
Irradian Limited PR203 Radiometer
2
DISPLAY UNIT
Controller: 80C51 8bit micro-processor with a 3.1684MHz
clock.
Memory On board non volatile RAM for calibration
factors and set-up parameters.
Key Operation 8 switch key board with 11 LED indicators.
Power Switch Microprocessor reset at switch on.
Unit settings stored prior to shut down.
Serial Interface Three wire RS232 serial interface.
4800 baud, no parity, 1 stop bit.
Integration Time 0.33s
Conversion Scale 17 bit
Accuracy: Measurement accuracy ±1digit with a
linearity error of <1%.
Display: 4½ digit LCD display. Character height 10mm.
Display illumination: A LED back light can be switched on to
illuminate the display for readings in low
ambient light situations.
Power Supply: 9 volt PP3 type battery.
Power Consumption: Shut down mode <5µA
Operating 10 - 20mA
LED back light ~20mA
Battery Life ~ 50 hours without backlight use
PR203 Radiometer Irradian Limited
3
(continued):
Ranges:
i) Irradiance
Up to 4 full scale decades measuring from*:
0 to 19.999 µW/cm
2
/nm
0 to 199.99 µW/cm
2
/nm
0 to 1999.9 µW/cm
2
/nm
0 to 19999 µW/cm
2
/nm
Resolution 0.001 µW/cm
2
/nm on range 1.
* Other ranges available on request.
Calibration:
Absolute calibration accuracy,
±7.5% to national standards.
Irradian Limited PR203 Radiometer
4
(continued):
Front Panel Controls:
RANGE Select auto ranging or manual range control.
SOURCE Select between each of the three measurements
of irradiance from different light sources;
Halogen, Fluorescent or LED in µW/cm
2
/nm.
ZERO Initiates a zero or background measurement
routine on all five ranges.
HOLD/RUN Display is held at present reading until HOLD
button is pressed again.
Select to run or hold a special mode.
MODE Select between AVERAGE, MIN, MAX and
INTEGRATE modes.
FUNCTION/RESET Press to reset function values to zero.
RESET Press to return to normal measurement mode
from manual range mode or special modes.
Note the display hold is not reset.
Power on / off button.
Display backlight on off button.
Display backlight will switch off after a
programmable delay, factory setting 60 secs.
Connectors: 8 pin DIN type detector connector.
5 pin DIN type RS232 connector.
Temperature Range: 0 to 40°C. 80% RH.
Dimensions: 150 x 80 x 45mm.
High impact polystyrene.
Weight: 350g
PR203 Radiometer Irradian Limited
5
(continued):
DET203450 DETECTOR
Amplifier PCB Photodiode
Cable
Glass Filters
Cosine Diffuser
The DET203450 detector comprises of an aluminium housing,
photodiode, PR203 filter and PCB assembly.
Detector: 5.2 mm² High stability GaAsP photodiode.
Spectral Response: Refer Figure 1.
Angular Response: Accurately cosine corrected to Lambert's
Cosine Law. Maximum error is less than ±5%
from true response to 70° from normal
incidence, reference Section 5.
Temperature Coefficient: <0.3 %/°C
Amplifier Gain 10
6
V/A to 10
3
V/A
Current to Frequency 0 - 0.5Mhz
Linearity Error: <1% across range
Temperature Range: Operation: -10 to +60°C
Storage: -20 to +70°C
Detector Housing: Black anodised aluminium alloy housing.
Cable: 1 metre multicore cable to 8 pin DIN type
connector
Weight: approx. 140g
Irradian Limited PR203 Radiometer
6
(continued):
DET203450 Detector
Typical Spectral response
0
10
20
30
40
50
60
70
80
90
100
400 415 430 445 460 475 490 505 520 535 550
R
e
s
p
o
n
s
e
%
Wavelength (nm)
Figure 1
PR203 Radiometer Irradian Limited
7
SETTING UP
1) With the unit OFF, plug the detector 8 way connector into the detector
socket on the top of the display unit.
2) Clean the white diffuser on the detector if it is marked or dirty.
3) Press and release the power switch
on the PR203 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 and another to indicate
which light source is required. This will be the same source prior to
the last power off.
4) Press and release the SOURCE (bottom middle) switch to select the
correct source required. For quartz tungsten halogen sources, the
correct setting is Halogen. For irradiance measurements with a
fluorescent source, the correct setting is Fluorescnt. and with a blue
dominant wavelength LED the correct setting is LED.
5) It is recommended that the radiometer amplifier is nulled or zeroed
periodically. Place the supplied blanking cover over the detector.
