1 - NGA

d~lacemenf increasing with the thickness of
the tens.
optical cormlatlon-The process of
ekcfronicatfy relsting a stored @refoWaPhk film
~! of a geographc arm with a reaftima opticsl
_ =Wird by phofogrephc or telsv”b
sensors. H is used to provide poeitiiing
information to CUTeCl or check air nevic@On
and guidence eyaerns.
optkal danalty-A consnon logarithm of
mciprod of tmmmiftance.
optlcd ffst-A surfeoe, usuelfy of glass,
ground end peliihed pfans within a fraction of e
wavelength of fight. Art eptbel eternent or gfase
blank with en cptical fiat is used to 1ss1 the
flatness of other suriaces, Atso called fist;
optical plan..
optical parallex—See Instrument
perellex, definition 1.
optlcel psth-The path followed by e my of
light thrwgh en eptical system.
optical plnne-See optical flat.
optical plummst —See vertlcel collimator.
opticel rectificetlohl%e process of
projecting lha image af e fitted eerial
photograph onto a horiiorrtal reference pfans to
eliminate ths imags dbplscements ceused by
tin of the aerisl csmers eI the time of exposure.
optical square-A emall trend instrument
urd in setting oft e righl engle. One form of
eptiml squsre uses two plane minors placed at
an angle of 45° to eech other. In use, one
otjacl is alghted dhct, and another object is so
pfsced thal ifs fwice-reffected imege appaars
directly in fins with the first object. The lines to
the point of observation from the w observed
objects wifl then meet in a right engle. In
mother form IX optical square, e single pbne
mintrr is so ptsced thst d makes en engle of 4S”
with e sighting line; one ~jecf is sighted direct,
and the dher so plead tfrd its rafiected image
is seen alse in tha sighting line.
optical ●ystarn-All the parts of a compound
lens end acoassory o@icsl perts which ere
designed to corrtribule to the formation of an
imege on s phomgrsphn emulaiin, w of e
visual image, or of an image on a projection
screen.
MI L-HDBK-B50
optkal vemfsr-A mkroscope with vernier
Iii ruled on e gleas elide pfscad in the fccel
plane conunon 10 the cbjective end the
ey@ace, where if is corrpered wdh the image
of the grsdusted circle.
optical Wodg-ee wedga.
optical-machanbal soanner-A system
ufifizing a rc4ating - ard a dahxfor in
conjunction with knses and prisms to record
raflerled ardor emitted eldromagrdic energy
in a scsnni~ mods IIkenS the ffigtrf peth.
optical-projection lnatrumenta—A ckss of
instruments which provide pmjectsd kwgae d
photographic prints or &her opeque meleriel
superfmpeaed on a mep or msp manuscript.
Often ussd fer transferring detsil from nesrverticd
photographs or other seurce material.
optimum ground ●lovatlon—
(phetogrammatry) The efe.ation of an assumed
herizentel surfem in Ihe eraa photographed that
would be pmjeckf at Ihe optimum distance in
the pfotting instrument.
orbitei aftitude-The mean altitude above
Ihe surfece of the psrent bedy of the orbii C4 e
astellile.
orbital elemOnts-A set of sk parameters
defining the orbii et a body eftrected by a
central ferce.
orbltsl Irrclirratlon-lhe direction thet the
path of an ofiiing body tekaa. In the case of an
Eerth setetfiie, ths psth may be defined by the
angle of irdinstii of the peth to the Equator.
orbital mode-A methed for determining the
peaition of en unknown station posifien men
the unknewm podtiin arrmt be viewed
aimutfenmusly with known pdf!k.ns. The arc of
the ssteliite otbit is axtrapoleted from the
ephemeris of the setellife determined by the
known stetions wtich permits the determination
of the position of the unknown stetbn
dependent completely en the =tellife’s orbital
parameter.
orbltel motion-Continuous motion in .x
clcssd peth about and as a dkd resuff of a
source of gravitational aftractbn.
ortrltal path-One of the trecks on a primary
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