Agilent Technologies Power Supply N3970A User Manual

N3970A OPTICAL POWER METER  
Operating and  
Maintenance Guide  
 
N3970A OPTICAL POWER METER SOURCE QUICK REFERENCE GUIDE  
To remove interchangeable connector, move interface to MANUAL OPERATION  
mid position, and pull off adaptor.  
To turn on and select wavelength, push: POWER, Power  
To defeat auto power-off, hold POWER for 3 seconds at  
Meter, -/+.  
turn on until ON and perm are displayed.  
To display linear mode, push dBm/W.  
To access hidden keypad, pull up display cover.  
Select POWER, Source, then:  
To display max/min values, push MAX/MIN repeatedly.  
Hold MAX/MIN to reset (3 buzzer sounds). .  
To set reference, push Abs/Rel and hold Set Ref for  
MEMORY  
3 seconds (3 buzzer sounds).  
Enter Power Meter or Autotest modes first  
While in Autotest mode, it is only possible to STORE.  
To display reference, hold Abs/Rel, so Ref flashes.  
To stop / start display update, push Hold.  
If a test tone is detected, meter will display Hz.  
AUTOTEST OPERATION  
To clear all memory, push both RECALL and CANCEL  
together for 3 seconds. clr will display.  
To store in next location, push STORE.  
No user action is required for meter to enter Autotest  
To change next store location, push SELECT -/+, SET.  
To recall, push RECALL -/+ to scroll through data.  
To exit memory display, push CANCEL.  
mode.  
Autotest: Push Autotest on source and wait a few  
seconds.  
ADDITIONAL AUTOTEST MEMORY OPERATION  
Can also push Autotest on meter for faster lock-on.  
To read or cancel memory, first exit Autotest mode, and  
To display one wavelength only, on the power meter  
push the left side of -/+ and again for the other wavelength.  
Push right side of -/+ (twice) to exit.  
enter Power Meter mode.  
Autotest memory: use -/+ to scroll wavelengths.  
Autotest remains for >8 seconds after signal loss, to allow  
quick connection change.  
Toexitautotest, removetestleadorturnoffsourcefor>8seconds.  
 
INTRODUCTION AND APPLICATIONS  
N3970A  
OPTICAL POWER METER  
Congratulations on your purchase of this instrument,  
which has been engineered to provide the best possible  
reliability, convenience and performance. To get the best  
use from your equipment and ensure its safe operation,  
please spend a few minutes to read this manual.  
1
 
CONTENTS  
Service and Support  
Introduction & applications  
Safety Summary  
3
4-5  
6-7  
8
Care of your instrument  
Accuracy considerations  
19  
20-21  
Calibration, maintenance & instrument returns 22-24  
Battery and external power  
Optical connector  
Specifications - Definition of terms  
Specifications and ordering information  
Performance test  
25  
26-28  
29-38  
39-40  
41  
9-10  
How to use:  
Getting started and turning on  
Autotest operation  
11-12  
13-14  
15  
Cleaning information  
Cleaning procedures  
Power meter operation  
Storing & recalling readings  
RS232 interface  
Disclaimer & warranty  
Notes  
42  
16-17  
18  
43-44  
BEFORE READING FURTHER, OPEN THE CONTROL PANEL PICTURE AT THE BACK OF THE MANUAL  
2
 
SERVICE AND SUPPORT  
Any adjustment, maintenance, or repair of this product must be Australia  
performed by qualified personnel. Contact your customer  
1 800 629 485  
(613) 9272 0749 (Fax)  
engineer through your local Agilent Technologies Service  
Center. You can find a list of local service representatives on the  
New Zealand  
Asia-Pacific  
0800 738 378  
64 4 495 8950 (Fax)  
(852) 3197 7777  
(852) 2506 9284 (Fax)  
If you do not have access to the Internet, one of these centers  
can direct you to your nearest representative:  
United States  
Canada  
1 800 452 4844  
1 877 894 4414  
(905) 206 4120 (Fax)  
Europe  
(31 20) 547 2323  
(31 20) 547 2390 (Fax)  
Japan  
(81) 426 56 7832  
(81) 426 56 7840 (Fax)  
Latin America  
(305) 269 7500  
(305) 269 7599 (Fax)  
N3970A UM-1  
3
 
INTRODUCTION AND APPLICATIONS  
The N3970A Optical Power Meter is used for field or laboratory High operational reliability & availability is achieved with 250  
testing of fiber optic systems at typically 850, 1300, 1310 and hour battery life, 3 year recommended re-calibration cycle,  
1550 nm. It features superb measurement confidence, ease of negligible warm up and no range-changing delays. Dark current  
use and reduced cost of ownership, and is for use by installers, offset is not required. An external power input is also provided.  
technicians and engineers.  
The combination of features enables reduced equipment  
Superior measurement confidence is achieved with a unique inventory, simpler training, shorter procedures, lower skill  
Total Uncertainty specification over the full temperature, levels and direct labour savings in many situations, combining  
measurement and connector range, and a NATA traceable to give lower cost of ownership.  
calibration certificate. The display hold and back light facilities  
The innovative optical connector port provides drop protection  
help acquire readings, and the flexible memory helps record  
during use, and is dust protected by a snap on cover. The  
your results  
interchangeable optical connector system is very versatile, and  
Autotest mode enables automatic l (wavelength) detection and easily disassembled for cleaning.  
attenuation measurement (in combination with an Autotest  
source). A single or dual l source and meter in Autotest mode  
automatically measure single or dual l attenuation in one  
direction.  
The simple user interface guides the operator through functional  
sequences, and a hidden keypad is used to access advanced  
features such as log/linear display, and memory functions.  
4
 
