AQ8602 RS-232C AC100 200VA - Datasheet Archive

 

AQ8602 Optical Fiber Strain/Loss Analyzer s Strain/loss distribution measuring instrument utilizing Brillouin scattering and

 

Optical Fiber Strain/Loss Analyzer AQ8602 AQ8602 Optical Fiber Strain/Loss Analyzer s Strain/loss distribution measuring instrument utilizing Brillouin scattering and Coherent detection (B/COTDR). s Strain and loss measurement in one unit. q High sample resolution Provides a sampling resolution of 5 cm. q Distance resolution: min. 2m Provides a high distance resolution of 2m in strain measurement. q High-speed measurement/data processing Ando's digital sampling technique has enabled the high-speed data processing and trace display. q Various analysis functions Strain distribution (average, scatter), Brillouin spectral distribution, loss distribution waveform and other analysis functions. q Various external interfaces External equipment (keyboard, printer, display, etc.) can be connected. q Data storage capabilities · Built-in 3.5-inch FDD (2HD) · Built-in hard disc q Large-size color LCD (9.4-inch) 9.4-inch color LCD screen assure superb readability. q Built-in high-speed printer Introduction The optical time domain reflectometer (OTDR) is extensively used to measure the loss distribution from the ends of optical fibers, and to detect line discontinuities. Under tensil strain, optical fiber strength degrades and eventually causes fiber breakage, but until now OTDRs have been unable to detect tensile strain without optical loss. For exactly this reason, high-precision strain measurement has been required in industries handling the manufacturing, installation and maintenance of optical fiber. The high-performance AQ8602 AQ8602 Optical Fiber Strain/Loss Analyzer provides all the functions needed for both Brillouin OTDR and Coherent OTDR applications. In addition to optical fiber loss and discontinuity measurements, it is also invaluable in preventive maintenance, such as prediction of breakage (life prediction). Features q High strain measurement accuracy: ±0.01% q BOTDR and COTDR are switchable The optical frequency translating and coherent detection techniques enable high sensitive measurement of strain distribution and loss distribution from one end of optical fiber. Easy fault locating of optical fiber is made possible as well. · Dynamic range in strain measurement: 20 dB (1µs pulsewidth) · Dynamic range in loss measurement: 32 dB (1µs pulsewidth) Applications s Evaluation of optical fiber cable installation process. s Maintenance and monitoring of an installed optical fiber cable. s Strain/loss distribution measurement at production of optical fiber cable. s Research and development of optical fiber cable. s Research of optical fiber sensing (temperature, tension, bending) 64 Fig. 1 Scattered light spectrum in the optical fiber Brillouin scattered light A typical scattered light spectrum in the optical fiber is shown in Fig. 1. Brillouin scattered light occurs by an interaction between a high-coherence incident light and an acoustic wave generated by the incident light in an optical fiber. The scattered light frequency is shifted from incident light frequency by an amount determined by the material. This frequency is called Brillouin frequency shift and it is given by the following equation (1). Input light (0) Intensity Rayleigh scattered light (0) Brillouin scattered light (0±) Raman scattered light (0-) Raman scattered light (0+) =(10+a few)GHz =(10+a few)THz Freq. B=2nVA/.(1) n : Refractive index VA : Acoustic wave velocity : Wavelength of incident light Fig. 2 Strain dependence of Brillouin frequency shift change Fig. 3 Temperature dependence of Brillouin frequency shift change Brillouin frequency shift change (MHz) Fig. 3. The strain/temperature dependence of the Brillouin frequency shift at 1.3µm and 1.55µm bands is tabulated in Table 1. Brillouin frequency shift change (MHz) Typical Brillouin frequency shift is ±13GHz (1.3µm band), ±11GHz (1.55µm band). The Brillouin frequency shift is in proportion to the change of strain/temperature as shown in Fig. 2 and 800 493[MHz/%] at =1.55µm 600 400 200 0 0 0.5 1.0 1.2 60 40 20 0 -20 -40 -60 -80 1[MHz/°C] at =1.55µm -60 -40 Strain (%) -20 0 20 40 60 80 Temperature (°C) Table. 1 The strain/temperature dependence of Brillouin frequency shift (UV coated optical fiber) Item 1.3µm band 1.55µm band Temp. (dB/dT) 1.22MHz/°C 1MHz/°C 581MHz/% 493MHz/% Strain (dB/d) Table. 1 shows that the strain measurement error caused by the temperature change of optical fiber is quite small (0.002%/°C). This means that the strain measurement error caused by 5°C of temperature B : T : : Brillouin frequency shift Temperature Strain change is equivalent to the measurement accuracy of this instrument (0.01%). Therefore, the strain added to the optical fiber can be calculated by measuring the Brillouin frequency shift. 65 Principle Fig. 4 AQ8602 AQ8602 basic configuration and signal waveform Light frequency shifter 0+S A02 + f Reference light source DFB-LD 0+S-B G G A01 Local light 0+S-B' Back scattered light Z L Strain Received level Coherent detector Receiver Signal processing Brillouin frequency where strain occurs differs from other places. 