1、 TIA DOCUMENT FOTP-47 Output Far-Field Radiation Pattern Measurement TIA-455-47-B (Revision of EIA/TIA-47-A) AUGUST 1992 TELECOMMUNICATIONS INDUSTRY ASSOCIATION The Telecommunications Industry Association represents the communications sector of Copyright Telecommunications Industry Association Provi
2、ded by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NOTICE TIA Engineering Standards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating int
3、erchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for their particular need. The existence of such Publications shall not in any respect preclude any member or non-member of TIA from manufacturing or selling prod
4、ucts not conforming to such Publications. Neither shall the existence of such Documents preclude their voluntary use by non-TIA members, either domestically or internationally. TIA DOCUMENTS TIA Documents contain information deemed to be of technical value to the industry, and are published at the r
5、equest of the originating Committee without necessarily following the rigorous public review and resolution of comments which is a procedural part of the development of a American National Standard (ANS). Further details of the development process are available in the TIA Engineering Manual, located
6、 at http:/www.tiaonline.org/standards/sfg/engineering_manual.cfm TIA Documents shall be reviewed on a five year cycle by the formulating Committee and a decision made on whether to reaffirm, revise, withdraw, or proceed to develop an American National Standard on this subject. Suggestions for revisi
7、on should be directed to: Standards Method C is a scan of the spatial transform of the angular intensity pattern. 1.2 Numerical Aperture This measurement method can be used to collect data that may be used in conjunction with FOTP-177 to determine the numerical aperture of graded-index multimode opt
8、ical fibers. 1.3 Hazards This method may employ laser sources and requires fiber alignment. Conform the design and operation of test equipment to the requirements of ANSI 2136.1 and/or 2136.2. 0 2. APPLICABLE DOCUMENTS Test, inspection, and safety requirements may include, but are not limited to, th
9、e following references : ANSI 2136.1 American National Standard for the Safe Use of Lasers ANSI 2136.2 American National Standard of the Safe Use of Optical Fiber Communication Systems Utilizing Luser Diode and LED Sources FOP-57 (EIA /TIA-455-S7A) FOT“-177 (TiA/EIA-4SS-1771) Optical Fiber End Prepa
10、ration and Examination Numerical Aperture Measurement of Graded-Index Optical Fibers 3. APPARATUS 3.1 Light Source Use a light source capable of producing an area of substantially constant radiance (variations of less than 10% in intensity across the fiber core region) on the endface of the test spe
11、cimen. It shall be stable in intensity and position over a time interval sufficient to perform the measurement to the precision desired. 1 A revision of this document is pending. Use -177 utii the publication of -17A. Copyright Telecommunications Industry Association Provided by IHS under license wi
12、th EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA TIA-455-47B 92 3234b00 0502499 3b EIA/TIA-455-47B Page 2 3.2 Input Optics Unless specified by another referencing FOTP, use a system of optical components to create a monochromatic, substantially constant ra
13、diance spot on the endface of the test specimen that complies with the following criteria: spectralwidth 100 nanometers full width half maximum (FWHM) illumination: 10% intensity variation (across the fiber core) numerical aperture: greater than that of the test specimen. Unless otherwise specified
14、in the Detail Specification, the center wavelength shall be 850 k 25 nm. Optical filters may be used to limit the spectral width of the source. 3.3 Provide support and alignment for the input end of the test specimen to allow stable and repeatable positioning without introducing significant fiber de
15、formation. Provide means of venfying the alignment of the endface. 3.4 Cladding Mode Stripper Remove light from cladding modes in the test specimen. Often the fiber coating is sufficient to perform this function. Otherwise, it wiU be necessary to use cladding mode strippers near both ends of the tes
16、t specimen. The fiber may be retained on the cladding mode strippers by placement of small weights, but take care to avoid microbending at these sites. 3.5 Angular Scan, Method A Refer to Figure 1 for a typical scan arrangement. Fiber Input End Support and Alignment RNICHED OUTPUT END SIDE VIEW Figu