Press and release the ZERO switch and the display will momentarily
show:-
Irradian Limited PR203 Radiometer
8
(continued):
6) The micro controller will now measure the amplifier offset on each of
the 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:-
7) Remove the light cover from the detector. The equipment is now ready
for use.
AVERAGE
When the light is unstable, press and release the MODE switch. The
radiometer 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 SOURCE LED will remain unchanged.
To start an average sequence press and release the HOLD/RUN switch.
Immediately the display will show a fluctuating signal, reflecting the light
source fluctuations. After a short time the amplitude of the fluctuations
will decrease and the display will begin to show a reading which
represents the average light level during the period of the measurement.
At any time the averaging process can be halted by pressing the
HOLD/RUN button. The display will flash ‘HOLd’ intermittently.
At any time the averaging sequence can be reset by pressing and
releasing the FUNCTION RESET switch.
If the light level fluctuations are large and any one reading causes the
detector amplifier to overload at this range the averaging process will be
terminated and the display will show:-
To avoid an overload conditions RESET the radiometer and Manually
change the RANGE to a lower lever. e.g. from a 34.00 range to 34.0.
PR203 Radiometer Irradian Limited
9
(continued):
MIN & MAX LEVELS
During an average measurement sequence the maximum and minimum
values attained in the period are recorded. Press HOLD to halt the
averaging sequence. Press the MODE button to select between Average,
Min and Max. Note the Integrate display may overload and show - 0 L -.
It is also possible to view a MIN or MAX recording sequence by selecting
MIN or MAX prior to selecting RUN.
Press FUNCTION RESET to set the maximum and average values to
zero and the minimum to - 0 L -. Note the FUNCTION RESET will
operate during a measurement sequence or in the HOLD mode.
INTEGRATE
For measurements of the integrated dosage or exposure press the
MODE switch to select Integrate. Press the RUN switch to start the
measurement. The display will now autorange as the dosage increases.
Note the detector amplifier will not autorange and as with Average
measurements if the amplifier overloads the display will show - 0 L - and
the measurement will halt.
Units for integrated measurements are µJ/cm²/nm.
At the end of the integration period HOLD the display. Use the MODE
switch to also display the Min,Max and Average values.
Press FUNCTION RESET to set the integrate, maximum and average
values to zero and the minimum to - 0 L -. Note the FUNCTION RESET
will operate during a measurement sequence or in the HOLD mode.
Irradian Limited PR203 Radiometer
10
IT IS IMPORTANT TO NOTE THAT THE PR203 IS A BLUE LIGHT
PHOTOTHERAPY RADIOMETER AND NOT SUITABLE FOR THE
MEASUREMENT OF ULTRA VIOLET LAMPS.
IRRADIAN OFFER A RANGE OF ULTRA VIOLET RADIOMETERS
INCLUDING THE UV201, UV202 AND UV203.
Spectral irradiance is the measurement of radiometric light per unit area,
microwatts per centimetre, per unit wavelength (µW/cm
2
/nm). The part of
the spectrum to be measured is defined by the filter fitted onto the
detector and matches the bilirubin action spectrum. Ideally this should be
a filter with a square spectral response. In practice it rarely is and the
filter is defined with a peak response wavelength and a full width half
maximum, FWHM bandwidth. In all applications it is vital to know the part
of the spectrum being measured by the detector and filter, and if possible
to know the spectrum of the light source. In addition the radiometer
should be calibrated to best suit the measurement conditions. It may
even be necessary to have more than one calibration factor for the same
detector and filter combination.
For most applications the measurement plane is horizontal and a cosine
corrected diffuser is fitted to the front of the detector assembly. If the
working surface is not horizontal then placing the detector on or parallel
to the worktop is a more representative measurement of irradiance.
Note that all the light sources in the hemisphere above the detector will
contribute to the measurement. The sources may be obvious, lamps or
windows or even walls or other reflecting surfaces. Take care not to
shadow the detector during all measurements.
For routine measurements of a phototherapy lamp it is necessary to
record the distance to the lamp, the position of the detector with respect
to the lamp and the orientation of the detector.
PR203 Radiometer Irradian Limited
11
Spectral irradiance is a measurement of the amount of light incident on a
unit area, per unit wavelength (µW/cm²/nm). Any detector will measure
this reliably when measuring a beam of light perpendicular to the
detectors surface, however when measuring scattered light or light from
an extended source the sensor must have an accurate response over its
180°field of view. More importantly, this response should be proportional
to the cosine of the angle of light incident on the detector. This comes
from the fact that the projected area of any surface at an angle of i is
proportional to cos(i).