INTRODUCTION AND APPLICATIONS  
The tone detector is very sensitive, and is useful for fiber  
identification, and calibrating the modulation frequency of test  
tone sources.  
The instrument has shock absorbent corners, and a tough  
polycarbonate housing which has passed extensive drop testing.  
Typical applications  
Singlemode testing, with versatile interchangeable  
connectors.  
Telecom construction, maintenance, CATV, LAN and R&D  
applications.  
Measurements where traceability and documentation are  
required.  
Quality assurance and acceptance tests.  
Automated testing and reporting using optional Excel software.  
Test tone measurement & fiber identification.  
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5
 
SAFETY SUMMARY  
The following general safety precautions must be observed  
during all phases of operation, service, and repair of this  
instrument. Failure to comply with these precautions or with  
specific warnings elsewhere in this manual violates safety  
standards of design, manufacture, and intended use of the  
instrument. Agilent Technologies Inc. assumes no liability for  
the customer’s failure to comply with these requirements.  
CAUTION  
The CAUTION sign denotes a hazard. It calls attention to an  
operating procedure, or the like, which, if not correctly  
performed or adhered to, could result in damage to or  
destruction of part or all of the product. Do not proceed beyond  
a CAUTION sign until the indicated conditions are fully  
understood and met.  
Before operation, review the instrument and manual, for safety  
markings and instructions. You must follow these to ensure safe  
operation and to maintain the instrument in safe condition.  
CAUTION  
WARNING  
ƽ
The WARNING sign denotes a hazard. It calls attention to a  
procedure, practice or the like, which, if not correctly performed  
or adhered to, could result in injury or loss of life. Do not  
proceed beyond a WARNING sign until the indicated conditions  
are fully understood and met.  
The apparatus will be marked with this symbol when it is  
necessary for the user to refer to the instruction manual in order  
to protect the apparatus against damage.  
6
 
SAFETY SUMMARY  
Initial Inspection  
Line Power Requirements  
Inspect the shipping container for damage. If there is damage to The Agilent N3970A Power Meter operates at line power when  
the container or Cushioning, keep them until you have checked applied to the optional external power supply N3979A 9V DC  
the contents of the shipment for completeness and verified the  
Operating Environment  
instrument both mechanically and electrically.  
The Agilent N3970A Power Meter can be operated at  
temperatures between - 10°C and + 55°C and at relative  
humidity of <95%.  
The Performance Tests give procedures for checking the  
operation of the instrument. If the contents are incomplete,  
mechanical damage or defect is apparent, or if an instrument  
does not pass the operator’s checks, notify the nearest Agilent  
Technologies Sales/Service Office (see page 3).  
Storage and Shipment  
The Agilent N3970A Power Meter can be stored or shipped at  
temperatures between - 25°C and + 70°C and at relative  
humidity of less than 95%. Protect the module from  
temperature extremes that may cause condensation within it.  
WARNING  
To avoid any hazard, do not perform electrical tests when there  
are signs of shipping damage to any portion of the outer  
enclosure (covers, panels, and so on).  
REQUIREMENT COMPLIANCE  
WARNING  
You MUST return instruments with malfunctions to an Agilent  
Technologies Service Center for repair and calibration (see page 3).  
N 10149  
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7
 
BATTERY AND EXTERNAL POWER  
The instrument is powered by two 1.5V dry batteries (Alkaline C) for For operation of the instrument by external power use Agilent  
an operating period of typically 250 hours or two 1.2V AC adaptor N3979A (9V DC, 1.33 A,  
rechargeable batteries for an operating period of approximately  
).  
Use of the external power supply disconnects the batteries.  
125 hours.  
Ensure that the mains supply has the correct voltage rating and  
safety compliance as relevant. Do not use non-compliant or  
doubtful mains equipment.  
Do not use lithium batteries or other batteries with a nominal  
voltage greater than 1.8 V. The instrument will be damaged.  
When the batteries are low, the low-battery indicator is shown  
on the display. At this stage, there is approximately enough  
energy for another 30 minutes of use.  
For saving of energy the instrument automatically turns off after  
10 minutes without operation.  
For changing the battery, open the cover of the battery  
compartment at the base of the instrument, remove the batteries,  
insert new batteries (check polarity) and close the cover again.  
Rechargeable batteries must be charged by an external charger.  
8
 
OPTICAL CONNECTOR  
The optical port is mounted on a swivel, which allows the Optical connectors are precision components, and require care  
connector to be angled outwards for accessibility, and then in use:  
pushed back and covered with the snap cover to provide dirt and  
drop protection.  
Always clean the mating connector tip and ferrule before  
mating, using approved materials.  
The other port can be used to store a spare interchangeable  
optical connector.  
This instrument can be used with both PC and APC  
connector styles (unlike sources, which are factory  
To install the connector adaptor, align the locating slot on the  
side of the adaptor with that on the instrument connector, and  
push it on.  
configured for PC only ).  
The soft carry case enables the instrument to be stored  
without removing the test leads. This practice saves time,  
and is to be recommended.  
To remove the connector adaptor, move the connector port to it’s  
mid-way point (see dotted line on diagram at back of manual),  
and then pull off the adaptor. It is not possible to remove the  
adaptor in the ‘open’ or ‘shut’ positions. With some styles of  
connector, it is easier to pull off the adaptor with a test lead in  
place, since this gives better grip.  
When not in use, keep all test ports and connectors covered  
and away from dust.  
Do not touch connector tips with your fingers,  
since body oils and dirt can impair connector performance.  
Do not use damaged or incompatible connectors.  
Different styles of connector adaptor ( ST, SC, FC, ) can be  
easily fitted by the user.  
N3970A UM-1  
9
 
