ASTM F733-09(2014)
(Practice)Standard Practice for Optical Distortion and Deviation of Transparent Parts Using the Double-Exposure Method
Standard Practice for Optical Distortion and Deviation of Transparent Parts Using the Double-Exposure Method
SIGNIFICANCE AND USE
5.1 Transparent parts, such as aircraft windshields and windows, can be inspected using this practice, and the amount of optical distortion or deviation can be measured. The measurement can be checked for acceptability against the specification for the part. The photograph (digital file, print or negative) can be maintained as a permanent record of the optical quality of the part.
SCOPE
1.1 This photographic practice determines the optical distortion and deviation of a line of sight through a simple transparent part, such as a commercial aircraft windshield or a cabin window. This practice applies to essentially flat or nearly flat parts and may not be suitable for highly curved materials.
1.2 Test Method F801 addresses optical deviation (angluar deviation) and Test Method F2156 addresses optical distortion using grid line slope. These test methods should be used instead of Practice F733 whenever practical.
1.3 This standard does not purport to address the safety concerns 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: F733 − 09 (Reapproved 2014)
Standard Practice for
Optical Distortion and Deviation of Transparent Parts Using
the Double-Exposure Method
ThisstandardisissuedunderthefixeddesignationF733;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.4 May also be expressed as the slope of the angle of
localized grid line bending, for example, 1 in 5 (see Fig. 1).
1.1 This photographic practice determines the optical dis-
3.1.5 installed angle—the part attitude as installed in the
tortion and deviation of a line of sight through a simple
aircraft.Definedbytheanglebetweenahorizontallineandthe
transparent part, such as a commercial aircraft windshield or a
planeofthepart,andtheangleofsweepbackfromahorizontal
cabinwindow.Thispracticeappliestoessentiallyflatornearly
line normal to the center line of the aircraft. See Fig. 2 for an
flat parts and may not be suitable for highly curved materials.
example.
1.2 Test Method F801 addresses optical deviation (angluar
deviation) and Test Method F2156 addresses optical distortion
4. Summary of Practice
using grid line slope. These test methods should be used
4.1 The transparent part is placed a given distance from a
instead of Practice F733 whenever practical.
grid line pattern. A camera is placed so as to photograph the
1.3 This standard does not purport to address the safety
gridpatternasviewedthroughthepart.Thephotographisthen
concerns associated with its use. It is the responsibility of the
examined and optical distortion or deviation is measured.
user of this standard to establish appropriate safety and health
practices and determine the applicability of regulatory limita-
5. Significance and Use
tions prior to use.
5.1 Transparent parts, such as aircraft windshields and
2. Referenced Documents
windows, can be inspected using this practice, and the amount
of optical distortion or deviation can be measured. The
2.1 ASTM Standards:
measurement can be checked for acceptability against the
F801Test Method for Measuring OpticalAngular Deviation
specification for the part. The photograph (digital file, print or
of Transparent Parts
negative) can be maintained as a permanent record of the
F2156Test Method for Measuring Optical Distortion in
optical quality of the part.
Transparent Parts Using Grid Line Slope
6. Apparatus
3. Terminology
6.1 Test Room—The test room must be large enough to
3.1 Definitions:
properly locate the required testing equipment.
3.1.1 deviation—the displacement of a line or object when
6.1.1 MethodArequires a room approximately 12 m (40 ft)
viewed through the transparent part. Expressed as the angular
measurementofthedisplacedline,forexample,milliradiansof long.
angle. 6.1.2 Method B requires a room approximately 7 m (23 ft)
long.
3.1.2 distortion—the rate of change of deviation resulting
6.1.3 The walls, ceiling, and floor shall have low reflec-
from an irregularity in a transparent part.
tance. A flat black paint or coating is preferred.
3.1.3 Expressed as the angular bending of the light ray per
6.2 Grid Board—The grid board provides a defined pattern
unit of length of the part, for example, milliradians per
againstwhichthetransparentpartisexamined.Gridboardsare
centimetre.
of the following types.
