1、Draft for Public Comment DC 94/709218 Document I Latest date for receipt of comments 31 October 1994 ACE/ 6/ 3 Our ref Date qrMAugust 1994 Sub-committee ACE/6/3 - Aerospace - Connectors DRAFT EUROPEAN STANDARD - AEROSPACE SERIES ELEMENTS OF ELECTRICAL AND OPTICAL CONNECTION - TEST METHODS - GENERAL
2、(prEN 2591 ) (Ist Revision to EN 2591) This draft is now available for public comment and your views and technical comments on it would be appreciated. If you have no specific comments to make but find it generally acceptable it would be helpful if you would notify us accordingly. Suggestions entail
3、ing revision of the text should indicate the preferred wording. Please quote the relevant clause number against any comment. The Co-ordination of the requirements of this draft with those of any related standards is of particular importance and you are invited to point out any areas where this may b
4、e necessary All comments should be sent to the Committee Secretary Mr F P Slot at the London-WmZ address below The comments received will be passed to the committee concerned for its consideration; no acknowledgement will normally be sent. Requests for further copies of this draft should be sent to:
5、 Sales Administration (Drafts), BSI, Mord Wood, Milton Keynes MK14 6LE. F(ur 0908 320856, Telex 825777 BSIMK G. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD Head office 2 Park Street, London W1A 2BS Telephone 071-629 9000 Telex 266933 BSILON G Fax 071-629 0506 825777 BSIMK
6、G Sales - the flame does not propagate to the other side of the support in the first twenty minutes. 3.8 Unless otherwise indicated, alternating voltage and current are indicated in root mean square values. Values of alternating voltage and current 3.9 Line data bus Pair of twisted wires, shielded,
7、having a specified impedance, a matched impedance at its two ends and used for data transport. 3.10 Branch line Section of twisted wires, shielded, with a specified impedance, which connects equipment to a bus line. 3.11 Line coupler Element of electrical or optical connection the purpose of which i
8、s to shunt the transmission signals from a bus line to equipment. 3.12 Line coupler, single Coupler consisting of one line and one branch. 3.13 Line coupler, double Coupler consisting of one line and two branches. 0417JN079413 Page 5 EN 2591:1994 3.14 In-line splice Permanent element of electrical c
9、onnection for Wo-wire cables. 3.1 5 Line termination End line component the purpose of which is to match the bus line to its characteristic impedance. 3.16 Branch termination End branch termination the purpose of which is to eventually replace equipment:. 3.17 Recovery Treatment of a specimen, after
10、 conditioning, so that the properties of the specimen may be stabilized before measuring. 3.18 Beam splitter Device for dividing an optical beam into two separate beams. 3.1 9 Extra optical attenuation caused by the insertion of an extra optical element into an optical system. Insertion loss (of an
11、optical element) 3.20 Launch angle The launch angle is the angle between the wave propagation vector of the incoming light and the normal vector of an optic fibre end face. 3.21 Multimode fibre A multimode fibre is an optical fibre having a large core diameter dimension in relation to the wavelength
12、 of the light, and in which a large number of modes can propagate. 3.22 Optical port The port which radiates or accepts optical power at the interface. 3.23 Fiber optic branching device A device possessing three or more optical ports which shares optical power among its ports in a predetermined fash
13、ion. 3.24 Patchord An assembly where the cable or fibre is terminated at each end with either a plug or socket connector. 3.25 Pigtail A pigtail is a short length of fibre between a component and a transmission fibre, often permanently secured to the component (LED, coupler, connection elements, .).