OPTICAL CONNECTOR  
meter inaccuracy may result. Preferred bare fiber adaptors  
consist of a connector with fiber retention device.  
If you work regularly with bare fibers, to avoid potential damage  
to the meter, it is generally preferable to use an alternative  
Cleaning  
The glass power meter interface does not make contact with the  
inserted connector: there is a slight air gap. Therefore it should  
not wear out, and only needs occasional cleaning.  
arrangement such as  
a
multimode pigtail with  
a
To clean the glass power meter interface: remove the  
interchangeable adaptor to access the glass interface, then use  
a sticky material such as ‘ Blu tac ‘ to dab the glass and remove  
any dirt. A soft brush, alcohol, or air can are also appropriate.  
Do not use anything hard that could scratch the glass.  
v-groove or mechanical splice.  
In this manual, refer to the sections on Cleaning Information  
and Procedures for further information.  
Bare fiber adaptors  
Bare fiber adaptors used with this power meter must achieve  
+
fiber eccentricity of _ 100 microns and end tolerance of  
+
_ 0.3 mm, relative to the ferrule end. Be careful not to scratch  
the detector interface when using adaptors, since permanent  
10  
 
GETTING STARTED AND TURNING ON  
This and following sections show you how to use your This instrument uses a menu driven keypad. The function of  
instrument:  
each button is shown on the display.  
Check that the correct accessories have been supplied, and an To access the optical connector, grasp a top corner of the  
optical connector adaptor has been fitted. If you have any instrument, and pull off the cover. The connector can be  
queries, call your supplier to resolve the situation.  
swivelled to improve access.  
Put in the batteries, or plug external power into the socket at the After instrument turn on, the instrument will perform a self-  
top of the instrument (see Battery and External Power section). calibration sequence, set the dark current adjustment, and then  
display absolute power in dBm at the previously set l . If HI or  
Push the green POWER button. The display will come on.  
If the battery is low, this will be indicated on the display.  
Pushing POWER again will turn the instrument off.  
LO are displayed, the input is out of range.  
The hidden keypad is accessed by pulling up the hinged display  
cover. The hidden keypad can operate in two modes. The  
second mode is accessed by SHIFT. Access to the second mode  
can be denied / permitted by typing the button sequence  
: POWER (turn on instrument), SHIFT, CANCEL, SET, SELECT,  
RECALL, STORE.  
To stop the instrument turning off 10 minutes after the last key  
press, hold POWER down for 3 seconds during turn-on. PERM  
on the display indicates that the unit will stay on permanently.  
To back light the display temporarily, select LIGHT. To back light  
continuously, hold down the button for 3 seconds. Use of the  
back light will drain the batteries faster.  
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11  
 
GETTING STARTED AND TURNING ON  
To disable or enable the buzzer, hold down SHIFT for 3 seconds.  
To add the carry strap: slip the end of the strap through the slit  
on the curved section at the back of the instrument, and secure  
the buckle.  
This instrument requires no warm up, and no user adjustment  
of dark current to achieve it’s specified performance.  
To learn how to use the instrument features, go to the next  
section.  
Should the instrument fail to turn on, the microprocessor may  
need re-booting. To do this, remove batteries and external  
power for at least 40 seconds. This will not lose stored data.  
12  
 
AUTOTEST OPERATION  
General Autotest features  
Operation  
For Autotest to function, all instruments involved in the test Turn on the source and meter, and connect them with a test lead.  
must be Agilent Handheld instruments with an Autotest On the light source, push AUTOTEST.  
function.  
This is all that is required to start Autotest operation on the  
The Autotest feature performs automated measurement (and power meter.  
automatic l detection) by data exchange between instruments,  
and requires minimal operator knowledge: turn the instrument  
on, connect a test lead, and select AUTOTEST on the source.  
Subsequent operation is automated, although some choices can  
be made for convenience.  
The meter will automatically set to the correct l and display  
absolute power in dBm. The display will alternate between  
wavelengths. To display only one l at a time, push +/-.  
You may also select AUTOTEST on the meter, which forces the  
meter into Autotest mode, with faster synchronisation in this  
mode (the source must be in Autotest mode). Push MENU to  
exit.  
Functionality is determined by the options fitted to the  
instrument(s) used. Autotest configures itself according to the  
options available, and carries out the most comprehensive test  
possible.  
The source power transmitted from the source is displayed on  
the left hand side of the display.  
Autotest remains synchronised for about 8 seconds, which  
enables the user to change optical connections without  
re-starting Autotest each time.  
Push ABS/REL to make the meter display relative power.  
The stored reference value(s) are displayed on the left hand side  
of the display.  
A light source transmits Autotest signals at one or two  
wavelengths to an appropriate power meter.  
To take a reference under Autotest, connect the source and  
N3970A UM-1  
13  
 
AUTOTEST OPERATION  
meter with a test lead. Set the source to Autotest mode, and then  
push SET REF on the meter for 3 seconds. This will store the  
reference at all relevant wavelengths.  
Either a ‘local’ or ‘remote’ reference can be stored.  
To exit Autotest mode, either disconnect the optical test lead, or  
exit Autotest mode on the light source for > 8 seconds.  
Refer also to manual sections on:  
Storing and recalling readings.  
14  
 
