ASTM F1181-09(2014)
(Test Method)Standard Test Method for Measuring Binocular Disparity in Transparent Parts
Standard Test Method for Measuring Binocular Disparity in Transparent Parts
SIGNIFICANCE AND USE
5.1 Diplopia or doubling of vision occurs when there is sufficient binocular disparity present so that the bounds of Panum's area (the area of single vision) is exceeded. This condition arises whenever one object is significantly closer (or farther) than another so that looking at one will cause the image of the other to appear double. This can be easily demonstrated: Close one eye and look at a clock (or other object) on a distant wall. Now place your thumb to one side of the image of the clock. Now open both eyes. If you look at the clock, you should see two thumbs. If you look at your thumb, you should see two clocks.
5.2 Complaints from pilots flying aircraft equipped with wide field of view head up displays (HUDs) such as the LANTIRN HUD indicated that they were experiencing discomfort (eye fatigue, headaches, and so forth.) or seeing either two targets or two pippers (aiming symbols on the HUD) when using the HUD. Subsequent investigations revealed that the problem arose from the fact that the aircraft transparency and the HUD significantly changed the optical distances of the target and the HUD imagery so that binocular disparity, which exceeded Panum's area was induced. Use of this test method provides a procedure by which the amount of binocular disparity being experienced by a human operator due to the presence of a transparent part in his field of view may be easily and precisely measured.
SCOPE
1.1 This test method covers the amount of binocular disparity that is induced by transparent parts such as aircraft windscreens, canopies, HUD combining glasses, visors, or goggles. This test method may be applied to parts of any size, shape, or thickness, individually or in combination, so as to determine the contribution of each transparent part to the overall binocular disparity present in the total “viewing system” being used by a human operator.
1.2 This test method represents one of several techniques that are available for measuring binocular disparity, but is the only technique that yields a quantitative figure of merit that can be related to operator visual performance.
1.3 This test method employs apparatus currently being used in the measurement of optical angular deviation under Method F801.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 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: F1181 − 09 (Reapproved 2014)
Standard Test Method for
Measuring Binocular Disparity in Transparent Parts
This standard is issued under the fixed designation F1181; 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 3.1.1 angulardeviation—theangulardisplacementofalight
ray as it passes through a transparent part, expressed as an
1.1 This test method covers the amount of binocular dispar-
angular measurement, for example, degree, minutes of arc,
ity that is induced by transparent parts such as aircraft
milliradians. Since it is an angular measurement, the amount of
windscreens, canopies, HUD combining glasses, visors, or
linear displacement increases with distance.
goggles. This test method may be applied to parts of any size,
3.1.2 binocular disparity—the difference between the two
shape, or thickness, individually or in combination, so as to
images on the retina resulting from the lateral separation
determine the contribution of each transparent part to the
between the two eyes when viewing an object at a fixation
overall binocular disparity present in the total “viewing sys-
point or due to the fact that an object is either nearer or farther
tem” being used by a human operator.
than the fixation point. A certain amount of disparity is
1.2 This test method represents one of several techniques
beneficial and natural, leading to the perception of depth.
that are available for measuring binocular disparity, but is the
However, when the disparity exceeds the limits for binocular
onlytechniquethatyieldsaquantitativefigureofmeritthatcan
fusion, doubling of vision, eye fatigue, and headaches occur as
be related to operator visual performance.
the eyes strain to merge the disparate images.
1.3 This test method employs apparatus currently being
3.1.3 diplopia—the doubling of images of an object due to
used in the measurement of optical angular deviation under
the fact that the object is either nearer or farther than the point
Method F801.
of fixation or due to the fact that the lines of regard of the eyes
1.4 The values stated in inch-pound units are to be regarded
do not intersect at the point of fixation.
as standard. The values given in parentheses are mathematical
3.1.4 Panum’s area—the area on the retina in which the
conversions to SI units that are provided for information only
eyes are able to fuse disparate images so that single vision
and are not considered standard.
occurs.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
4.1 Using an optoelectronic system (consisting of a trans-
priate safety and health practices and determine the applica-
mitter and a receiver, described in Test Method F801) and with
bility of regulatory limitations prior to use.