14、 3.26 Single mode fiber A single mode fibre is an optical fibre in which only one mode can propagate. 0417JN0794T3 94/TOC2 183c Page 6 EN 2591:1994 3.27 Passive coupler A passive coupler is a passive branching device in which power from one or more incoming optical ports is distributed to one or mor
15、e outgoing optical ports. 3.28 Tee coupler An optical fibre tee coupler is a passive coupler or combiner with three optical ports. 3.29 Return loss Light energy reflected back from discontinuities in a fibre optic link. 3.30 Light Launch System (L.L.S.) Device designed to create defined and repeatab
16、le light coupling conditions in a test setup. 3.31 Light Detection System (L.D.S.) Device designed to take repeatable measurements of light transmitted by a test setup, 3.32 Temporary joint Non permanent optical fibre connecting devices for use on equipment. 3.33 Terminator A non-reflective terminat
17、ion of an optical fibre. 3.34 Optical fibre - Core - Cladding - Primary coating - Refractive index profile - Step index fibre - Graded index fibre - Quasi-step index fibre - Core diameter - Cladding diameter - Concentricity error core/cladding - Non circularity of core - Non circularity of cladding
18、- Attenuation - Numerical aperture - Bandwith. For the following terms, see EN 3745-201 4 Standard test conditions 4.1 The test methods are drafted so that the test may be carried out either individually or included in a test sequence. This is why “if applicable“ has been added to the titles “Initia
19、l measurements“ and “Final measurements“. When the test is camed out individually, the measurements are applicable so that the effect of the test on the performances of the specimen can be evaluated. When the test is included in a test sequence, the initial and final states of the specimen shall be
20、checked at the beginning and the end of the test sequence. The initial and final measurements indicated in each test method are thus not applicable to each test. 4.2 Unless otherwise indicated in the test method, technical specification or product standard, the test conditions shall be as follows :
21、- temperature : (23 f 5) “C; - atmospheric pressure : 86 kPa to 106 kPa (860 mbar to 1060 mbar); - relative humidity : 45 % to 75 %. The temperature and humidity shall remain constant throughout a senes of measurements. 0417JN0794T3 Page 7 EN 2591:1994 Unless otherwise indicated in the technical spe
22、cification, the cables used for tests shall be in accordance with EN 2083 and EN 2084 or EN 2234 and EN 2346 and EN 3745. 4.3 Others 4.3.1 Fibre and preparation 4.3.1.1 General The aim of this paragraph is to give recommendations on preparing the ends of fibres, whether terminated or not. It is not
23、intended to describe a precise method for fibre end preparation ; instead it gives the information necessary to describe and quantify fibre and quality. This paragraph is applicable therefore to all tests which require the use of at least one optical interface of this type. It applies to all types o
24、f fibre, silica, plastic or a combination of these and other materials, irrespective of their diameter. 4.3.1.2 Parameters The following parameters define the quality of a fibre end : - surface condition; - perpendicularity of the optical face relative to the axis of symmetry of the fibre; - surface
25、 flatness. Surface condition (see figure 1) The face of the optical fibre shall not exhibit any nicking or lips and internal defects such as cracks Surface defects (hackle and mist zone) of the fibre core area shall not exceed 0,5 pm in size. A standard representation of the surface condition shall
26、be adopted in accordance with IS0 468. 1) Cracks made by a cleaving tool are acceptable if they don reach the core area. d R = 0.5 Cim Figure 1 Perpendicularity (see figure 2) The surface of the prepared fibre shall be perpendicular to the axis of symmetry of the fibre unless otherwise specified in
27、the product standard. The permitted defect shall be represented by a maximum permitted angle a. Figure 2 0417JN0794T3 Page 8 EN 2591:1994 Surface flatness (see figure 3) The surface of the prepared fibre shall be as flat as possible unless otherwise specified in the product standard. Concavity and c
28、onvexity shall be such that the maximum deviation between the highest and lowest points of the fibre surface envelope shall not exceed 3 pm. Figure 3 4.3.1.3 Methods Any method of fibre end preparation is acceptable provided that the parameters defined in 4.3.1.2 are within the range specified. NOTE
29、 : Depending on the recommendations of the fibre/cable/connector manufacturers, any of the following techniques may be used : cleaving, cutting, polishing. 4.3.1.4 Specimen examination and acceptance Any method, optical or otherwise, which enables defects of the size quoted in 4.3.1.2 to be assessed
30、, shall be acceptable. The methods may use systems which are as simple as a microscope with appropriate magnification for the measurement or as sophisticated as an interferometry test bench. A specimen shall be accepted when all the above parameters comply with the values defined in 4.3.1.2. 4.3.2 T
31、ermination cleaning 4.3.2.1 General To ensure satisfactory optical coupling performance between any two elements in a link, it is essential that both interfaces are clean. The aim of this paragraph is to give the type of information required for cleaning an optical face and to state where such infor