17、re 1. Test Method A 3.5.1 Fiber Output End Support and Alignment Apparatus Support and align the output end of the test specimen such that the fiber endface is normal to and coincident with the axis of rotation of the optical detector. For example, a vacuum chuck mounted on X-Y-Z micropositioners ma
18、y be used, together with a microscopic fixture for aligning the fiber end. Other examples include a goniometer or stepper-motor-driven rotational stage. Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted witho
19、ut license from IHS-,-,-EIA/TIA-455-47B Page 3 0 3.5.2 Detection System Mechanics Provide means for rotating the optical detector to scan an arc sufficient to detect essentially all output radiation from the test specimen, and for recording the relative angular position of the detector with respect
20、to the output axis of the test specimen. (A calibrated goniometer is an example.) Ensure that the axis of rotation of this mechanism coincides with the endface of the test specimen. Ordinarily, the test specimen is horizontal, and the axis of rotation is vertical. 3.6 Angular Scan, Method B Refer to
21、 Figure 2 for a typical scan arrangement. CLAMP SAMPLE 1 TOP VIEW ZERO FiNISHED OUTPUT END - - - I *MOVABLE I 1 ARM BASE SIDE VIEW I Figure 2. Test Method B 3.6.1 Fiber Output End Support and Rotation Apparatus Support the test specimen such that the output endface is perpendicular to and coincident
22、 with the axis of rotation of the test specimen. This mechanism (a goniometer or precision rotating stage are examples) shaii rotate sufficiently to allow aii test specimen output radiation in the plane of rotation to sweep past the fixed detector. That is, the angular rotation must exceed the total
23、 angle of the test specimen output radiation. Provide means tL record the included angle formed by the specimen axis and the imaginary line between the detector and specimen end face. Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproductio
24、n or networking permitted without license from IHS-,-,-EIA/TIA-455-47B Page 4 3.7 Refer to Figure 3 for a typical scan arrangement. Scan of the Spatial Field Pattern, Method C A A 1 I I I v Ctnturcnnph) Detector /Scanner v Lens L2 (ilelay) (typical) V Test Sample Lens L1 (transform) Figure 3. Test M
25、ethod C 3.7.1 Provide means for supporting and aligning the test specimen output end to allow stable and repeatable positioning. 3.7.2 Create a spatial representation of the far field of the test specimen. For example, use a microscope objective or other well-corrected lens to obtain the Fourier tra
26、nsform of the fiber output near field pattern, and scan this pattern or its image with a pinhole aperture and detector to enable the far field intensity to be recorded. The size of the pinhole aperture shali be less than or equal to one-half the diffraction limit of the system: Fiber Output End Supp
27、ort Apparatus Far Field Transformation and Projection 1.22 Mhf 26 DI (1) where D = diameter of pinhole (p), h = wavelength (nm), f = transform lens focal length (mm), d = fiber core diameter (pm), M = magnification from back focal plane of transforming lens to scanning plane. and 3.7.3 Scanning Syst
28、em Provide means of scanning the far field pattern (or its image) with the pinhole aperture and detector. 3.7.4 System Calibration Perform a calibration to measure the conversion factor that relates the distance of movement of the scanning system, by whatever means employed to measure this movement,
29、 to the actual distance scanned in the back focal plane of the far field transforming lens. A pattern of known dimensions, carefully placed in the back focal plane of L1 (see Figure 3), can be used for this purpose. Copyright Telecommunications Industry Association Provided by IHS under license with
30、 EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA TIA-455-Y7E 72 W 3234b00 0502502 150 = EIA/TIA-455-47B Page 5 Determine tAae factor, y, that relates scan distance from the central axis in the spatial transformation plane to emission angle, 6, relative to th
31、e central axis as: y=fsin6 (2) where and NOTE: The sine factor is used because it is consistent with the microscope objectives corrected to conform with the Abbe sine condition. 3.7.5 Recording System Provide means to record detected intensity, E(y), as a function of scan position, y, and to correct
32、 the detected intensity as foliows: (3) y = distance from central axis, f = focal length of transform lens, LI, 8 = angle with respect to the central (optical) axis. I(e) = E(Y) COS e where I(6) is the angular intensity distribution as detected by an angular scan, and E(y) is the irradiance at dista
33、nce y from the axis of the spatial field pattern. (Y is the distance from the central axis, and 6 is the angle with respect to the central axis.) 3.8 Detector Use a detector that is linear within 5% over the range of intensity encountered. A pinhole aperture may be used to restrict the effective siz