To ensure that the integration of light from all angles is correct, the
cosine diffuser matches the angular response so that response of the
detector decreases with cos(i) as the angle between the source and
detector increases from 0 to 90°.
DET203450
True Cosine Response
Figure 4
Irradian's cosine diffusers are corrected to match the cosine response to
within ± 5 % up to angles of 70°. This ensures that the meter correctly
reads the visible light flux density whether it is measuring light from an
extended or a point source.
Irradian Limited PR203 Radiometer
12
Irradian holds a number of tungsten halogen and deuterium lamps and
silicon photodiode standards which are routinely calibrated by the
National Physics Laboratory in the UK.
Four methods for calibrating the radiometer are available:
i) Radiometric calibration with monochromatic light at 450nm in units of
W/m
2
.
ii) Radiometric calibration with monochromatic light at 450nm, the
sensitivity is then divided by the bandwidth at FWHM to give a
calibration in units of W/m
2
/nm.
iii) Spectroradiometric calibration. Each different phototherapy light
source is scanned with a spectroradiometer between 425 and 475
nm. The total integrated irradiance is then recorded and divided by the
spectral range to give calibration in units of µW/cm²/nm with the
PR203 radiometer calibration adjusted to match the
spectroradiometer.
iv) Each spectroradiometric value in (iii) can be adjusted with the action
spectrum to form a weighted spectral irradiance with the PR203 set to
match this.
Note the spectroradiometric calibrations are dependent on the light
source. It may be necessary to use correction values if accurate
measurements are required for many different phototherapy type lamps.
As with all measuring equipment a routine calibration is recommended,
typically annually, but with frequent use by a number of different users a
shorter recalibration period may be necessary.
PR203 Radiometer Irradian Limited
13
1) The PR203 display unit can be cleaned using a moist cloth with
detergent. Do not use solvent or alcohol to clean surfaces.
2) The diffuser on the detector should be kept clean at all times.
3) The radiometer is a precision instrument, protect from shocks.
4) Avoid supporting the detector by the multi core cable.
1) Switch off the radiometer before changing the battery.
2) Slide open the battery compartment on the back of the radiometer and
pull out the battery. Disconnect from the battery clip
3) Replace with a size PP3 9 volt battery.
4) Place battery inside compartment and slide cover closed.
5) Note it will be necessary to switch on and off the radiometer before
normal operation will commence.
Irradian Limited PR203 Radiometer
14
Diffuser
Filter
Detector
Amp
Gain Control
v to f Counter
µController
Keypad
Liquid Crystal
Display
Display Driver
RS232 Driver
& LEDs
Detector Amplifier
Micro-Controlled Display Unit
PR203 Radiometer Irradian Limited
15
!
! !
!
Serial Port Settings: 4800 baud, no handshaking
Single letter commands
S Toggle through possible gain ranges (manual mode)
Reset to autorange with R command.
U Toggle through possible light sources, Halogen, Fluorescnt.
& LED as applicable
F Toggle through possible functions
I Function reset
H Toggles hold/go
Z Zeros light meter
R Resets light meter
B Toggles backlight
s Sends data continuously via the RS232
o Sends one set of data via the RS232
Irradian Limited PR203 Radiometer
16
!
! !
!
(continued):
10.1 Windows 3.1 & Windows 95
Setting up remote control via Microsoft TERMINAL.EXE
1) Connect the cable between the RS232 socket on the light meter and
the COM port on the PC.
2) Switch on the light meter.
3) Run Terminal program.
4) Go to the Settings / Communications screen and set the baud to 4800
and the COM port to suit.
5) Go to the Settings / Text Transfers and select Line at a time with
1/10th second delay.
6) Check the RS232 link by a switch to the manual range, LED on using
the command 'S', (capital S).
7) Reset to the auto range, LED off using the command 'R', (capital R).
8) Type 'o' for one packet of data and 's' for continuous data. Type 's' to
stop the data flow.
9) To save the terminal setup go to File / Save As and save the settings.
When restarting the program the settings can be reloaded with File /
Load filename. Now actions 4 and 5 can be omitted.
Logging data continuously to a file using Microsoft TERMINAL.EXE
1) Run the Terminal program with the correct settings.
2) Set up the radiometer and send the command 's' via Terminal to
transmit data continuously from the radiometer.
3) Go to Transfers / Receive Text File. Enter filename for the stored data
(e.g. log1.txt).
4) On entering the file name, Terminal will now store all the readings
transmitted from the radiometer in a file log1.txt. The file is saved to
the computer by pressing STOP on the terminal screen.
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