32、mation is available. 4.3.2.2 Required information The information required for cleaning the end of an optical fibre, whether terminated or not, essentially involves recommending the use of components and/or tools. A list shall therefore give the rcommended components, products and/or tools, those no
33、t on .the list not being allowed. These recommendations shall be specific to each fibre/cable/connector manufacturer and shall appear in the product standard. One requirement is however that where solvents are necessary, they shall not harm the ozone layer, and shall require minimum protection for t
34、he operator. 9417092 1 al)- d 041 7JN0794T3 Page 9 EN 2591 :1994 4.3.3 Light Launch System (L.L.S.) 4.3.3.1 General The launch conditions are essential for measuring opto-geometric parameters of an optical fibre or passive component, especially when it is a step index profile fibre for short distanc
35、e applications. The measurements to be made are very sensitive to the light launch conditions and therefore it is important that they should be clearly defined in order to provide repeatable measurements with a low spread. As well as being representative of the conditions of use or the equilibrium c
36、onditions, which are often unknown in the first case and unobtainable in the second, the launch conditions shall be related to the values of the characteristics parameters of the fibre itself, should be repeatable and easily configurable for the different types of fibres used. For these reasons, the
37、 launch conditions will be related to the theoretical values of the two main characteristics of the fibre, the core diameter (Qc = 2a) and the numerical aperture (NA). The launch is therefore made under a maximum angle and for a given spot diameter, with the power over the whole spot uniform at abou
38、t X YO, “X being yet to be defined. These maximum values are chosen as 90 % NAth and 90 % Qc to enable reproductible measurements to be made. These conditions do not represent real avionic system use, as different launch conditions will produce different results. 4.3.3.2 Measurement principle A typi
39、cal apparatus for maintaining stable launch conditions is shown in figure 4. This apparatus allows the image of part of a ribbon of tungsten to be produced (1) on the input face of the fibre, or fibre optic system to be measured. The diameter of the input beam as well as the maximum angle of the ray
40、s incident on the input face of the optical fibre are adjusted by means of two variable diaphragms (7 and 11) respectively. Monitoring of the diameter of the beam is made via a video screen fitted with a graticule which uses the light reflected from the input face of the fibre and the beam splitter
41、(8) to display the input face of the fibre and the spot diameter. The spot diameter can also be centred on the core. Adjustment of the maximum angle of launch is made by setting the aperture of the diaphragm (11) taking into account the distance between the diaphragm and the input face of the fibre
42、which has been secured after focusing on a video monitor. Once this distance has been defined, it can be reproduced, because it is obtained by focusing the input face of the fibre on the screen. The error caused by the depth of field of the objective lens is negligible and may be ignored. 4.3.3.3 Ex
43、ample of equipment The values indicated for component characteristics are those used for a laboratory prototype. 041 7JN0794T3 Page 10 EN 2591:1994 t z 3 ). E E 8 vi II L 54 E W II e- m N II u. - vi e s - d I w a c t, 2 n (5 E E 0- W vi - -1 I II 8 I u. ro C - f O vl +I O vi W 2 3 8 - E E E E 2 (5 I
44、I L E E W. O ln E E 00 O vi II e II 8 11- e- a -. . . . . . . . . . . “Clrncrvi Figure 4 041 7JN0794T3 Page 11 EN 2591:1994 . Processing 4.3.3.4 Method Display Switch on the apparatus 30 min before beginning the measurements. Incorporate the apparatus into the test system as instructed in the releva
45、nt test method. As required, position the input face of the optical fibre in the focal plane of the objective lens (10) in order to give a clear image of the face on the Video Display Unit (15). Adjust the field (7) and aperture (11) diaphragms to values of 4c and NA as required and begin the measur
46、ements in accordance with the method described in the test. 4.3.3.5 Special precautions Particular attention should be paid to the quality of the fibre end faces (see 4.3.1) as well as to the repeatability of the position of the fibre ends in relation to the corresponding components. 4.3.3.6 Documen
47、tation Nothing particularly relevant. 4.3.4 Light Detection System (LDS) 4.3.4.1 General The LDS has to be considered in connection with 4.3.3 and shall be harmonized with this system. The apparatus and the measurements shall be reproducible and easily configurable so that the different types of opt
48、ical fibres used may be measured. This is generally the case with the two main characteristics of the fibre, .e. the core diameter and the numerical aperture. The apparatus shall be adjustable for these two characteristics. The pickup shall be capable of detecting the whole optical output of the fib
49、re. This can be achieved, for instance, with an image, but also by scanning. 4.3.4.2 Measurement principle Figure 5 shows a possible apparatus with a photodiode. However, any other adequate apparatus, such as a CCD, may be used. As required, with the imaging system (1) the respective fibre end face will be collected and then, transmitted to the detector (2). The signal shall be computed by the processing system (3) and recorded or displayed as required (4). Feedback of the output signal can be used for direct comparison or adjustment of the input signal. 4.3.4.3 Example of equipement I (