POWER METER OPERATION  
After instrument turn on, the meter will be calibrated at the last  
used l . To change parameters, push POWER METER, then:  
To select a calibrated l , push +/-. l is displayed on the top right  
side of the display.  
To display relative power, push ABS/REL. The display will  
show dB R.  
To store a new reference, push SET REFfor 3 seconds.  
To display the stored reference value, keep ABS/REL depressed.  
To change the dBm display between linear and log, access the  
hidden keypad and push dBm/W.  
If the meter detects a modulated signal, the display will change  
to show the actual measured modulation frequency in Hz,  
and if a standard tone is detected ( eg 270 Hz, 1 KHz,  
2 KHz ), a buzzer will sound. This is useful for fiber  
identification and signalling. The meter can also be used to  
check the actual modulation frequency of test sources.  
N3970A UM-1  
15  
 
STORING & RECALLING READINGS  
There are various ways of storing and recording data, giving the Storing & recalling readings using non-volatile memory  
user flexible ways of working. They are summarised here for  
your convenience.  
In Autotest, stored data includes absolute & relative values at all  
possible wavelengths.  
Storage of reference values: A separate reference is stored for  
each l and can be recalled when the instrument is next turned  
on.  
Note: To recall data, the unit must be in manual ‘power meter’  
mode.  
In manual mode, stored data includes absolute, relative and  
reference values.  
Display hold: To hold the display at it’s current value, push  
HOLD. This value can then be stored. Push HOLD again to  
continue updating the display.  
You can store, display or download up to 845 readings in non-  
volatile memory.  
Automatic recording of maximum & minimum limits: To display  
the minimum and maximum value over a period, access the  
hidden keypad and push MAX/MIN. The display will show the  
maximum and minimum values in sequence. Then push  
MAX/MIN for 3 seconds to re-start the recording process. This  
function re-sets automatically when instrument parameters are  
altered.  
Memory No  
Identifier  
Space  
1 - 199  
200 - 1990 (steps of 10)  
1 - 199  
200 - 1990 (steps of 10)  
1 - 199  
Total memory  
mem  
mem  
ID  
199  
179  
199  
179  
89  
ID  
mem / ID  
845  
16  
 
STORING & RECALLING READINGS  
The memory location is shown at the top right of the display.  
Read from any location: push RECALL, +/-. To display the  
relative value, push ABS/REL, and to display the reference, hold  
down ABS/REL.  
When storing data, the memory automatically increments to  
facilitate the collection of data on a job.  
Clear the whole memory: push CANCEL and RECALL together  
for 2 seconds. CLR will display.  
You can also go back and over-write particular records.  
After the data has been recorded, the entire memory can be  
cleared ready for the next job.  
Memory operating sequence  
Store data in next location: push STORE  
Store data starting at a particular location: push SELECT, +/-,  
SET, STORE  
The memory can not be read in Autotest mode. Exit Autotest  
before reading the memory.  
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17  
 
RS232 INTERFACE  
The connection details of the instrument, and connecting cables are as follows :  
Some (out of spec) serial ports need a 10 K resistor in the D connector across wires 1 & 2.  
Wire 1 (screen)  
Body (Gnd)  
Pin 5 (Gnd)  
Wire 2  
Ring (Tx)  
Pin 2 (Rx)  
Wire 3  
Tip (Rx)  
Pin 3 (Tx)  
Instrument Jack Plug  
9 Pin D connector for RS232  
The RS232 interface can be used to access and control the instrument from an external computer. All functions can be accessed  
remotely. See next pages for available software.  
The baud rate can be set to: 0.3, 0.6, 1.2, 2.4, 4.8, 9.6, 19.2, 38.4, 56 Kbaud. The default and printer baud rate is 9.6 Kbaud. To set the  
baud rate, on the hidden keypad, select -SHIFT- BAUD RATE, then -/+ to SET the rate, followed by set. At turn on, the default is  
restored.  
Local / remote modes  
The hidden keypad enables the user to lock out the front panel controls, by selecting LOCAL or REMOTE.  
18  
 
CARE OF YOUR INSTRUMENT  
Follow the directions in this manual on cleaning optical Clean the instrument using alcohol or other non solvent  
connectors.  
cleaning agents. Acetone or other active solvents may  
damage the case.  
Limit the input optical power to no more than 5 dB over-  
range.  
The instrument housing is made of tough Polycarbonate  
material with impact absorbing rubberised corner features,  
and is therefore drop resistant.  
During storage and transport, keep the instrument in its  
carry case to protect against crushing, vibration, dust and  
moisture.  
The instrument is resistant to normal dust and moisture,  
however it is not waterproof. If moisture does get into the  
instrument, dry it out carefully before using it again.  
Where possible, keep instrument away from strong sunlight.  
During prolonged storage, remove batteries to eliminate the  
possibility of acid leakage. Use only high quality sealed  
alkaline batteries.  
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19  
 
ACCURACY CONSIDERATIONS  
All measurements  
Most available laser sources ( except the N3974A Dual Laser  
Source ) are sensitive to reflections. Varying reflections can  
induce source instability of around 0.3 dB. This is very difficult  
to verify without a special test system, but can be a source of  
errors.  
Optical connectors should be kept clean and in good condition.  
Due to emitter center l uncertainty (eg 1310 +/- 20 nm), fiber  
attenuation may vary with different sources.  
This l uncertainty can also affect power meter calibration. This  
is significant with InGaAs in the 850 nm band, and absolute  
errors in the order of 1 dB are possible. This issue affects  
absolute power measurements. It does not significantly affect  
attenuation measurements where the meter was referenced to  
the same source.  
Polarisation changes create disturbances in both the optical  
system and measurement equipment. To reduce this, keep your  
system physically stable. Keep patch leads neat, coiled and  
stable.  
The N3970A Optical Power Meter has an InGaAs detector.  
Source power may drift: when you have finished a test, go back  
to the start position to check if source power is still within  
acceptable limits. It is worth noting that most sources only  
quote typical drift after warm up. Actual drift may of course be  
significantly worse, and will be very variable between  
instruments. The N3974A Dual Laser Source is unusual in  
offering maximum drift specifications, without warm up.  
20  
 