the part held in its installed angle, two sets of angular deviation
measurements are made at several intervals (for example, 2°)
2. Referenced Documents
in both azimuth and elevation. The extent of the area to be
2.1 ASTM Standards:
measured is dependent on the type of part being measured, for
F801 Test Method for Measuring OpticalAngular Deviation
example, windscreen, visor, and so forth. The first set of
of Transparent Parts
measures is taken from the left eye position, the second from
the right eye position. The separation between the two eye
3. Terminology
positions is 2.5 in. (6.35 cm), a distance equivalent to the
3.1 Definitions:
interpupillary distance between the human eyes. The measure-
ments taken from the left eye position are subtracted from that
1 taken from the right eye position to determine binocular
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 disparity.
Transparent Enclosures and Materials.
Current edition approved Dec. 1, 2014. Published December 2014. Originally
5. Significance of Use
approved in 1988. Last previous edition approved in 2009 as F1181 – 09. DOI:
10.1520/F1181-09R14.
5.1 Diplopia or doubling of vision occurs when there is
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
sufficient binocular disparity present so that the bounds of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Panum’s area (the area of single vision) is exceeded. This
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. condition arises whenever one object is significantly closer (or
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1181 − 09 (2014)
farther)thananothersothatlookingatonewillcausetheimage 8. Procedure
of the other to appear double. This can be easily demonstrated:
8.1 Mount the transparent part on a fixture that allows
Close one eye and look at a clock (or other object) on a distant
accurate determination of the elevation and azimuth position of
wall. Now place your thumb to one side of the image of the
the part.
clock. Now open both eyes. If you look at the clock, you
8.2 Locate and firmly mount the transmitter at a position
should see two thumbs. If you look at your thumb, you should
corresponding to the design eye position (the cyclopean eye
see two clocks.
position). To obtain the position corresponding to the left
5.2 Complaints from pilots flying aircraft equipped with
(right) eye position, move the transparency 1.25 in. (31.7 mm)
wide field of view head up displays (HUDs) such as the
to the right (left) of the design eye position.
LANTIRN HUD indicated that they were experiencing dis-
8.3 Locate and firmly mount the receiver external to the part
comfort (eye fatigue, headaches, and so forth.) or seeing either
to be measured and at a distance from the transmitter that is
two targets or two pippers (aiming symbols on the HUD) when
commensurate with the part being measured (sufficient to
using the HUD. Subsequent investigations revealed that the
ensure the part being measured will not physically contact the
problem arose from the fact that the aircraft transparency and
receiver unit).
the HUD significantly changed the optical distances of the
target and the HUD imagery so that binocular disparity, which 8.4 Establish a baseline or zero determination without a
transparency in the optical path. Record the number as dis-
exceeded Panum’s area was induced. Use of this test method
provides a procedure by which the amount of binocular played on the digital readout under this condition.
disparity being experienced by a human operator due to the
8.5 Locatethetransparencypartbetweenthetransmitterand
presence of a transparent part in his field of view may be easily
receiver. Take the readings from the left (right) eye position
and precisely measured.
over area of interest as specified by using activity. Record
readingsforeachpoint(azimuth,elevation)ofthetransparency
6. Apparatus
thatismeasured.De
...
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: F1181 − 09 F1181 − 09 (Reapproved 2014)
Standard Test Method for
Measuring Binocular Disparity in Transparent Parts
This standard is issued under the fixed designation F1181; 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 amount of binocular disparity that is induced by transparent parts such as aircraft windscreens,
canopies, HUD combining glasses, visors, or goggles. This test method may be applied to parts of any size, shape, or thickness,
individually or in combination, so as to determine the contribution of each transparent part to the overall binocular disparity present
in the total “viewing system” being used by a human operator.
1.2 This test method represents one of several techniques that are available for measuring binocular disparity, but is the only
technique that yields a quantitative figure of merit that can be related to operator visual performance.
