1、FED-STD-3 76 W 7777377 0004373 5 W FeXStd. NO. 3 21 MARCH 1951 FEDERAL STANDARD COLORS, AERONAUTICAL LIGHTING Thia standard was approved on the above date by the Commissioner, Federal Sup ply Service, General Services Adntinzstratzon, for the use of all Federal agencies. 1. SCOPE AND CLASSIFICATION
2、1.1 Scope.-This standard defines the color requirements for aeronautical lights, gives the requirements for primary standard fil- ters, and describes techniques of inspection. 1.2 Classification. 1.2.1 Catego7.ies. - Colors shall be fur- nished in the following categories as speci- fied : Category 1
3、.-Aviation colors : Aviation red. Aviation yellow. Aviation green. Aviation blue. Aviation white. Category 11.-Identification colors : Identification red. Identification yellow. Identification green. Identification lunar-white. Category 111.-Signal colors : Signal red. Signal green. 1.2.1.1 Purpose
4、of category I, aviation col- ors.-Aviation colors are intended for high- intensity long-range signal lights in which the primary consideration is that the light be seen, the secondary consideration is that its color be identified. If aviation colors are used in situations requiring positive color id
5、enti- fication, relatively few colors are used at a time. For example, aviation white is not in- tended to be distinguishable from aviation yellow unless it is in juxtaposition with it. On these accounts, the aviation colors are defined in such a way that they may be produced from incandescent lamps
6、 by means of ware of relatively high luminous trans- mittance. Since such high transmittance re- quires that the spectral band transmitted must be relatively broad, aviation colors must necessarily be perceived as relatively unsaturated. 1.2.1.2 Purpose of category II, identification colors.-Identif
7、ication colors are intended for signal lights in which the primary object is the identification of the color. Each of the identification colors usually must be distin- guishable from each of the remaining identi- fication colors at ranges not much less than the maximum. The definitions of identifica
8、- tion colors therefore provide for the maxi- mum chromatic distinction obtainable from ware transmitting relatively narrow spec- tral bands. 1.2.1.3 Purpose of categorg III, signal col- ors.-Signal colors are intended for purposes, such as daytime signaling, generally requir- ing properties interme
9、diate between those of aviation and identification colors. Note 1-Signal-green chromaticity require- ments are the same as those of identification green ; the transmittance requirements are based upon the use of plastic ware. -. 1.2.2 Grades. - This standard covers the transmittance requirements of
10、four grades of light-transmitting ware: A, B, C, and D, in descending order of transmittance ;IS specified in table I. flS DOCUMENT CONTAINS PAGES, 901 689-5 I-( 189) I . ;c- 1 U Licensed by Information Handling Services_ FED-STD-3 76 W 7779777 OOOL1L74 7 W Fed. Std. No. 3 1.2.2.1 Purpose of grade A
11、.-Grade A is to be used only when the highest possible transmittance is essential. 1.2.2.2 Purpose of grade B.-Grade B is suitable for pressed ware of a uniform thick- ness of not more than 6 millimeters (0.2 inch) throughout the working area, such as position-light and identification-light covers,
12、smooth-obstruction-light covers, and iters for carrier approach lights. 2.2.5 Rectangular Uniform-Chromaticitp- Scale Coordinates, F. C. Breckenridge and W. R. Schaub, Journal of the Optical Society of America, volume 29, page 370 (1939). 2.2.6- Tables for Transforming Chromatic- ity Coordinates fro
13、m the ICI System to the RUCS Sjystem, National Bureau of Standards Letter Circular LC897 (1948). 3. DEFINITIONS 3.1 General definitions.-Each of the fol- 12*2.3 Of grade e is lowing technical terms is used in this stand- in which the term is defined suitable for such blown ware as code-beacon and co
14、ntact-light filters. ard in the in this section. 1.2.2.4 Purpose of grade D.-Grade D is suitable for thick-sectioned ware such as beacon lenses, including course lights, ob- struction-light lenses, and contact-light lenses and also for filters for airport approach lights. 2. APPLICABLE SPECIFICATION
15、S AND REFERENCE PUBLICATIONS 2.1 Specifications.-There are no Federal specifications applicable to this standard. 2.2 Reference publications.-The follow- ing publications contain basic material per- tinent to this standard. 2.2.1 Psychophysics of Color, by Commit- tee on Colorimetry, Journal of the
16、Optical Society of America, volume 34, page 245 (1944). 2.2.2 Quantative Data and Methods for Colorimetry, by Committee on Colorimetry, Journal of the Optical Society of America, volume 34, page 633 (1944). 2.2.3 1931 ICI Standard Observer and Co- ordinate Szjstem for Colorimetry, D. B. Judd, Journa
17、l of the Optical Society of America, volume 23, page 359 (1933). 2.2.4 Colorimetrg, National Bureau of Standards Circular 478 (1950). 2 3.1.1 Standard observer.-The standard ob- server and coordinate system is that adopted by the International Commission on Illumi- nation (ICI) at its Eighth Session