ACCURACY CONSIDERATIONS  
N3970A UM-1  
21  
 
CALIBRATION & MAINTENANCE  
Enabling / disabling ‘shift’ keypad & re-booting the To enable calibration mode, open the battery compartment, hold  
microprocessor: See section on ‘getting started & back the battery spring, remove the anti-tamper label, and insert  
turning on.  
a 0.1” pitch programming shunt. Manipulation of the shunt is  
easier with needle nose pliers. The meter will display ‘CAL’  
Calibration  
Before commencing calibration:  
Calibration can be readily performed without opening the  
instrument. Calibration is performed by setting up a singlemode  
laser source at a stable but non-critical power level between -10  
and -30 dBm, and adjusting the meter reading to the same value  
as that shown by a reference meter.  
Clean all connectors and the meter input ports very carefully  
Ensure all devices have been at stable room temperature for  
over an hour  
The source is fully warmed up at the l to be calibrated,  
The meter battery is good.  
Alternatively, known calibration constants can be  
re-entered directly without using other equipment. This is useful  
in case old calibration constants are to be put back, or the  
instrument memory has been corrupted.  
On the meter to be calibrated, record the existing calibration  
offsets as follows:  
Select POWER METER, +/- to set the wavelength, and  
MAX/MIN twice to display the offsets. Note them down.  
(you can also re-enter or adjust known offsets at this point)  
Required are laser light sources with accurate, calibrated  
wavelengths and good power stability, a power meter with  
appropriate calibrated wavelengths, singlemode test leads, an  
anti-tamper label, and a 0.1” programming jumper. Check the  
calibration certificates on your reference equipment, to ensure  
current validity.  
22  
 
CALIBRATION & MAINTENANCE  
Measure and record the source power using the reference Maintenance  
meter  
CAUTION! Do not open unless the warranty has expired, you are  
authorised to do so, and you have a static protected work  
station. Opening the unit will invalidate any warranty claim.  
There are no internal user adjustable components, fuses, or  
calibration features.  
Transfer the same power level to the meter to be calibrated,  
set MAX/MIN to display power, then +/- to adjust the  
reading to match the noted reference reading. Note: The  
optical power is measured only when entering this mode. It  
is not continuously updated.  
The optical sensor / connector assembly is not user serviceable.  
Opening the instrument:  
Set MAX/MIN to read and note the new stored calibration  
offsets, and then SET to store and exit, or CANCEL to  
abandon and exit  
Use static protected procedures  
Remove the batteries, and leave the battery cover open.  
Pull open the optical connector covers.  
Go back and check the source power with the reference  
meter, to ensure source drift is within limits.  
Place the instrument face down on a soft mat, and undo the  
When calibration is complete, remove the calibration shunt,  
and place an anti-tamper label over the hole in the battery  
compartment.  
6 screws in the rear housing.  
The instrument can now be gently pulled apart.  
The instrument will come into two halves joined by a ribbon  
cable. The optical section is located in the bottom half, with  
the microprocessor, supply, calibration constants and  
controls in the top half.  
Do no forget to update your calibration records, and  
schedule the next due date.  
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23  
 
CALIBRATION, MAINTENANCE & INSTRUMENT RETURNS  
Hinged display cover removal can be done at this point.  
Before returning equipment for repair or calibration, please  
check with your local Agilent Technologies Service Center  
(see page 3 Service and Support) to obtain a tracking number  
and shipping details. If the instrument is being returned for  
calibration, please include a purchase order.  
The ribbon connector can be disengaged to completely  
separate the instrument halves.  
Further dis-assembly from this stage should be easily  
apparent to a technician.  
Please state clearly the problem requiring attention.  
Re-assembly is the reverse of the previous procedure.  
Ensure that the ribbon cable connectors are properly  
secured so they cannot shake loose. This will be either a  
moulded rubber retainer, or adhesive tape.  
Please include your contact email, phone and fax number, and  
return shipping details.  
If the goods are under warranty, it would be helpful to include  
the original order / contract details.  
General electrical parameters are as follows: Vss to GND = 3V3,  
-Vss = -3V3, battery power down current about 0.2 mA, active  
current about 25 mA.  
If the goods are not under warranty, work will only proceed when  
a repair order has been issued. Please either include a repair  
order with the equipment, or request that a quotation be  
provided.  
24  
 
SPECIFICATIONS - DEFINITION OF TERMS  
Power Range  
The range of input powers for which the instrument can be used.  
Maximum Input Power  
The input power is not to be exceeded to avoid destroying the instrument.  
Uncertainty at  
reference conditions  
The uncertainty for the specified set of reference conditions, including all uncertainties  
in the calibration chain from the national laboratory to the test meter (connectors and  
patchcords must be absolutely clean and undamaged). Reference conditions are the  
conditions during the spectral responsivity calibration.  
Total Uncertainty  
The uncertainty for a specified set of operating conditions, including noise and drift  
(connectors and patchcords must be absolutely clean and undamaged).  
Autotest sensitivity  
The power level below which the Autotest does not work.  
N3970A UM-1  
25  
 