6.2.1 Type 1—The grid board is composed of white strings
held taut, each spaced at a specific interval, with the strings
This practice is under the jurisdiction ofASTM Committee F07 on Aerospace
andAircraft and is the direct responsibility of Subcommittee F07.08 on Transparent
stretched vertically and horizontally.The grid board frame and
Enclosures and Materials.
background shall have a flat black finish to reduce light
Current edition approved Dec. 1, 2014. Published December 2014. Originally
reflection. A bank of fluorescent lights at each side provides
approved in 1981. Last previous edition approved in 2009 as F733–09. DOI:
10.1520/F0733-09R14. illumination of the strings.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F733 − 09 (2014)
FIG. 1 Optical Distortion Represented by Tangent
6.2.2 Type 2—The grid board is a transparent sheet having 6.3 Camera—Unless otherwise specified, the camera shall
anopaque,flatblackoutersurfaceexceptforthegridlines.The utilizea4by 5-in. film size.The lens opening used shall be f8
grid lines are left transparent, and when lighted from behind or smaller. The camera shall be firmly mounted to prevent any
with fluorescent lights, provide a bright grid pattern with movement during the photographic exposure. Digital cameras
excellent photographic characteristics. are acceptable if they have sufficient resolution (pixel count)
for the size of part to be measured.
TABLE 1 Optical Inspection Distances
7. Test Specimen
Method A
Camera-to-grid-board distance 1000 cm (32 ft 10 in.)
7.1 The part to be checked shall be cleaned, using any
Camera-to-part distance 550 cm (18 ft 1 in.)
acceptable procedure, to remove any foreign material that
Part-to-grid board distance 450 cm (14 ft 9 in.)
Method B might cause localized optical distortion. No special
Camera-to-grid-board distance 450 cm (14 ft 9 in.)
conditioning, other than cleaning, is required.The part shall be
Camera-to-part distance 150 cm (4 ft 11 in.)
at ambient temperature.
Part-to-grid-board distance 300 cm (9 ft 10 in.)
8. Procedure
6.2.3 Type 3—The grid board is a rigid sheet of material 8.1 The procuring activity shall specify whether Method A
which has a grid pattern printed on the front surface. Details of or Method B (see Table 1) or some other set of distances shall
the grid lines, pattern, and lighting shall be as specified by the be used to measure optical distortion and deviation. If Method
procuring activity. Aor Method B are not used, the actual distances used shall be
6.2.4 The grid board shall have a width and height large reported. When the part is flat and mounted nearly vertical,
enough so that the area of the part to be photographed can be MethodAisamorestringenttestthanMethodB.Certainparts
superimposedwithintheperimeterofthegridboard.Detailsof may show substantial optical deviation by Method B simply
the grid square size shall be as specified by the procuring duetorefractionofthelightrays.Ifthepartisawindscreenthe
activity, but grids shall not have a line spacing less than 1.27 procuring activity may require the camera to be positioned at
cm ( ⁄2 in.), or more than 2.54 cm (1 in.). the pilot’s eye position.
F733 − 09 (2014)
NOTE 1—The camera viewing position line of sight shall be through the center of the pilot’s eye position for the part as specified by the procuring
activity.
FIG. 2 Example of Installed Angle
8.2 Measure optical distortion through the
...
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: F733 − 09 F733 − 09 (Reapproved 2014)
Standard Practice for
Optical Distortion and Deviation of Transparent Parts Using
the Double-Exposure Method
This standard is issued under the fixed designation F733; 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 photographic practice determines the optical distortion and deviation of a line of sight through a simple transparent
part, such as a commercial aircraft windshield or a cabin window. This practice applies to essentially flat or nearly flat parts and
may not be suitable for highly curved materials.
1.2 Test Method F801 addresses optical deviation (angluar deviation) and Test Method F2156 addresses optical distortion using
grid line slope. These test methods should be used instead of Practice F733 whenever practical.
1.3 This standard does not purport to address the safety concerns 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
2.1 ASTM Standards:
F801 Test Method for Measuring Optical Angular Deviation of Transparent Parts
F2156 Test Method for Measuring Optical Distortion in Transparent Parts Using Grid Line Slope
3. Terminology
3.1 Definitions:
3.1.1 deviation—the displacement of a line or object when viewed through the transparent part. Expressed as the angular
measurement of the displaced line, for example, milliradians of angle.
3.1.2 distortion—the rate of change of deviation resulting from an irregularity in a transparent part.
3.1.3 Expressed as the angular bending of the light ray per unit of length of the part, for example, milliradians per centimetre.