0 0 2L/V Time the pulsed light is varied, the Brillouin scattering at each frequency can be determined, yielding a spectrogram of Brillouin scattering. The peak reception level in this spectrogram is the Brillouin frequency shift (B(). The relation between the Brillouin frequency shift (B() and the tensile strain on the optical fiber is given by Expression (2). As a result, it is possible to determine the strain distribution from the Brillouin frequency shift (B() in the optical fiber axial direction. The basic configuration and signal waveform of the AQ8602 AQ8602 are indicated in Fig. 4. Pulsed light is input from the end of the optical fiber to be measured, and the return light (Brillouin scatter, Rayleigh scatter) detected by the coherent detection circuit. In Brillouin scattering the frequency is shifted from the input pulse by the Brillouin frequency shift B, which means that matching S (the difference between the light pulse 0+S and the local light frequency 0) to the Brillouin frequency shift B will allow detection of Brillouin light. If the optical frequency of B()=B(0)(1+C · ).(2) B() : Brillouin frequency shift with a strain B(0) : Brillouin frequency shift without a strain C : Strain coefficient : Strain Additionally, Rayleigh scattered light can be detected also when the frequencies of measuring pulsed light and local light agree. The AQ8602 AQ8602 is capable of measuring both the strain distribution (BOTDR) and the loss distribution (COTDR) by switching the frequency of the pulsed light accordingly. 66 Measurement example s Strain (average) distribution waveform: BOTDR MODE s Brillouin scattering distribution waveform (3D): BOTDR MODE The trace below is an example of a measurement of a 100km long SMF composed of four kinds of fiber (25km each) connected by fusion splices. The trace below is an example of a measurement of a 100km long SMF composed of four kinds of fiber (25km each) connected by fusion splices. H. scale: Distance (16km/div) V. scale: Strain (0.1%/div) Distance resolution: 100m H. scale: Distance (16km/div) V. scale: Scattering power (20dB/div) Z. scale: Optical frequency (100MHz/div) s Multi-waveform display of test results: BOTDR MODE s Loss distribution measurement waveform: COTDR MODE The trace below is an example of a measurement of a 100km long SMF composed of four kinds of fiber (25km each) connected by fusion splices. The trace below is an example of a measurement of a 100km long SMF. · · · · H. scale: 16km/div V. scale: 5dB/div Pulse width: 100ns Strain (average) waveform Strain (scatter) waveform Brillouin scattering spectrum Loss waveform 67 Specifications 1. Strain measurement mode (BOTDR mode) Trace display Strain distribution, Brillouin scattering spectrum, Brillouin scattering distribution Distance range (km) 10, 20, 40, 80, 160 Strain display range (%) Readout resolution (min.) -6.0 to +6.0 Distance 5cm Strain 0.001% Strain measurement range (%) Pulse width (ns) Dynamic range (dB) 3 20 Measurable distance 2) Distance resolution (m) 100 500 1000 8 1) 50 12 15 17 20 Approx. 55km Approx. 65km Approx. 80km 55 110 Approx. 25km Approx. 45km 3) 2 Strain measurement accuracy (%) 5 11 ±0.02 ±0.01 3) Minimum distance (X) from the rise point to true value (as indicated below) for optical fiber strain (average) distribution measurement waveforms, when specific strain is added from distance X0. Notes 1) At averaging times=216, strain measurement accuracy ±0.02% or less (optical fiber loss for strain noise width within ±0.02%). 2) With an optical fiber transmission loss of 0.25dB/km, optical fiber strain is measured for each pulse width, and the optical fiber distance determined for the ±0.02% strain measurement precision (216 average). Strain X Distance X0 2. Loss measurement mode (COTDR mode) Trace display Loss distribution Distance range (km) 2, 5, 10, 20, 40, 80, 160, 320 Loss display range (dB) Readout resolution (min.) 0 to 49 Distance 5cm Loss Pulse width (ns) Dynamic range (dB) Dead zone (m) 0.001dB 10 1) 20 50 100 500 1000 15 19 23 26 30 32 75 150 250 50 Note 1) At averaging times=218. 68 3. Overall Center wavelength (nm) 1550±20 Optical output power setting range (dBm) 0 to +25 (1dB step) Refractive index 1.00000 to 1.99999 (0.00001 step) 212 to 224 Averaging times setting range ±(2.0×10-5×measuring distance+0.7) Distance measurement accuracy (m) Number of sampling data 5,000 or 20,000 points Data storage 3.5-inch FDD (2HD), Built-in hard disc (340Mbyte) Display 9.4-inch color LCD 640×480 dots Interface Serial port: RS-232C RS-232C compatible printer (9 pin D-sub) 1) Centronics: Centronics compatible printer (25 pin D-sub) Video output: VGA compatible (6 pin D-sub) Keyboard: 6 pin DIN, PS/2 GP-IB Optical connector FC-PC Printer Built-in high-speed printer Power requirements Environmental conditions AC100 AC100 to 240V, 50/60Hz, 200VA 200VA max. Operating temperature BOTDR: 10°C to 40°C COTDR: 0°C to 40°C Note: Performance can be guaranteed in temperature range of 10°C to 40°C for COTDR Storage temperature -10°C to +50°C Humidity 85%RH or less (no condensation) Dimensions and mass Accessories Approx. 436(W)×240(H)×480(D)mm, approx. 20kg Instruction manual: 1 ea., power cord: 1 ea., printer paper: 2 ea. Note 1) Printer function at serial port are factory installed option. 69