<s>
A	O
helmet-mounted	B-Application
display	I-Application
(	O
HMD	O
)	O
is	O
a	O
headworn	O
device	O
that	O
uses	O
displays	O
and	O
optics	B-Algorithm
to	O
project	O
imagery	O
and/or	O
symbology	O
to	O
the	O
eyes	O
.	O
</s>
<s>
The	O
display-optics	O
assembly	O
can	O
be	O
attached	O
to	O
a	O
helmet	O
or	O
integrated	O
into	O
the	O
design	O
of	O
the	O
helmet	O
.	O
</s>
<s>
An	O
HMD	O
provides	O
the	O
pilot	O
with	O
situation	O
awareness	O
,	O
an	O
enhanced	B-Device
image	I-Device
of	O
the	O
scene	O
,	O
and	O
in	O
military	O
applications	O
cue	O
weapons	O
systems	O
,	O
to	O
the	O
direction	O
their	O
head	O
is	O
pointing	O
.	O
</s>
<s>
Applications	O
which	O
allow	O
cuing	O
of	O
weapon	O
systems	O
are	O
referred	O
to	O
as	O
helmet-mounted	B-Application
sight	I-Application
and	O
display	O
(	O
HMSD	O
)	O
or	O
helmet-mounted	B-Application
sights	I-Application
(	O
HMS	O
)	O
.	O
</s>
<s>
using	O
the	O
head	O
angle	O
as	O
a	O
pointer	O
to	O
direct	O
air-to-air	O
and	O
air-to-ground	O
weapons	O
seekers	O
or	O
other	O
sensors	O
(	O
e.g.	O
,	O
radar	B-Application
,	O
FLIR	O
)	O
to	O
a	O
target	O
merely	O
by	O
pointing	O
his	O
head	O
at	O
the	O
target	O
and	O
actuating	O
a	O
switch	O
via	O
HOTAS	B-Algorithm
controls	O
.	O
</s>
<s>
displaying	O
targeting	O
and	O
aircraft	O
performance	O
information	O
(	O
such	O
as	O
airspeed	O
,	O
altitude	B-Application
,	O
target	O
range	O
,	O
weapon	O
seeker	O
status	O
,	O
"	B-Application
g	I-Application
"	I-Application
,	O
etc	O
.	O
)	O
</s>
<s>
In	O
1962	O
,	O
Hughes	O
Aircraft	O
Company	O
revealed	O
the	O
Electrocular	O
,	O
a	O
compact	B-Device
CRT	I-Device
,	O
head-mounted	O
monocular	O
display	O
that	O
reflected	O
a	O
TV	O
signal	O
onto	O
a	O
transparent	O
eyepiece	O
.	O
</s>
<s>
,	O
Mirage	O
3CZ	O
and	O
Mirage	O
F1AZ	O
of	O
the	O
SAAF	O
(	O
South	O
African	O
Air	O
Force	O
)	O
was	O
the	O
first	O
to	O
use	O
a	O
locally	O
developed	O
helmet	B-Application
mounted	I-Application
sight	I-Application
.	O
</s>
<s>
South	O
Africa	O
was	O
the	O
first	O
country	O
to	O
develop	O
and	O
use	O
HMSs	O
in	O
combat	O
,	O
a	O
locally	O
developed	O
helmet-mounted	B-Application
sight	I-Application
integrated	O
with	O
the	O
Armscor	O
V3A	O
heat	O
seeking	O
missile	O
.	O
</s>
<s>
These	O
rudimentary	O
devices	O
were	O
better	O
described	O
as	O
Helmet-Mounted	B-Application
Sights	I-Application
.	O
</s>
<s>
weight	O
and	O
balance	O
–	O
total	O
helmet	O
weight	O
and	O
its	O
center	O
of	O
gravity	O
,	O
which	O
are	O
particularly	O
important	O
under	O
high	O
"	B-Application
g	I-Application
"	I-Application
maneuvers	O
.	O
</s>
<s>
optical	O
characteristics	O
–	O
calibration	O
,	O
sharpness	O
,	O
distant	O
focus	O
(	O
or	O
'	O
Collimation	O
 '	O
,	O
a	O
technique	O
used	O
to	O
present	O
the	O
images	O
at	O
a	O
distant	O
focus	O
,	O
which	O
improves	O
the	O
readability	O
of	O
images	O
)	O
,	O
monocular	O
vs.	O
binocular	B-Algorithm
imagery	O
,	O
eye	O
dominance	O
,	O
and	O
binocular	B-Algorithm
rivalry	O
.	O
</s>
<s>
HMD	O
designs	O
must	O
sense	O
the	O
orientation	O
(	O
elevation	O
,	O
azimuth	O
and	O
roll	O
)	O
and	O
in	O
some	O
cases	O
the	O
position	O
(	O
x	O
,	O
y	O
,	O
and	O
z	O
)	O
of	O
the	O
pilot	O
's	O
head	O
relative	O
to	O
the	O
airframe	O
with	O
sufficient	O
precision	O
even	O
under	O
high	O
"	B-Application
g	I-Application
"	I-Application
,	O
vibration	O
,	O
and	O
during	O
rapid	O
head	O
movement	O
.	O
</s>
<s>
The	O
Cobra	O
HMD	O
as	O
used	O
on	O