34、e of the detector in order to achieve increased 3.8.1 Methods A and B. The distance, R, from the fiber endface to the detector or aperture must meet the requirement: 9 resolution. d2 R2- h where R = distance from endface to detector or aperture, (mm) and The detector or aperture size, D, can be dete
35、rmined for the angular resolution desired as: d = test specimen core diameter, (p), A = the measurement wavelength (nm). (4) D=$B 0.06 where D = the detector or aperture diameter, (pm), and A resolution of 10.5 degree is typically used. 3.8.2 Method C. R = fiber to detector or aperture distance (mm)
36、, 6 = angular resolution desired (degrees). (5) An appropriate detector or aperture size is given in equation 1 of 3.7.2. a Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA T
37、IA-455-47B 92 323lIbOO 0502503 O97 , EIA/TIA-455-47B Page 6 4. SAMPLING AND SPECIMENS 4.1 The test specimen length shall be in accordance with 4.2 or 4.3 unless modified by another FOTP. When this procedure is used in conjunction with FOTP-177,4.2 applies. 4.2 For short length measurements, the test
38、 specimen shaii be a representative specimen of fiber 2.0 f 0.2 meters (6.6 f 0.7 feet) in length, taken from the fuil length of fiber supplied. 4.3 For long length measurements, the test specimen shail be the length of fiber supplied. Report this test as a “long length measurement“, along with the
39、actual length tested. NOTE: The physical state of the long length of fiber may influence the measurement; therefore, the fiber deployment should reflect that of the intended application. Generally, care should be taken to avoid microbending in the specimen. 4.4 Prepare smooth, flat endfaces on the t
40、est specimen that are perpendicular to the fiber axis in accordance with FCYP-57. NOTE: The accuracy of the far field measurement is affected by endface angle. End angles less than 2 degrees are recommended. 5. PROCEDURE 5.1 Selection of Test Methods 5.1.1 Select one of the following methods to be p
41、erformed. (These methods are consistent and should produce the same result): 5.1.2 Method A - Angular Scan Fixed test specimen output end, rotating detector. Method B - Angular %an Rotating test specimen output end, fixed detector. Method C - Spatial Scan Scan of spatial field pattern. 5.1.3 5.1.4 5
42、.2 Test Procedure Use the following steps with any of the methods outlined in 5.1. 5.2.1 If specific cladding mode stripper devices are needed, remove any coating on the fiber in their vicinity. Place the test specimen ends in the support devices. Place the test specimen input end in the plane of, a
43、nd centered with respect to, the focused image of the constant- radiance spot. Position the output end as appropriate for the particular test method. Position the remainder of the test specimen to make microbending and mambending effects negligible. 5.2.2 Set the optical source to the desired wavele
44、ngth and spectral width. Report this data with the test results if these values are different than the default values given in 3.2. 5.2.3. Using the means provided for the test method used, scan the far field radiation pattern along a diameter and record intensity as a function of angular position.
45、6. Refer to Figure 4 as a typical example of the scanned far field pattern. CALCULATIONS OR INTERPRETATION OF RESULTS Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA TIA-455
46、-47B 92 3234600 0502504 T23 = EIA/TIA-455-47B Page 7 6.1 Normalize the scanned pattern to the peak intensity, and locate the angles at which the intensity is 5% of the maximum. Report 85 as half the angle between these points. See Figure 4. 6.2 Numerical aperture (NA). Refer to FmP-177 for the deter
47、mination of numerical aperture. The specimen length shall be according to 4.2. 6.3 Normalize the scanned pattern to the peak intensity, and locate the angles at which the intensity is 50% of the maximum. Report 8% as half the angle between these points. NOTE: A convenient notation for these results
48、is to use subscripts S and L to designate short and long length measurements, respectively. For example, ss, 8aL etc. Five Percent Intensity Angle, 85. Fifty Percent Intensity Angle, 0%. 1.0 - 0.9 - 0.8 - Relative 0.7 - in tensity 0.6 - 0.5 - 0.4 - 03 - o2 - 0.1 7 Figure 4. Typical Far Field Scan Pa
49、ttern 6.4 Radiation Pattern Measurement. If the radiation pattern is required, provide the entire normalized scan. Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA TIA-455-47B 92 3234600 0502505 bT D EIAfFIA-455-47B Page 8 7. 7.1 7.1.1 7.1.2 7.1.3 7.1.4 7.1.5 7.2 DOCUMENTATION Report the following information f
