The
Aut
hors
-D
avid
Hal
l
●D
avid
Hal
l is a
n El
ectri
cal E
ngin
eer d
esig
ning
el
ectro
nic
circ
uits
for a
lmos
t 30
year
s. M
ost o
f th
at ti
me
was
in th
e ae
rosp
ace
indu
stry
with
B
oein
g/M
cDon
nell-
Dou
glas
in S
t. Lo
uis,
MO
. C
urre
ntly
, he
desi
gns l
aser
ele
ctro
nics
for
Cut
ting
Edge
Opt
roni
cs, I
nc. i
n St
. Cha
rles,
MO
. ●
His
prim
ary
astro
nom
y in
tere
sts a
re o
bser
ving
, cc
d im
agin
g, a
nd a
stro
nom
y re
late
d so
ftwar
e de
velo
pmen
t.
The
Aut
hors
�Jo
hn D
uche
k
●Jo
hn h
as a
doc
tora
te in
Org
anic
Che
mis
try.
He
ha
s bee
n a
prof
esso
r, pi
lot p
lant
man
ager
, pla
nt
troub
lesh
oote
r, an
d la
bora
tory
rese
arch
che
mis
t in
his
ove
r 30
year
s in
the
chem
ical
indu
stry
. H
e cu
rren
tly w
orks
for T
yco-
Hea
lthca
re in
St.
Loui
s, M
O.
●H
is p
rimar
y as
trono
mic
al in
tere
sts a
re
obse
rvin
g an
d ph
otog
raph
y (c
cd a
nd 3
5 m
m).
An
Eyep
iece
Coa
ting
Expe
rimen
t
●Pr
ogra
m su
gges
ts
eyep
iece
s can
be
very
im
porta
nt in
ligh
t los
s in
your
tele
scop
e.
●Th
e co
atin
g ef
fect
iven
ess
�D
epen
ds o
n its
thic
knes
s�
varie
s with
wav
elen
gth
Wha
t do
the
term
s mea
n?
●C
oate
d or
sing
le-c
oate
d: o
ne a
ir-to
-gla
ss
surf
ace(
ATG
S) is
coa
ted
with
a si
ngle
laye
r of
antir
efle
ctio
n m
ater
ial,
usua
lly M
gF2
●Fu
lly C
oate
d: A
ll A
TGS
are
sing
le-c
oate
d
●M
ultic
oate
d: a
t lea
st o
ne A
TGS
surf
ace
has b
een
coat
ed w
ith m
ultip
le la
yers
, the
rest
are
sing
le c
oate
d or
not
coa
ted.
●Fu
lly M
ultic
oate
d: a
ll A
TGS
are
cove
red
with
mul
tiple
co
atin
gs.
Sing
le C
oatin
g (M
gF2)
●Tr
ansm
issi
on d
epen
dent
on
wav
elen
gth,
subs
trate
's in
dex
of
refr
actio
n, th
ickn
ess o
f the
coa
ting,
and
ang
le o
f the
inci
dent
ligh
t
●C
oatin
g is
des
igne
d so
the
rela
tive
phas
e sh
ift b
etw
een
beam
re
flect
ed fr
om u
pper
and
low
er su
rfac
e de
stru
ctiv
ely
inte
rfer
e (c
ance
l)
●O
ptic
al th
ickn
ess m
ust b
e O
DD
NU
MB
ER O
F (λ
/4) w
here
λ is
the
wav
elen
gth
bein
gop
timiz
ed. (
give
s ½λ
path
diff
eren
ce)
●(D
iscu
ssio
n fr
om w
ww
.edm
undo
ptic
s.com
/Tec
hSup
port/
)
MgF
2 C
hara
cter
istic
s
●�T
he p
rinci
ple
of c
oatin
gs is
to re
duce
the
light
refle
ctin
g on
th
e gl
ass s
urfa
ce. I
f the
coa
ting
has a
¼w
avel
engt
h th
ickn
ess
and
the
glas
s an
inde
x of
refr
actio
n hi
gher
than
the
coat
ing
the
2 re
flect
ions
are
in p
hase
opp
ositi
on a
nd c
ance
l. Fo
r 1
mul
ticoa
ted
surf
ace,
the
trans
mis
sion
can
incr
ease
up
to
3.5%
�
Http
://w
ww
.ast
rosu
rf.c
om/
lom
bry/
repo
rts-e
psug
gest
ions
4.ht
ml
How
do
you
know
you
r coa
ting
is
wor
king
as a
dver
tised
?●
Ligh
t Los
ses (
if co
atin
g w
orki
ng p
rope
rly)
�N
o C
oatin
g ~
4% lo
st/s
urfa
ce�
Fully
Coa
ted
~2%
lost
/sur
face
�M
ultic
oate
d ~
1.5%
lost
/sur
face
�Fu
lly M
ultic
oate
d ~
<=1%
lost
/sur
face
●¼
of 5
50 n
m is
0.0
0000
0137
met
ers o
r 137
0 an
gstro
ms.
One
MgF
2 m
olec
ule
is ~
2.5
Ang
stro
ms..
.. co
atin
g sh
ould
be
550
mol
ecul
es th
ick.
●If
the
coat
ing
is tw
ice
as th
ick,
the
wav
es w
ill
rein
forc
e, n
ot c
ance
l. T
he th
ickn
ess i
s crit
ical
!!!!
