ASTM F1316-90(1996)

Standard Test Method for Measuring the Transmissivity of Transparent Parts

SCOPE
1.1 This test method describes an apparatus and procedure that is suitable for measuring the transmissivity of large, thick, or curved transparent parts including parts already installed. This test method is limited to transparencies that are relatively neutral with respect to wavelength (not highly colored).
1.2 Since the transmissivity (transmission coefficient) is a ratio of two luminance values, it has no units. The units of luminance recorded in the intermediate steps of this test method are not critical; any recognized units of luminance (for example, foot-lamberts or candelas per square metre) may be used, as long as use is consistent.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-Nov-1990
• Technical Committee: F07 - Aerospace and Aircraft
• Drafting Committee: F07.08 - Transparent Enclosures and Materials

Relations

• Replaced By: ASTM F1316-90(2002) - Standard Test Method for Measuring the Transmissivity of Transparent Parts
• Effective Date: 15-Nov-1990
• Referred By: ASTM F790-23 - Standard Guide for Testing Materials for Aerospace Plastic Transparent Enclosures
• Effective Date: 15-Nov-1990
• Referred By: ASTM F942-18(2023)e1 - Standard Guide for Selection of Test Methods for Interlayer Materials for Aerospace Transparent Enclosures
• Effective Date: 15-Nov-1990
• Referred By: ASTM F1863-16(2021) - Standard Test Method for Measuring the Night Vision Goggle-Weighted Transmissivity of Transparent Parts
• Effective Date: 15-Nov-1990