1.3 This test method employs apparatus currently being used in the measurement of optical angular deviation under Method
F801.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.5 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
2.1 ASTM Standards:
F801 Test Method for Measuring Optical Angular Deviation of Transparent Parts
3. Terminology
3.1 Definitions:
3.1.1 angular deviation—the angular displacement of a light ray as it passes through a transparent part, expressed as an angular
measurement, for example, degree, minutes of arc, milliradians. Since it is an angular measurement, the amount of linear
displacement increases with distance.
3.1.2 binocular disparity—the difference between the two images on the retina resulting from the lateral separation between the
two eyes when viewing an object at a fixation point or due to the fact that an object is either nearer or farther than the fixation
point. A certain amount of disparity is beneficial and natural, leading to the perception of depth. However, when the disparity
exceeds the limits for binocular fusion, doubling of vision, eye fatigue, and headaches occur as the eyes strain to merge the
disparate images.
3.1.3 diplopia—the doubling of images of an object due to the fact that the object is either nearer or farther than the point of
fixation or due to the fact that the lines of regard of the eyes do not intersect at the point of fixation.
3.1.4 Panum’s area—the area on the retina in which the eyes are able to fuse disparate images so that single vision occurs.
4. Summary of Test Method
4.1 Using an optoelectronic system (consisting of a transmitter and a receiver, described in Test Method F801) and with the part
held in its installed angle, two sets of angular deviation measurements are made at several intervals (for example, 2°) in both
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 May 15, 2009Dec. 1, 2014. Published June 2009December 2014. Originally approved in 1988. Last previous edition approved in 20032009 as
F1181 – 96 (2003).F1181 – 09. DOI: 10.1520/F1181-09.10.1520/F1181-09R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM 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
F1181 − 09 (2014)
azimuth and elevation. The extent of the area to be measured is dependent on the type of part being measured, for example,
windscreen, visor, and so forth. The first set of measures is taken from the left eye position, the second from the right eye position.
The separation between the two eye positions is 2.5 in. (6.35 cm), a distance equivalent to the interpupillary distance between the
human eyes. The measurements taken from the left eye position are subtracted from that taken from the right eye position to
determine binocular disparity.
5. Significance of Use
5.1 Diplopia or doubling of vision occurs when there is sufficient binocular disparity present so that the bounds of Panum’s area
(the area of single vision) is exceeded. This condition arises whenever one object is significantly closer (or farther) than another
so that looking at one will cause the image of the other to appear double. This can be easily demonstrated: Close one eye and look
at a clock (or other object) on a distant wall. Now place your thumb to one side of the image of the clock. Now open both eyes.
If you look at the clock, you should see two thumbs. If you look at your thumb, you should see two clocks.
5.2 Complaints from pilots flying aircraft equipped with wide field of view head up displays (HUDs) such as the LANTIRN
HUD indicated that they were experiencing discomfort (eye fatigue, headaches, and so forth.) or seeing either two targets or two
pippers (aiming symbols on the HUD) when using the HUD. Subsequent investigations revealed that the problem arose from the
fact that the aircraft transparency and the HUD significantly changed the optical distances of the target and the HUD imagery so
that binocular disparity, which exceeded Panum’s area was induced. Use of this test method provides a procedure by which the
amount of binocular disparity being experienced by a human operator due to the presence of a transparent part in his field of view
may be easily and precisely measured.
6. Apparatus
6.1 Transmitter capable of projecting collimated light rays from a suitable target. The transmitter should be firmly fixed to the
floor or other stationary fixture.
6.2 Receiver firmly affixed to the floor or a stable platform consisting of the following components:
6.2.1 Displacement Compensation and Imaging Lens with a focal length of 10 in. (254 mm).
6.2.2 Optical Beam Splitter to separate the incoming light into two orthogonal elements (elevation and azimuth). The beam
splitter should be positioned to keep both optical path lengths equal.
6.2.3 Two Linear Charge Coupled Devices (CCD or diode) Arrays, each located at the focal plane of the displacement
compensating lens. One array is oriented horizontally (for the measurement of azimuthal changes) and the other oriented vertically
(for the measurement of elevation changes). An appropriate element spacing of the arrays is 0.001 in. (0.0254 mm). Using this
element spacing and the 10-in. (254-mm) lens, each diode will represent the equivalent of 0.1 mrad
...
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