N3970A OPTICAL POWER METER Operating and Maintenance Guide
■ N3970A OPTICAL POWER METER SOURCE QUICK REFERENCE GUIDE ■ To remove interchangeable connector, move interface to mid position, and pull off adaptor. ■ To defeat auto power-off, hold POWER for 3 seconds at turn on until ON and perm are displayed. ■ To access hidden keypad, pull up display cover. Select POWER, Source, then: ■ To set reference, push Abs/Rel and hold Set Ref for 3 seconds (3 buzzer sounds). ■ To display reference, hold Abs/Rel, so Ref flashes. ■ To stop / start display update, push Hold.
■ 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.
■ CONTENTS 3 Care of your instrument 19 Introduction & applications Service and Support 4-5 Accuracy considerations 20-21 Safety Summary 6-7 Calibration, maintenance & instrument returns 22-24 Battery and external power Optical connector 8 9-10 How to use: Specifications - Definition of terms 25 Specifications and ordering information 26-28 Performance test 29-38 Getting started and turning on 11-12 Cleaning information 39-40 Autotest operation 13-14 Cleaning procedures 41 Power
■ SERVICE AND SUPPORT Any adjustment, maintenance, or repair of this product must be performed by qualified personnel. Contact your customer engineer through your local Agilent Technologies Service Center. You can find a list of local service representatives on the Web at: http://www.agilent.
■ INTRODUCTION AND APPLICATIONS The N3970A Optical Power Meter is used for field or laboratory testing of fiber optic systems at typically 850, 1300, 1310 and 1550 nm. It features superb measurement confidence, ease of use and reduced cost of ownership, and is for use by installers, technicians and engineers. Superior measurement confidence is achieved with a unique Total Uncertainty specification over the full temperature, measurement and connector range, and a NATA traceable calibration certificate.
■ 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.
■ 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.
■ SAFETY SUMMARY Initial Inspection Line Power Requirements Inspect the shipping container for damage. If there is damage to the container or Cushioning, keep them until you have checked the contents of the shipment for completeness and verified the instrument both mechanically and electrically. The Performance Tests give procedures for checking the operation of the instrument.
■ BATTERY AND EXTERNAL POWER The instrument is powered by two 1.5V dry batteries (Alkaline C) for an operating period of typically 250 hours or two 1.2V rechargeable batteries for an operating period of approximately 125 hours. 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.
■ OPTICAL CONNECTOR The optical port is mounted on a swivel, which allows the connector to be angled outwards for accessibility, and then pushed back and covered with the snap cover to provide dirt and drop protection. The other port can be used to store a spare interchangeable optical connector. 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.
■ OPTICAL CONNECTOR 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. 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.
■ GETTING STARTED AND TURNING ON This and following sections show you how to use your instrument: This instrument uses a menu driven keypad. The function of each button is shown on the display. Check that the correct accessories have been supplied, and an optical connector adaptor has been fitted. If you have any queries, call your supplier to resolve the situation. To access the optical connector, grasp a top corner of the instrument, and pull off the cover.
■ 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.
■ AUTOTEST OPERATION General Autotest features Operation For Autotest to function, all instruments involved in the test must be Agilent Handheld instruments with an Autotest function. Turn on the source and meter, and connect them with a test lead. On the light source, push AUTOTEST. This is all that is required to start Autotest operation on the power meter. The meter will automatically set to the correct λ and display absolute power in dBm. The display will alternate between wavelengths.
■ 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.
■ POWER METER OPERATION After instrument turn on, the meter will be calibrated at the last used λ. To change parameters, push POWER METER, then: To select a calibrated λ, push +/-. λ 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.
■ STORING & RECALLING READINGS There are various ways of storing and recording data, giving the user flexible ways of working. They are summarised here for your convenience. Storage of reference values: A separate reference is stored for each λ and can be recalled when the instrument is next turned on. 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.
■ STORING & R ECALLING READINGS The memory location is shown at the top right of the display. When storing data, the memory automatically increments to facilitate the collection of data on a job. 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. Read from any location: push RECALL, +/-. To display the relative value, push ABS/REL, and to display the reference, hold down ABS/REL.
■ 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. Instrument Jack Plug 9 Pin D connector for RS232 Wire 1 (screen) Body (Gnd) Pin 5 (Gnd) Wire 2 Ring (Tx) Pin 2 (Rx) Wire 3 Tip (Rx) Pin 3 (Tx) 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.
■ CARE OF YOUR INSTRUMENT ■ Follow the directions in this manual on cleaning optical connectors. ■ Limit the input optical power to no more than 5 dB overrange. ■ During storage and transport, keep the instrument in its carry case to protect against crushing, vibration, dust and moisture. ■ Clean the instrument using alcohol or other non solvent cleaning agents. Acetone or other active solvents may damage the case.
■ ACCURACY CONSIDERATIONS All measurements Optical connectors should be kept clean and in good condition. Due to emitter center λ uncertainty (eg 1310 +/- 20 nm), fiber attenuation may vary with different sources. This λ 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.
■ ACCURACY CONSIDERATIONS N3970A UM-1 21
■ CALIBRATION & MAINTENANCE Enabling / disabling ‘shift’ keypad & re-booting the microprocessor: See section on ‘getting started & turning on. 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.