SPECIFICATIONS & ORDERING INFORMATION  
Sensor Element  
InGaAs  
Wavelength Range  
Calibration Wavelengths  
Power Range  
850-1650 nm  
8501, 1300, 1310, 1550 nm  
+5 to –60 dBm (850 nm)  
+5 to –70 dBm (other wavelengths)  
+15 dBm  
Maximum Input Power  
2
Uncertainty at reference conditions  
0.13 dB ( 3%)  
0.3 dB ( 7%) 2pW  
-40 dBm (850 nm)  
3
Total Uncertainty  
Autotest sensitivity (typical) 4  
-50 dBm (other wavelengths)  
250 hours  
9/125 µm to 62.5/125 µm  
Non-Contact, Removable Connector Adaptors  
LCD, 4 digits  
Operating Time  
Applicable Fiber Type  
Optical Input  
Display Type  
Display Resolution  
Display Units  
0.01dB, 3 digits in linear mode  
dB, dBm, nW, µW, mW  
26  
 
SPECIFICATIONS & ORDERING INFORMATION  
1: All specifications at 850 nm are typical.  
2: 23 3oK, -10 to –30 dBm, calibration wavelengths 2nm, fiber type standard SMF, connector type ceramic FC / PC, at day  
of calibration.  
3: includes uncertainty contributions due to: uncertainty at reference conditions, varying optical connector types, fiber types up  
to 62.5 µm core diameter and numerical aperture up to 0.3, operation within power range and within operating temperature range.  
4: Tested at room temperature, using an optical attenuator.  
Size:  
Weight:  
190 x 130 x 70 mm, 7.9” x 5.4 x 2.9  
500 gm, 1.1 lb. Shipping 2 Kg, 4.4 lb  
Operating / storage: -10 to 55°C / -25 to 70°C  
Power:  
2 alkaline C cells (7.6 A/hr) or external 9V DC with 2.5mm +ve pin.  
Selectable auto-off, low battery indicator, back lit display.  
100 - 9999 Hz 1%.  
Recording feature for stability testing.  
For setting advanced functions.  
Tone detection:  
Max / min:  
Hidden keypad:  
Damage level:  
Case:  
RS232:  
Calibration:  
Printing:  
> 5 dB above max reading.  
Polycarbonate, 1 meter drop tested.  
3.5 mm jack connector, 0.3 - 56 Kbaud, default 9.6 K.  
Performed without opening instrument.  
Not supported.  
N3970A UM-1  
27  
 
SPECIFICATIONS & ORDERING INFORMATION  
ORDERING INFORMATION  
Instrument  
N3970A Optical Power Meter  
Agilent service Part No.  
N3970-63240  
Description  
ST  
SC  
FC  
N3970-63246  
N3970-63251  
Standard accessories:  
Included with instrument: FC, ST, SC optical connector, manual,  
batteries, NATA traceable calibration certificate, carry strap,  
pouch, protective holster & RS 232 cable.  
Connector options: This instrument is equipped with  
interchangeable optical connector adaptors, and works with  
both PC and APC connectors.  
Optional accessories:  
Agilent Part No.  
Description  
Power Supply 9V DC  
N3979A  
Australian and international patents  
The N3974A Optical Power Meter is supplied with a straight  
contact output connector interface. To connect to the  
instrument, you must attach your connector interface (see list  
connector interfaces below) to the interface adaptor, then  
connect your cable.  
28  
 
PERFORMANCE TEST  
The procedures in this section test the performance of the  
instrument. The complete specifications to which the Agilent  
N3970A Optical Power Meter is tested are given on pages 26-28.  
All tests can be performed without access to the interior of the  
instrument. The test equipment given corresponds to tests  
carried out with Diamond HMS-10 connectors and FC/PC  
connectors on the DUT (devise under test).  
Equipment Required  
Equipment required for the performance test is listed in the table  
on page 30. Any equipment that satisfies the critical  
specifications of the equipment given in the table may be  
substituted for the recommended models.  
N3970A UM-1  
29  
 
PERFORMANCE TEST  
Table 1 Required Equipment  
Instrument/Accessory  
Recommended  
Model  
Required  
Characteristics  
Alternative  
Models  
Lightwave Multimeter  
Interface Module (one  
channel)  
8163A  
81618A  
8164A, 8166A  
81619A  
Optical Head  
81624A#C01  
81654A  
Laser Souce 1310/1550 nm  
1305 25nm  
81657A or  
1550 30nm  
81650A & 81651A  
or  
Short Term Stability< 0.005 dB  
81655A and 81656A  
Optical Attenuator  
8156A#101  
Attenuation >50 dB  
Return Loss >26 dB  
Repeatability < 0.01 dB  
Connector Interfaces  
Connector Adaptors  
Singlemode Fiber  
81000AI (3ea)  
81000FA  
81101AC  
81101PC  
N3970-63251  
81101FC  
FC Connector Adaptor for  
N3970A  
Note: Instead of 8163A, 81618A, 81624A #C01 and 81654A also the older but discontinued equipment 8153A, 81533B, 81524A  
#C01 and 81554SM together with 81210LI #011 and 81310LI # 011 can be used.  
30  
 
PERFORMANCE TEST  
Test Record  
Instrument Specification  
Results of the performance test may be tabulated on the Test Specifications are the performance characteristics of the  
Record provided at the end of the test procedure. It is instrument that is certified. These specifications, listed on page  
recommended that you fill out the Test Record and refer to it 26, are the performance standards or limits against which the  
while doing the test. Since the test limits and setup information Agilent N3970A can be tested.  
are printed on the Test Record for easy reference, the record can  
also be used as an abbreviated test procedure (if you are already  
Any changes in the specifications due to manufacturing  
familiar with the test procedures). The Test Record can also be  
changes, design, or traceability to the National Institute of  
used as a permanent record and may be reproduced without  
Standards and Technology (NIST), will be covered in a manual  
written permission from Agilent Technologies.  
change supplement, or revised manual. Such specifications  
supersede any that were previously published.  
Test Failure  
If the Agilent N3970A fails any performance test, return the  
instrument to the nearest Agilent Technologies Sales/Service  
Office for repair (see page 3).  
N3970A UM-1  
31  
 