3.1.4 May also be expressed as the slope of the angle of localized grid line bending, for example, 1 in 5 (see Fig. 1).
3.1.5 installed angle—the part attitude as installed in the aircraft. Defined by the angle between a horizontal line and the plane
of the part, and the angle of sweep back from a horizontal line normal to the center line of the aircraft. See Fig. 2 for an example.
4. Summary of Practice
4.1 The transparent part is placed a given distance from a grid line pattern. A camera is placed so as to photograph the grid
pattern as viewed through the part. The photograph is then examined and optical distortion or deviation is measured.
5. Significance and Use
5.1 Transparent parts, such as aircraft windshields and windows, can be inspected using this practice, and the amount of optical
distortion or deviation can be measured. The measurement can be checked for acceptability against the specification for the part.
The photograph (digital file, print or negative) can be maintained as a permanent record of the optical quality of the part.
6. Apparatus
6.1 Test Room—The test room must be large enough to properly locate the required testing equipment.
6.1.1 Method A requires a room approximately 12 m (40 ft) long.
This practice 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 May 15, 2009Dec. 1, 2014. Published June 2009December 2014. Originally approved in 1981. Last previous edition approved in 20032009 as
F733 – 90 (2003).F733 – 09. DOI: 10.1520/F0733-09.10.1520/F0733-09R14.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F733 − 09 (2014)
FIG. 1 Optical Distortion Represented by Tangent
6.1.2 Method B requires a room approximately 7 m (23 ft) long.
6.1.3 The walls, ceiling, and floor shall have low reflectance. A flat black paint or coating is preferred.
6.2 Grid Board—The grid board provides a defined pattern against which the transparent part is examined. Grid boards are of
the following types.
6.2.1 Type 1—The grid board is composed of white strings held taut, each spaced at a specific interval, with the strings stretched
vertically and horizontally. The grid board frame and background shall have a flat black finish to reduce light reflection. A bank
of fluorescent lights at each side provides illumination of the strings.
6.2.2 Type 2—The grid board is a transparent sheet having an opaque, flat black outer surface except for the grid lines. The grid
lines are left transparent, and when lighted from behind with fluorescent lights, provide a bright grid pattern with excellent
photographic characteristics.
TABLE 1 Optical Inspection Distances
Method A
Camera-to-grid-board distance 1000 cm (32 ft 10 in.)
Camera-to-part distance 550 cm (18 ft 1 in.)
Part-to-grid board distance 450 cm (14 ft 9 in.)
Method B
Camera-to-grid-board distance 450 cm (14 ft 9 in.)
Camera-to-part distance 150 cm (4 ft 11 in.)
Part-to-grid-board distance 300 cm (9 ft 10 in.)
6.2.3 Type 3—The grid board is a rigid sheet of material which has a grid pattern printed on the front surface. Details of the
grid lines, pattern, and lighting shall be as specified by the procuring activity.
6.2.4 The grid board shall have a width and height large enough so that the area of the part to be photographed can be
superimposed within the perimeter of the grid board. Details of the grid square size shall be as specified by the procuring activity,
but grids shall not have a line spacing less than 1.27 cm ( ⁄2 in.), or more than 2.54 cm (1 in.).
F733 − 09 (2014)
NOTE 1—The camera viewing position line of sight shall be through the center of the pilot’s eye position for the part as specified by the procuring
activity.
FIG. 2 Example of Installed Angle
6.3 Camera—Unless otherwise specified, the camera shall utilize a 4 by 5-in. film size. The lens opening used shall be f 8 or
smaller. The camera shall be firmly mounted to prevent any movement during the photographic exposure. Digital cameras are
acceptable if they have sufficient resolution (pixel count) for the size of part to be measured.
7. Test Specimen
7.1 The part to be checked shall be cleaned, using any acceptable procedure, to remove any foreign material that might cause
localized optical distortion. No special conditioning, other than cleaning, is required. The part shall be at ambient temperature.
8. Procedure
8.1 The procuring activity shall specify whether Method A or Method B (see Table 1) or some other set of distances shall be
used to measure optical distortion and deviation. If Method A or Method B are not used, the actual distances used shall be reported.
When the part is flat and mounted nearly vertical, Method A is a more stringent test than Method B. Certain parts may show
substantial optical deviation by Method
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