18、 at Cam- bridge, England, in 1931. (See 2.2.1, 2.2.2, 2.2.3, and 2.2.4.) This standard observer re- fers essentially to cone vision. Darkness adaptation does not prevent correct recogni- tion of colored lights if intense enough to be seen by a light-adapted observer. 3.1.2 Chromaticity. - Chromatici
19、ty of a color is a combined attribute determined by its dominant wavelength (3.1.3) and excita- tion purity (3.1.4). Chromaticity limits are usually given in terms of coordinates (x, y) in the ICI standard coordinate system. 3.1.3 Dominant wavelength. - Dominant wavelength of a color is that wavelen
20、gth of spectrum light which, when combined with neutral light in suitable proportions, matches the color. Neutral light is light for which the chromaticity coordinates are x equals 0.333 and y equals 0.333. Colors of the same dominant wavelength are perceived under ordinary viewing conditions as of
21、nearly the same hue. The chromaticity coordinates of colors described as having the same dominant wavelength in the ICI standard coordinate system lie on a straight line passing through the neutral point and the point on the spec- trum locus which represents the spectrum component. .-A 8 Licensed by
22、 Information Handling ServicesFED-STD-3 76 3.1.4 Excitation purity.-.Excitation puri- ty is the ratio of the distance on the ICI standard chromaticity diagram between the neutral point and the sample point to the distance in the same direction between the neutral point and the spectrum locus or the
23、purple boundary. Excitation purity may be indicated by the word “purity“ alone (see 3.1.6). 3.1.5 Hue.-Hue is that attribute of a color which determines whether the color is per- ceived as red, yellow, green, blue, purple, or as an intermediate color. Colors which have no hue are called neutral colo
24、rs. A great variety of qualities of light are perceived as neutral under various circumstances. In gen- eral, colors represented in the region of the .chromaticity diagram near x equals 0.333 and y equals 0.333 may be considered as neutral colors under ordinary conditions of observation. 3.1.6 Satur
25、ation.-Saturation is that attri- bute of a color which determines whether the color is perceived as greatly or slightly different from neutral. Colors of low satura- tion have less prominent hue. If dominant wavelength and luminance of a color be held constant, the saturation of the perceived color
26、is found to correlate with purity; that is, if the purity of the color is low, it will be perceived to haue low saturation, and if it is of high purity, it will yield a highly saturated color perception. To make sure that the hue of a signal is sufficiently dis- tinct, it is usually sufficient to sp
27、ecify a minimum value for the purity of its color. 3.1.7 Luminance. - Luminance (formerly called brightness) of a specimen is the lumi- nous flux emitted, reflected, or transmitted per unit solid angle and per unit projected area of the specimen. 3.1.8 Luminance ratio.-Luminance ratio is the ratio o
28、f the luminance of a portion of a test piece of diffusing ware to the lumi- nance of a corresponding portion of a stand- ard piece of diffusing ware of the same design 9999977 0004195 9 U Fed. Std. No. 3 made from white or nearly white material of the same type as the test piece, when each is illumi
29、nated by the same or an equivalent light source. 3.1.9 Luminous transmittance.-Luminous transmittance is the ratio of the light flux emitted from the test piece to that incident on the opposite surface. Luminous-transmit- tance requirements are applicable to light- transmitting ware bounded by plane
30、 parallel faces or by cylindrical or spherical faces con- centric with the light source. 3.1.10 Transmittance ratio. - Transmit- tance ratio is the ratio of the light flux transmitted by a test piece to the light flux transmitted by a standard piece of the same design made from colorless material of
31、 the same type as the test piece when each is similarly illuminated and viewed. The inten- sity of a signal light with a colorless lens may be multiplied by the transmittance ratio of a colored lens to obtain the intensity of the unit when the colored lens is employed. 3.1.11 Color temperature.-Colo
32、r tempera- ture of a light source is the temperature of a total (Planckian) radiator which has the same color as the source. Color temperature is usually expressed in degrees Kelvin (OK). The numerical value will depend on the value assigned to Cn in Plancks radiation equation for the total radiator
33、. Color temperatures of 2842“K., 2848“K., and 2854K. will have the same spectral distribution when computed with values of C, equal to 14,320; 14,350; and 14,380, respectively. In this standard, nominal values of color temperature are given to the nearest 10K. 3.2 Basic definitions of colors. 3.2.1