PERFORMANCE TEST  
Performance Test  
Total Uncertainty / Accuracy Test  
The performance test given in this section includes the  
Total Uncertainty/Accuracy Test. Perform each step in the  
order given, using the corresponding test equipment.  
1. Make sure that you satisfy the environmental conditions.  
2. Make sure all your connectors are clean.  
3. Connect the equipment as shown in figure below.  
Note Make sure that all optical connections are dry and  
clean. DO NOT USE INDEX MATCHING OIL. For  
cleaning, use the cleaning instructions given in "Cleaning  
Procedures" on page 41.  
Make sure that all patchcords are fixed to the table so that  
they won't move during measurements.  
Make sure that the ambient conditions are in the  
following ranges:  
temperature  
Relative humidity 45 to 75 %  
23ºC 3K  
Test setup for the Uncertainty Test Reference Measurement  
Make sure that all Patchcords are fixed to the table and  
won't move during measurements.  
32  
 
PERFORMANCE TEST  
4. Switch on the instruments.  
until PERM is shown in the display.  
Set the DUT to "dBm"  
f. Make sure that all the instruments are warmed up.  
5. Make the reference measurement.  
a. Switch on the lightwave multimeter.  
b. Configure the laser source.  
Set the laser source attenuation to 0 dB  
Set the wavelength to 1310 nm  
a. Enable the laser source and the attenuator output.  
b. Change the attenuation of the attenuator until the optical  
power meter displays -3.00 dBm.  
Note the actual (displayed) wavelength of the laser source in  
the test report  
Note In some cases the laser source will not be powerful  
enough to give -3.00 dBm. In such case, set the attenuator to  
0 dB and correct the appropriate values in the test report.  
Note the setting of the attenuator for setting 1 in the test report  
c. Change the attenuation of the attenuator until the optical  
power meter displays -20.00 dBm.  
Note the setting of the attenuator for setting 2 in the test report  
d. Change the attenuation of the attenuator until the optical  
power meter displays -30.00 dBm.  
Note the setting of the attenuator for setting 3 in the test report  
e. Change the attenuation of the attenuator until the optical  
power meter displays -50.00 dBm.  
c. Switch on the attenuator.  
Set the wavelength to the wavelength of the laser source  
in the test report  
d. Configure the optical head and interface module.  
Set the unit to dBm  
Set the averaging time, T, to 100 ms  
Set AUTO ranging on  
Set the wavelength to the wavelength of the laser source  
With the laser source and attenuator disabled, zero  
the power meter  
e. Switch on the N3970A (DUT) for permanent operation, by  
holding the POWER key down for 3 seconds during turn-on  
Note the setting of the attenuator for setting 4 in the test report  
N3970A UM-1  
33  
 
PERFORMANCE TEST  
6. Measure the DUT.  
c. Select the correct wavelength on the DUT.  
d. Set the attenuator to its value for setting 1.  
a. Make sure the N3970A (DUT) has warmed up  
b. Connect the attenuator output cable to the DUT as  
shown in figure below.  
Note the displayed power level of the DUT in the test record  
e. Set the attenuator to its value for setting 2.  
Note the displayed power level of the DUT in the test record  
f. Set the attenuator to its value for setting 3.  
Note the displayed power level of the DUT in the test record  
g. Set the attenuator to its value for setting 4.  
Note the displayed power level of the DUT in the test record  
7. Repeat from list item 4 to list item 6 at 1550 nm.  
Test Setup for the DUT Measurement  
34  
 
PERFORMANCE TEST  
Model N3970A Optical Power Meter  
Date  
o
Serial No.  
Options  
Ambient Temperature  
Relative Humidity  
Line Frequency  
C
%
Firmware Rev.  
Hz  
Test Facility  
Customer  
Report No  
Performed by  
Special Notes  
N3970A UM-1  
35  
 
PERFORMANCE TEST  
Description  
1. Lightwave Multimeter  
Model No.  
8163A  
Trace No  
Cal. Due Date  
2. Light Source 1310/1550 nm  
81654A  
3. Optical Head  
81624A #C01  
81618A  
4. Optical Head Interface Module  
5. Optical Attenuator  
8156A #101  
6.  
7.  
8.  
9.  
10.  
Accessories  
#Product  
Singlemode Fiber  
1 81101AC  
1 81101PC  
3 81000AI  
Connector Interfaces  
Connector Adaptors  
1
N3970-63251  
1 81000FA  
36  
 
PERFORMANCE TEST  
Model N3970A Optical Power Meter  
Total Uncertainty/Accuracy Test  
Test Wavelengths = 1300 nm and 1310 nm  
Report No.  
Date  
Source Wavelength =  
nm  
Setting  
Number  
Reference  
(8163A Display)  
Attenuator  
Setting  
Minimum Spec.  
(-0.3 dB of Ref.)  
N3970A, DUT  
Measurement results  
Maximum Spec.  
(+0.3 dB of Ref.)  
1
2
3
4
-3.00 dBm  
-20.00 dBm  
-30.00 dBm  
-50.00 dBm  
dB  
dB  
dB  
dB  
-3.30 dBm  
dBm  
-2.70 dBm  
-19.70 dBm  
-29.70 dBm  
-49.70 dBm  
-20.30 dBm  
-30.30 dBm  
-50.30 dBm  
dBm  
dBm  
dBm  
Measurement Uncertainty  
dB  
N3970A UM-1  
37  
 
