ASTM F2469-10
(Test Method)Standard Test Method for Measuring Optical Angular Deviation of Transparent Parts Using the Double-Exposure Method
Standard Test Method for Measuring Optical Angular Deviation of Transparent Parts Using the Double-Exposure Method
SIGNIFICANCE AND USE
The optical angular deviation of flat transparent parts, such as aircraft windshields, canopies, cabin windows, and visors, can be measured using these methods. Angular deviation in a windscreen or visor can cause objects to appear at a location different from where they actually are. Variations in angular deviation can be used to characterize distortion and magnification in transparent parts. Also, angular deviation measurements made from the typical right and left eye positions for a windscreen or other transparent medium can be used to determine binocular disparity differences (see Test Method F1181).
SCOPE
1.1 This test method covers the measurement of the optical angular deviation of a light ray imposed by flat transparent parts such as a commercial or military aircraft windshield, canopy or cabin window.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.2.1 Exceptions—The values given in parentheses are for information only. Also, print size is provided in inch-pound measurements.
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.
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Designation: F2469 − 10
StandardTest Method for
Measuring Optical Angular Deviation of Transparent Parts
1
Using the Double-Exposure Method
This standard is issued under the fixed designation F2469; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope ans) and is a function of the angle of incidence at each surface
of the material and the index of refraction of the material.
1.1 This test method covers the measurement of the optical
3.1.2 grid board—an optical evaluation tool used to detect
angular deviation of a light ray imposed by flat transparent
the presence of distortion in transparent parts. It is usually, but
parts such as a commercial or military aircraft windshield,
not always, a vertical rectangular backboard with horizontal
canopy or cabin window.
and vertical intersecting lines with maximum contrast between
1.2 The values stated in SI units are to be regarded as
the white lines and the black background.
standard. No other units of measurement are included in this
standard.
4. Summary of Test Method
1.2.1 Exceptions—The values given in parentheses are for
4.1 The flat transparent part is mounted at a specified
information only. Also, print size is provided in inch-pound
distance from a grid board test pattern with its surface parallel
measurements.
with the plane of the grid board test pattern.Acamera is placed
1.3 This standard does not purport to address all of the
so as to record a double exposure photograph of the grid
safety concerns, if any, associated with its use. It is the
pattern as viewed through the transparency from a specified
responsibility of the user of this standard to establish appro-
viewing distance from the grid board test pattern. The image is
priate safety and health practices and determine the applica-
then measured to assess the level of optical deviation present.
bility of regulatory limitations prior to use.
This method basically measures the amount of angular devia-
tion present in a flat transparent part when viewing through it
2. Referenced Documents
perpendicular to its surface. The part to be measured must be
2
2.1 ASTM Standards:
essentially flat and mounted such that its surface is perpendicu-
F801 Test Method for Measuring OpticalAngular Deviation
lar to the camera axis. This is an alternate method to Test
of Transparent Parts
Method F801 and is essentially the same as the portion of
F1181 Test Method for Measuring Binocular Disparity in
Practice F733 that deals with optical deviation.
Transparent Parts
F733 Practice for Optical Distortion and Deviation of Trans-
5. Significance and Use
parent Parts Using the Double-Exposure Method
5.1 The optical angular deviation of flat transparent parts,
such as aircraft windshields, canopies, cabin windows, and
3. Terminology
visors, can be measured using these methods. Angular devia-
3.1 Definitions:
tion in a windscreen or visor can cause objects to appear at a
3.1.1 angular deviation—the angular displacement of a light
location different from where they actually are. Variations in
rayfromitsoriginalpathcausedbynon-parallelismofopposite
angular deviation can be used to characterize distortion and
surfaces as it passes through a transparent material, which is
magnification in transparent parts. Also, angular deviation
expressed in units of angle (degree, minutes of arc, milliradi-
measurements made from the typical right and left eye posi-
tions for a windscreen or other transparent medium can be used
1 to determine binocular disparity differences (see Test Method
This test method is under the jurisdiction of ASTM Committee F07 on
Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 on
F1181).
Transparent Enclosures and Materials.
Current edition approved May 1, 2010. Published June 2010. Originally
6. Apparatus
approved in 2005. Last previous edition approved in 2005 as F2469 – 05. DOI:
10.1520/F2469-10.
6.1 Test Room—The test room must be large enough to
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
properly locate the required testing equipment.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1.1 The walls, ceiling, and floor shall have low reflec-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tance. A flat black paint or coating is preferred.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F2469 − 10
6.2 Grid Board—The grid board provides a defined pattern agen
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F2469–05 Designation:F2469–10
Standard Test Method for
Measuring Optical Angular Deviation of Transparent Parts
1
Using the Double-Exposure Method
This standard is issued under the fixed designation F2469; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the measurement of the optical angular deviation of a light ray imposed by flat transparent parts
such as a commercial or military aircraft windshield, canopy or cabin window.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.2.1 Exceptions—The values given in parentheses are for information only. Also, print size is provided in inch-pound
measurements.
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.
2. Referenced Documents
2
2.1 ASTM Standards:
F801 Test Method for Measuring Optical Angular Deviation of Transparent Parts
F1181 Test Method for Measuring Binocular Disparity in Transparent Parts Test Method for Measuring Binocular Disparity in
Transparent Parts
F733 Practice for Optical Distortion and Deviation of Transparent Parts Using the Double-Exposure Method
3. Terminology
3.1 Definitions:
3.1.1 angular deviation—the angular displacement of a light ray from its original path caused by non-parallelism of opposite
surfaces as it passes through a transparent material, which is expressed in units of angle (degree, minutes of arc, milliradians) and
is a function of the angle of incidence at each surface of the material and the index of refraction of the material.
3.1.2 design eye—the reference point in aircraft design from which all visual or optical anthropometrical design considerations
are taken.
3.1.3grid board—an optical evaluation tool used to detect the presence of distortion in transparent parts. It is usually, but not
always, a vertical rectangular backboard with horizontal and vertical intersecting lines with maximum contrast between the white
lines and the black background.
3.1.4installed angle—the transparency (windscreen, canopy, or cabin window) orientation as installed in the aircraft, defined by
the angle between a horizontal line (line-of-sight) and a plane tangent to the surface of the transparency (see Fig. 1).
4. Summary of Test Method
4.1 The flat transparent part is mounted, preferably mounted at the installed angle, a specified distance from a grid board test
pattern with its surface parallel with the plane of the grid board test pattern.Acamera is placed so as to record a double exposure
photograph of the grid pattern as viewed through the transparency from the design eye or other a specified viewing position
specified by distance from the procuring agency. grid board test pattern. The image is then measured to assess the level of optical
deviation present. This method basically measures the amount of angular deviation present in a flat transparent part compared to
a reference part (if required), which is referred when viewing through it perpendicular to as a compensator plate. If the its surface.
The part to be measured is must be essentially flat and mounted such that its surface is perpendicular to the camera axis then no
1
This test method is under the jurisdiction of ASTM Committee F07 on Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 on Transparent
Enclosures and Materials.
Current edition approved Mar. 1, 2005. Published March 2005. DOI: 10.1520/F2469-05.
Current edition approved May 1, 2010. Published June 2010. Originally approved in 2005. Last previous edition approved in 2005 as F2469 – 05. DOI: 10.1520/F2469-10.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
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F2469–10
FIG. 2 Suggested Distances
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