■ CALIBRATION & M AINTENANCE ■ Measure and record the source power using the reference meter ■ 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. Maintenance CAUTION! Do not open unless the warranty has expired, you are authorised to do so, and you have a static protected work station.
■ CALIBRATION, MAINTENANCE & INSTRUMENT RETURNS ■ Hinged display cover removal can be done at this point. ■ 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. ■ 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.
■ 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).
■ SPECIFICATIONS & ORDERING INFORMATION Sensor Element Wavelength Range Calibration Wavelengths Power Range Maximum Input Power Uncertainty at reference conditions Total Uncertainty 3 Autotest sensitivity (typical) 4 Operating Time Applicable Fiber Type Optical Input Display Type Display Resolution Display Units 26 2 InGaAs 850-1650 nm 8501, 1300, 1310, 1550 nm +5 to –60 dBm (850 nm) +5 to –70 dBm (other wavelengths) +15 dBm ±0.13 dB (±3%) ±0.
■ 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.
■ SPECIFICATIONS & ORDERING INFORMATION ORDERING INFORMATION Instrument N3970A Optical Power Meter 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.
■ 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).
■ PERFORMANCE TEST Table 1 Required Equipment Instrument/Accessory Recommended Model Lightwave Multimeter Interface Module (one channel) Optical Head Laser Souce 1310/1550 nm 8163A 81618A Optical Attenuator 8156A#101 Connector Interfaces Connector Adaptors Singlemode Fiber 81000AI (3ea) 81000FA 81101AC 81101PC N3970-63251 FC Connector Adaptor for N3970A 81624A#C01 81654A Required Characteristics Alternative Models 8164A, 8166A 81619A 1305± 25nm 1550±30nm Short Term Stability<±0.
■ PERFORMANCE TEST Test Record Instrument Specification Results of the performance test may be tabulated on the Test Record provided at the end of the test procedure. It is recommended that you fill out the Test Record and refer to it while doing the test. Since the test limits and setup information are printed on the Test Record for easy reference, the record can also be used as an abbreviated test procedure (if you are already familiar with the test procedures).
■ PERFORMANCE TEST Performance 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. Total Uncertainty / Accuracy Test 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.
■ PERFORMANCE TEST 4. Switch on the instruments. 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 ■ Note the actual (displayed) wavelength of the laser source in the test report 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.
■ PERFORMANCE TEST 6. Measure the DUT. a. Make sure the N3970A (DUT) has warmed up b. Connect the attenuator output cable to the DUT as shown in figure below. Test Setup for the DUT Measurement 34 c. Select the correct wavelength on the DUT. d. Set the attenuator to its value for setting 1. ■ 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.
■ PERFORMANCE TEST Model N3970A Optical Power Meter Date Serial No. Ambient Temperature oC Options Relative Humidity % Firmware Rev.
■ PERFORMANCE TEST Description 1. Lightwave Multimeter Model No. 8163A 2. Light Source 1310/1550 nm 81654A 3. Optical Head 4. Optical Head Interface Module 81624A #C01 81618A 5. Optical Attenuator 8156A #101 6. 7. 8. 9. 10. Accessories Singlemode Fiber Connector Interfaces Connector Adaptors 36 #Product 1 81101AC 1 81101PC 3 81000AI 1 N3970-63251 1 81000FA Trace No Cal.
■ PERFORMANCE TEST Model N3970A Optical Power Meter Report No. Date Total Uncertainty/Accuracy Test Test Wavelengths = 1300 nm and 1310 nm Source Wavelength = Setting Number Reference (8163A Display) nm Attenuator Setting Minimum Spec. N3970A, DUT Maximum Spec. (-0.3 dB of Ref.) Measurement results (+0.3 dB of Ref.) 1 -3.00 dBm dB -3.30 dBm dBm -2.70 dBm 2 -20.00 dBm dB -20.30 dBm dBm -19.70 dBm 3 -30.00 dBm dB -30.30 dBm dBm -29.70 dBm 4 -50.00 dBm dB -50.30 dBm dBm -49.
■ PERFORMANCE TEST Model N3970A Optical Power Meter Report No. Date Total Uncertainty/Accuracy Test Test Wavelengths = 1550 nm Source Wavelength = Setting Number Reference (8163A Display) nm Attenuator Setting N3970A, DUT Maximum Spec. (-0.3 dB of Ref.) Measurement results (+0.3 dB of Ref.) 1 -3.00 dBm dB -3.30 dBm dBm -2.70 dBm 2 -20.00 dBm dB -20.30 dBm dBm -19.70 dBm 3 -30.00 dBm dB -30.30 dBm dBm -29.70 dBm 4 -50.00 dBm dB -50.30 dBm dBm -49.
■ CLEANING INFORMATION The following Cleaning Instructions contain some general 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 try, whenever possible, to use physically contacting connectors, and dry connections. Clean the connectors, interfaces, and bushings carefully after use.
■ CLEANING INFORMATION dampened with water, to clean the external case parts. Do not attempt to clean internally. 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.
■ CLEANING PROCEDURES Keep your dust and shutter caps on when your instrument is not in use. This should prevent it from getting too dirty. If you must clean such instruments, please refer the instrument to the skilled personnel of Agilent's service team. Preferred Procedure Use the following procedure on most occasions. 1. Blow away any dust or dirt with compressed air. If this is not sufficient, then a.
■ 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.
■ NOTES N3970A UM-1 43
■ NOTES 44