PERFORMANCE TEST  
Model N3970A Optical Power Meter  
Report No.  
Date  
Total Uncertainty/Accuracy Test  
Test Wavelengths = 1550 nm  
Source Wavelength =  
nm  
Setting  
Number  
Reference  
(8163A Display)  
Attenuator  
Setting  
Minimum Spec.  
(-0.3 dB of Ref.)  
N3970A, DUT  
Measurement results  
Maximum Spec.  
(+0.3 dB of Ref.)  
1
2
3
4
-3.00 dBm  
-20.00 dBm  
-30.00 dBm  
-50.00 dBm  
dB  
dB  
dB  
dB  
-3.30 dBm  
dBm  
-2.70 dBm  
-19.70 dBm  
-29.70 dBm  
-49.70 dBm  
-20.30 dBm  
-30.30 dBm  
-50.30 dBm  
dBm  
dBm  
dBm  
Measurement Uncertainty  
dB  
38  
 
CLEANING INFORMATION  
The following Cleaning Instructions contain some general Safety Precautions  
safety precautions, which must be observed during all phases of  
cleaning. Consult your specific optical device manuals or  
guides for full information on safety matters.  
Please follow the following safety rules.  
Do not remove instrument covers when operating.  
Ensure that the instrument is switched off throughout the  
cleaning procedures.  
Use of controls or adjustments or performance of procedures  
other than those specified may result in hazardous radiation  
exposure.  
Make sure that you disable all sources when you are cleaning  
any optical interfaces.  
Under no circumstances look into the end of an optical  
device attached to optical outputs when the device is  
operational. The laser radiation is not visible to the human  
eye, but it can seriously damage your eyesight.  
To prevent electrical shock, disconnect the instrument from  
the mains before cleaning. Use a dry cloth, or one slightly  
Please try, whenever possible, to use physically contacting  
connectors, and dry connections.  
Clean the connectors, interfaces, and bushings carefully after use.  
If you are unsure of the correct cleaning procedure for your  
optical device, we recommend that you first try cleaning a  
dummy or test device.  
Agilent Technologies assume no liability for the customer's  
failure to comply with these requirements.  
For more information about Cleaning Instruments, please  
consult the Pocket Guide "Cleaning Procedures for Lightwave  
Test and Measurement Equipment" (Agilent P/N 5963-3538F).  
If you do not have a copy of this pocket guide, Agilent will  
provide you with one free of charge.  
N3970A UM-1  
39  
 
CLEANING INFORMATION  
dampened with water, to clean the external case parts. Do not inaccurate and non-repeatable. Cleaning is, therefore, an  
attempt to clean internally.  
essential yet difficult task. Unfortunately, when comparing most  
published cleaning recommendations, you will discover that  
they contain several inconsistencies. In this section, we want to  
suggest ways to help you clean your various optical devices,  
and thus significantly improve the accuracy and repeatability of  
your lightwave measurements.  
Do not install parts or perform any unauthorised modification to  
optical devices.  
* Refer servicing only to qualified and authorised personnel.  
Why is it important to clean optical devices ?  
In transmission links optical fiber cores are about 9 µm  
(0.00035") in diameter. Dust and other particles, however, can  
range from tenths to hundredths of microns in diameter. Their  
comparative size means that they can cover a part of the end of  
a fiber core, and as a result will reduce the performance of your  
system.  
Furthermore, the power density may burn dust into the fiber and  
cause additional damage (for example, 0 dBm optical power in  
a single mode fiber causes a power density of approximately 16  
million W/m2). If this happens, measurements become  
40  
 
CLEANING PROCEDURES  
Keep your dust and shutter caps on when your instrument is not 1. Moisten a new cotton swab with isopropyl alcohol.  
in use. This should prevent it from getting too dirty. If you must  
2. Clean the interface by rubbing the cotton swab over the  
clean such instruments, please refer the instrument to the  
surface using a small circular movement.  
skilled personnel of Agilent's service team.  
3. Take a new, dry soft tissue and remove the alcohol, dissolved  
sediment and dust, by rubbing gently over the surface using  
Preferred Procedure  
a small circular movement.  
Use the following procedure on most occasions.  
4. Blow away any remaining lint with compressed air.  
1. Blow away any dust or dirt with compressed air.  
If this is not sufficient, then  
a. Clean the interface by rubbing a new, dry cotton swab  
over the surface using a small circular movement.  
b. Blow away any remaining lint with compressed air.  
Procedure for Stubborn Dirt  
Use this procedure when there is greasy dirt on the interface,  
and using the procedure for light dirt is not sufficient. Using  
isopropyl alcohol should be your last choice for recessed lens  
interfaces because of the difficulty of cleaning out any dirt that  
is washed to the edge of the interface.  
N3970A UM-1  
41  
 
DISCLAIMER & WARRANTY  
Information in this manual is given in good faith for the benefit  
of the user. It cannot be used as the basis for claims against  
Agilent Technologies or its representatives, if accidental  
damage or inconvenience results from use or attempted repair  
of the equipment.  
Agilent Technologies products are guaranteed against defective  
components and workmanship for a period of 3 years from the  
date of delivery, unless specifically stated in the original  
purchase contract or agreement. This warranty excludes optical  
connectors or incorrect use. Opening the instrument will  
invalidate the warranty. Liability is limited solely to repair of the  
equipment.  
42  
 
NOTES  
N3970A UM-1  
43  
 
NOTES  
44  
 

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