34、Basic principle of color definition by means of chromaticity coordinates.-For the usual conditions of observation, the color perceived to belong to a source of adequate intensity is determined by its chromaticity coordinates. It is therefore feasible to state chromaticity requirements for light sign
35、als 3 Licensed by Information Handling ServicesI FED-STD-3 7b 7777777 0004376 O W Fed. Std. No. 3 by bounding acceptable areas on the chro- maticity diagram, and the colors in this standard are so defined. Because the ICI coordinate system does not represent chro- maticity differences uniformly, it
36、is often convenient to transform the limits to the Rectangular Uniform-Chromaticity-Scale sys- tem (see 2.2.5 and 2.2.6). The corresponding limits for the two coordinate systems are shown in figures 1 and 3 (ICI) and figures 2 and 4 (RUCS). 3.2.2 Aviation colors. - Aviation colors shall conform to t
37、he fundamental colorimet- ric definitions specified in 3.2.2.1 to 3.2.2.7, inclusive. Note 2.-These definitions are identical with those adopted at the fourth session of the Aerodromes, Air Routes and Ground Aids (AGA) Division of the International Civil Aviation Organization (ICAO) in November 1949
38、, with the following exceptions : (I) The tolerances allowed for the pale limit for red and yellow are less than the ICAO tolerances ; (2) The limits for blue follow the ICAO (recommend practice” instead of the (stand- ard”; (3) The greenish and pinkish limits for white lie within the range permitte
39、d by ICAO. The colors aviation variable-yellow and aviation variable-white are intended only for lights employing incandescent-lamp sources with intensities controlled by vary- ing the lamp cussents and consequently the colors of the light signals. 3.2.2.1 Aviation red. y is not greater than 0.335 (
40、yellow limit) z is not greater than 0.003 (pale limit) 3.2.2.2 Aviation yellow. y is not less than 0.400 (red limit) x is not less than 0.560 (green limit) z is not greater than 0.010 (pale limit) 3.2.2.3 Aviation variable-yellow. y is not less than 0.385 (red limit) x is not less than 0.550 (green
41、limit) z is not greater than 0.010 (pale limit) (See 3.2.2.7 for additional requirements when used with aviation variable-white.) 3.2.2.4 Aviation green. x is not greater than 0.390 - 0.171 y (yellow limit) x is not greater than 0.100 + 0.410 y (pale limit) y is not less than 0.390 - 0.171 x (blue l
42、imit) 3.2.2.5 Aviation blue. x is not greater than 0.390 - 0.171 y (red limit) y is not greater than 0.400 - x (pale limit) y is not greater than 0.060 + 0.820 x (green limit) (pi divided by is not greater than 0.015. +,. is the total flux of the light under con- sideration, and +r is that part of t
43、his equipment would conform. But this source- filter combination would not permit a deci- sion to be made regarding equipment yield- ing chromaticities perceived as less satu- rated, because the inspector would have no basis for judging whether the chromaticity departure is great enough to cause the
44、 chromaticity point (x, y) of the equipment to fall outside the area on the chromaticity diagram permitted by 3.2.3.3. A source- filter combination for which x = 0.200, y = 0.497 would serve as a saturation and hue- limit standard (called pale and blue limit) for identification green. It would permi
45、t an inspector to judge conformity or noncon- formity of equipment yielding chromaticities both greener and slightly yellower than the standard, but if he perceived that the chro- maticity of the test piece was considerably yellower and of about the same saturation he would not know whether it met t
46、he re- quirement that y be not less than 0.257 + 1.200 x. Several working standards of chro- maticity are likely to be required by the inspector for each color. 5.3.1.2 Transmittance.-A standard filter of known luminous transmittance and of spectral characteristics similar to the test cover may be u
47、sed in conjunction with a visual or photoelectric photometer to test a cover for conformity to the requirements of 4.3. The inspector has essentially to set the visual photometer to equality of luminance, or to use the photoelectric photometer for an analogous purpose. 5.3.2 Selection. of working st
48、andards. - Working standard filters and color tempera- tures of sources to be employed for inspection should be specified in each procurement docu- ment. The chromaticity coordinates of the lamp-filter combination must lie within the . 7 Licensed by Information Handling ServicesFED-STD-3 76 7777777
49、0004200 7 TABLE 111.- Pyimarzj standard filters Fed. Std. No. 3 Buminant color smpera- x ture OK. 3ooo 0.665 2850 0.666 2360 0.669 1900 0.674 3000 0.666 2100 0.673 2850 0.696 2850 0.702 - T. 850 K.) Color Grades Limit Filter Z 0.000 O.OO0 O .o00 O .o00 O .o00 0.000 0.000 0:001 Y 0.335 0.334 0.331 0.326 0.334 0.327 0.304 0.297 Au All All All 36478 36478 36478 3647A 36568 36568 32188 31728 Aviation red- - - - Pale and yellov Pale and yellow Aviation yellom- (Filters not yet selected) I IL t yet sell ted) (Filters 7044A 7044A 73468 7346.A 73568 73568 73218 73218