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 1316 – 90 (Reapproved 1996)
Standard Test Method for
Measuring the Transmissivity of Transparent Parts
This standard is issued under the fixed designation F 1316; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Test Method D 1003 has received wide acceptance as a test method to measure luminous
transmissivity in transparent materials. However, because Test Method D 1003 requires critical
alignment of equipment on both sides of the transparency, it is not suited to measuring the
transmissivity of large, curved parts or parts that are installed. In addition, Test Method D 1003
measures the luminous transmissivity of the material in a direction perpendicular to the surface of the
material. For the majority of aircraft windscreens, the pilot is not viewing through the transparency
perpendicular to the surface. Since the transmissivity varies as a function of viewing angle the values
of transmissivity measured perpendicular to the surface do not indicate what the pilot will see when
viewing through the windscreen.
For the above reasons this test method has been developed to allow the measurement of
transmissivity of a transparent part at any angle. Since the relative alignment of the equipment items
on either side of the transparency is not critical, this test method can also be used on large, thick, or
curved parts and parts that are already installed.
1. Scope 3. Terminology
1.1 This test method describes an apparatus and procedure 3.1 Definitions:
that is suitable for measuring the transmissivity of large, thick, 3.1.1 black reference—a light-absorbing, black material,
or curved transparent parts including parts already installed. such as black velvet flocking.
This test method is limited to transparencies that are relatively 3.1.2 photometer—a device that measures luminance as
neutral with respect to wavelength (not highly colored). defined by the spectral sensitivity of the photopic curve.
1.2 Since the transmissivity (transmission coefficient) is a 3.1.3 Photopic curve—the photopic curve is the spectral
ratio of two luminance values, it has no units. The units of sensitivity of the eye for daytime conditions as Committee
luminance recorded in the intermediate steps of this test Internationale d’Elairage (CIE) 1931 standard observer.
method are not critical; any recognized units of luminance (for 3.1.4 regulated light source—a light source with electronic
example, foot-lamberts or candelas per square metre) may be feedback to ensure that its illuminance remains constant over
used, as long as use is consistent. time.
1.3 This standard does not purport to address all of the 3.1.5 transmission coeffıcient—same as transmissivity.
safety concerns, if any, associated with its use. It is the 3.1.6 transmissivity—the transmissivity of a transparent
responsibility of the user of this standard to establish appro- medium is the ratio of the luminance of an object measured
priate safety and health practices and determine the applica- through the medium to the luminance of the object measured
bility of regulatory limitations prior to use. directly.
2. Referenced Documents 4. Summary of Test Method
2.1 ASTM Standards: 4.1 A regulated light source with a relatively large, diffusely
D 1003 Test Method for Haze and Luminous Transmittance radiating surface area is placed on one side of a transparent part
of Transparent Plastics to be measured. A black, light-absorbing reference surface is
placed next to the light source. A photometer is used to
measure the luminance of the light source and black reference
directly and through the transparency. The light source reading
This test method is under the jurisdiction of ASTM Committee F-7 on
Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 on
measured through the transparency minus the black reference
Transparent Enclosures and Materials.
reading through the transparency is divided by the light source
Current edition approved Nov. 15, 1990. Published March 1991.
2 measured directly minus the black reference measured directly
Annual Book of ASTM Standards, Vol 08.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 1316
(see Eq 1). This ratio is the transmission coefficient of the of two quantities measured by the photometer it is not
transparency. The black reference surface is used to correct the necessary that the photometer be calibrated in absolute lumi-
measurement from the effects of light scatter due to haze and nance units.
from reflections.
9. Procedure
5. Significance and Use 9.1 Place the light source (or white reflective surface) on
one side of the transparency such that is can be viewed from
5.1 Significance—This test method provides a means to
the other side of the transparency. The transparency should be
measure the transmissivity of parts in the field (already
at the desired angle for measurement. The distance from the
installed on aircraft) and of large, thick or curved parts that
light source to the transparency is not critical but must be
may not lend themselves to measurement using Test Method
greater than 30 cm (11.8 in.) to prevent erroneous readings due
D 1003.
to light scatter and reflections. The distance from the light
5.2 Use—This test method may be used on any transparent
source to the photometer is also not critical but should be short
part. It is primarily intended for use on large, curved, or thick
enough so that the photometer measurement field easily falls
parts that may already be installed (for example, windscreens
within the emitting area of the light source. The distance from
on aircraft).
the transparency to the photometer is not critical and may be as
6. Apparatus
small as 0 cm. The black reference should be placed adjacent
to the light source so that it may also be viewed through the
6.1 Test Environment—It is preferable to carry out this test
transparency. The light absorbing cloth should be placed next
method in a light controlled environment although this is not
to the transparency on the opposite side from the light source
absolutely necessary. The transparency should be shaded from
(see Fig. 1).
direct sunlight falling on the surface and a light absorbing
9.2 If the transparency is subject to direct sunlight, a solar
black cloth should be placed in the appropriate reflection
shield should be used to shade the area of the transparency (see
geometry with respect to the transparency to reduce reflections.
Fig. 1).
6.2 Photometer—Any properly calibrated photometer may
9.3 The photometer is then used to measure the luminance
be used for this measurement. It should have a measurement
of the light source and the black reference. These readings are
field that is smaller than the regulated light source to ensure
designated L and L respectively. The light source and black
accurate readings. It is recommended that a small, portable s b
reference are then measured again but this time viewing
photometer with a 1° measurement field (or less) be used.
through the transparency. These readings are L and L
6.3 Light Source—The light source should be regulated to s b
t t
respectively. Both the direct measurements and the measure-
ensure that it does not change luminance during the reading
ments through the transparency should be made at about the
period. It should have a relatively large, diffusely emitting
same distance and angle from the light source.
surface area to permit easy measurement when using the
photometer. The spectral distribution of the light source is not
10. Calculation
critical unless the transparency under test has significant
10.1 The transmissivity of the transparency is calculated
spectral peaks or voids. For daylight measurements it is
possible to use a white reflecting surface illuminated by
sunlight instead of a powered light source. Care must be taken
that the luminance of the reflective surface does not change
during the reading.
6.4 Black Reference—A shaded, light-absorbing black ma-
terial such as velvet may be used to increase the accuracy of the
measurement. This reference must have about the same area as
the light source or reflective material used for the light reading
since the photometer must also measure the apparent lumi-
nance of the black reference.
7. Test Specimen
7.1 Clean the part to be measured, using any acceptable
procedure, to remove any surface contaminants that may
contribute to the loss of transmissivity. No special conditioning
other than cleaning is required.
8. Calibration and Standardization
8.1 The photometer should have the same spectral sensitiv-
ity as the eye but since the measurement involves the division
Turk, H. L. and Merkel, H. S., A New Method for Measuring the Transmissivity
of Aircraft Transparencies. Technical Report AAMRL-TR-89-044, Armstrong
Aer
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