both	O
the	O
Eurofighter	B-Application
Typhoon	I-Application
and	O
the	O
JAS39	O
Gripen	O
both	O
employ	O
the	O
optical	O
helmet	O
tracker	O
developed	O
by	O
Denel	O
Optronics	O
(	O
now	O
part	O
of	O
Zeiss	O
Optronics	O
)	O
.	O
</s>
<s>
Older	O
HMDs	O
typically	O
employ	O
a	O
compact	B-Device
CRT	I-Device
embedded	O
in	O
the	O
helmet	O
,	O
and	O
suitable	O
optics	B-Algorithm
to	O
display	O
symbology	O
on	O
to	O
the	O
pilot	O
's	O
visor	O
or	O
reticle	O
,	O
focused	O
at	O
infinity	B-Application
.	O
</s>
<s>
Modern	O
HMDs	O
have	O
dispensed	O
with	O
the	O
CRT	B-Device
in	O
favor	O
of	O
micro-displays	O
such	O
as	O
liquid	B-Device
crystal	I-Device
on	I-Device
silicon	I-Device
(	O
LCOS	B-Device
)	O
or	O
liquid	B-Device
crystal	I-Device
display	I-Device
(	O
LCD	B-Device
)	O
along	O
with	O
an	O
LED	O
illuminator	O
to	O
generate	O
the	O
displayed	O
image	O
.	O
</s>
<s>
Additionally	O
,	O
it	O
has	O
been	O
certified	O
on	O
the	O
F/A	B-Application
-18	I-Application
and	O
F-5	O
.	O
</s>
<s>
A	O
quick-disconnect	O
wire	O
powers	O
the	O
display	O
and	O
carries	O
video	O
drive	O
signals	O
to	O
the	O
helmet	O
's	O
Cathode	B-Device
Ray	I-Device
Tube	I-Device
(	O
CRT	B-Device
)	O
.	O
</s>
<s>
The	O
Navy	O
conducted	O
RDT&E	O
on	O
the	O
F/A	O
-18C	O
as	O
lead	O
platform	O
for	O
JHMCS	O
,	O
but	O
fielded	O
it	O
first	O
on	O
the	O
F/A	B-Application
-18	I-Application
Super	O
Hornet	O
E	O
and	O
F	O
aircraft	O
in	O
2003	O
.	O
</s>
<s>
Boeing	O
integrated	O
the	O
system	O
into	O
the	O
F/A	B-Application
-18	I-Application
and	O
began	O
low-rate	O
initial	O
production	O
delivery	O
in	O
fiscal	O
year	O
2002	O
.	O
</s>
<s>
The	O
CRT	B-Device
package	O
is	O
more	O
capable	O
,	O
but	O
remains	O
limited	O
to	O
monochrome	O
presentation	O
of	O
cursive	O
symbology	O
.	O
</s>
<s>
In	O
March	O
2009	O
,	O
a	O
successful	O
'	O
Lock	O
on	O
After	O
Launch	O
 '	O
firing	O
of	O
an	O
ASRAAM	O
at	O
a	O
target	O
located	O
behind	O
the	O
wing-line	O
of	O
the	O
‘	O
shooter	O
 '	O
aircraft	O
,	O
was	O
demonstrated	O
by	O
a	O
Royal	O
Australian	O
Air	O
Force	O
(	O
RAAF	O
)	O
F/A	B-Application
-18	I-Application
using	O
JHMCS	O
.	O
</s>
<s>
TopNight	O
,	O
a	O
Topsight	O
derivative	O
,	O
is	O
designed	O
specifically	O
for	O
adverse	O
weather	O
and	O
night	O
air	O
to	O
ground	O
operations	O
,	O
employing	O
more	O
complex	O
optics	B-Algorithm
to	O
project	O
infrared	O
imagery	O
overlaid	O
with	O
symbology	O
.	O
</s>
<s>
The	O
Eurofighter	B-Application
Typhoon	I-Application
utilizes	O
the	O
Helmet-Mounted	O
Symbology	O
System	O
(	O
HMSS	O
)	O
developed	O
by	O
BAE	O
Systems	O
and	O
Pilkington	O
Optronics	O
.	O
</s>
<s>
Vision	O
Systems	O
International	O
(	O
VSI	O
;	O
the	O
Elbit	O
Systems/Rockwell	O
Collins	O
joint	O
venture	O
)	O
along	O
with	O
Helmet	O
Integrated	O
Systems	O
,	O
Ltd	O
.	O
developed	O
the	O
Helmet-Mounted	B-Application
Display	I-Application
System	O
(	O
HMDS	O
)	O
for	O
the	O
F-35	O
Joint	O
Strike	O
Fighter	O
aircraft	O
.	O
</s>
<s>
The	O
Helmet-Mounted	B-Application
Display	I-Application
System	O
was	O
fully	O
operational	O
and	O
ready	O
for	O
delivery	O
in	O
July	O
2014	O
.	O
</s>
<s>
Direct	O
retinal	B-General_Concept
projection	I-General_Concept
–	O
Systems	O
that	O
project	O
information	O
directly	O
onto	O
the	O
wearer	O
's	O
retina	O
with	O
a	O
low-powered	O
laser	O
(	O
virtual	B-General_Concept
retinal	I-General_Concept
display	I-General_Concept
)	O
are	O
also	O
in	O
experimentation	O
.	O
</s>
