<s>
PLate	B-Algorithm
OPtimizer	I-Algorithm
,	O
or	O
PLOP	B-Algorithm
is	O
a	O
CAD	B-Application
program	I-Application
used	O
by	O
amateur	O
telescope	O
makers	O
to	O
design	O
primary	O
mirror	O
support	O
cells	O
for	O
reflecting	O
telescopes	O
.	O
</s>
<s>
However	O
,	O
such	O
calculation	O
does	O
not	O
account	O
for	O
mechanical	O
stresses	O
introduced	O
in	O
one	O
part	O
of	O
a	O
telescope	O
mirror	O
by	O
another	O
part	O
,	O
whereas	O
finite	B-Application
element	I-Application
analysis	I-Application
can	O
be	O
used	O
to	O
reduce	O
such	O
stress	O
.	O
</s>
<s>
Although	O
general	O
finite	B-Application
element	I-Application
analysis	I-Application
programs	O
such	O
as	O
Nastran	B-Algorithm
will	O
work	O
for	O
mirror	O
cells	O
,	O
an	O
advantage	O
of	O
PLOP	B-Algorithm
is	O
that	O
it	O
can	O
be	O
set	O
to	O
ignore	O
deformation	O
that	O
merely	O
results	O
in	O
refocus	O
of	O
a	O
mirror	O
's	O
parabola	O
.	O
</s>
<s>
PLOP	B-Algorithm
can	O
be	O
used	O
to	O
calculate	O
floating	O
support	O
points	O
for	O
a	O
mirror	O
's	O
axial	O
(	O
rear	O
)	O
support	O
;	O
however	O
,	O
additional	O
tools	O
are	O
needed	O
to	O
calculate	O
potential	O
error	O
from	O
a	O
mirror	O
's	O
lateral	O
(	O
edge	O
)	O
support	O
.	O
</s>
<s>
Mirror	O
cell	O
calculations	O
,	O
whether	O
using	O
PLOP	B-Algorithm
or	O
another	O
program	O
,	O
do	O
not	O
overcome	O
errors	O
introduced	O
by	O
gluing	O
the	O
mirror	O
to	O
its	O
cell	O
,	O
excessive	O
tightening	O
of	O
edge	O
supports	O
,	O
nor	O
impingement	O
of	O
the	O
cell	O
structure	O
onto	O
the	O
mirror	O
as	O
result	O
of	O
differential	O
cooling	O
shrinkage	O
.	O
</s>