The
Expe
rimen
t
●U
sing
an
optic
al b
ench
, eq
uipp
ed w
ith a
gre
en
lase
r (55
0 nm
), m
easu
re
the
% tr
ansm
ittan
ce o
f a
varie
ty o
f eye
piec
es.
●D
ave
Hal
l had
acc
ess t
o th
e ne
cess
ary
equi
pmen
t at
his j
ob a
t CEO
lase
rs.
Set u
p●
Lase
r is o
n th
e rig
ht.
●Th
e ey
epie
ce to
be
test
ed is
just
in
fron
t of t
he
dete
ctor
.
●D
ave
is a
djus
ting
the
dete
ctor
to
colle
ct th
e w
hole
lig
ht b
eam
.
Expe
rimen
tal L
imita
tions
●W
e fo
und
that
we
wer
e un
able
to g
et c
onsi
sten
t re
sults
on
any
eyep
iece
s un
der 1
0mm
, pro
babl
y be
caus
e w
e co
uldn
't
get t
he le
ns c
lose
en
ough
to th
e de
tect
or
to g
et a
ll th
e lig
ht
●12
mm
resu
lts sh
ould
be
take
n w
ith a
gra
in o
f sa
lt.
The
met
hod
for e
ach
eyep
iece
(1)
●M
easu
re th
e da
rk
volta
geV
dan
d th
e lig
ht v
olta
geV
lwith
no
eye
piec
e in
pla
ce.
●Th
e to
tal v
olta
geV
t=V
l-Vd
●Pu
t the
eye
piec
e in
.
The
met
hod
for e
ach
eyep
iece
(2)
●Ta
ke 5
vol
tage
re
adin
gs fo
r eac
h ey
epie
ce a
fter r
otat
ing
the
eyep
iece
90
degr
ees.
(ver
ify th
at 1
st
and
last
are
the
sam
e)
●A
vera
ge th
e 4
read
ings
an
d su
btra
ctV
dfr
om
the
aver
age
to g
et (V
a)
●%
tran
smitt
ance
=
(Va/
Vt)*
100
1.25
� Ey
epie
ce R
esul
tsBr
and
Mode
lTy
peFL
mm
Coat
ings
# of
lens
% tr
ans
Com
men
ts
Tele
-Opt
ics
Kelln
erKe
llner
40??
?3
or 4
98.6
Cel
estro
nO
rthos
copi
cO
rthos
copi
c25
Fully
coa
ted
98.2
Uni
vers
ity O
ptic
sO
rthos
copi
cO
rthos
copi
c25
Mul
ti-co
ated
97.3
Orio
n U
ltras
copi
cO
rthos
copi
c20
Mul
ti-co
ated
97.1
Mea
deSu
perP
loss
lPl
ossl
26M
ulti-
coat
ed95
.7U
nive
rsity
Opt
ics
Orth
osco
pic
Orth
osco
pic
18M
ulti-
coat
ed95
.7O
rion
Ultr
asco
pic
Orth
osco
pic
25M
ulti-
coat
ed95
.595
.00%
Orio
n Si
rius
Plos
sl26
Fully
coa
ted
94.5
No-
nam
e
Er
fleEr
fle32
???
94.2
1.25
"O
rion
Siriu
sPl
ossl
17Fu
lly c
oate
d92
.0Te
le-O
ptic
sTe
le-O
ptic
Kelln
er18
???
3 or
491
.6C
eles
tron
Ulti
ma
Mod
ified
plo
ssl
24Fu
lly m
ultic
oate
d4
to 5
91
.3C
eles
tron
(repe
at)
Ulti
ma
Mod
ified
plo
ssl
18Fu
lly m
ultic
oate
d4
to 5
90
.9R
epea
t of s
ame
lens
Cel
estro
nU
ltim
aM
odifi
ed p
loss
l30
Fully
mul
ticoa
ted
4 to
5
90.8
Cel
estro
nU
ltim
aM
odifi
ed p
loss
l18
Fully
mul
ticoa
ted
4 to
5
89.8
Uni
vers
ity O
ptic
sKo
nig
Koni
g32
Mul
ti-co
ated
89.2
1.25
"C
eles
tron
Ulti
ma
Mod
ified
plo
ssl
35Fu
lly m
ultic
oate
d4 t
o 5
87.1
Uni
vers
ity O
ptic
sO
rthos
copi
cO
rthos
copi
c12
.5M
ulti-
coat
ed86
.5C
eles
tron
Ulti
ma
Mod
ified
plo
ssl
12.5
Fully
mul
ticoa
ted
4 to
5
86.3
Cel
estro
nPl
ossl
Plos
sl26
Mul
ti-co
ated
85.5
Cel
estro
nU
ltim
a(D
iff. L
ensM
odifi
ed p
loss
l12
.5Fu
lly m
ultic
oate
d4
to 5
84
.6D
iffer
ent l
ens
Apog
eeEr
fleEr
fle17
.581
.4Ju
nky
lens
No
nam
eKe
llner
Kelln
er17
.5??
?74
.2Ju
nky
lens
2� E
yepi
ece
Res
ults
Bra
ndM
odel
Type
FL m
mC
oatin
gs#
of le
nses
% t
rans
Hom
e-m
ade
Erfle
Erfle
27??
?5
97.5
Edm
und
Scie
ntific
Erfle
Erfle
32??
??
90.9
Uni
vers
ity O
ptics
Kon
igK
onig
32M
ulti-
coat
ed?
88.2
Hom
e-m
ade
Rin
iEr
fle55
???
?81
.1R
usse
llK
onig
Kon
ig19
Blue
coa
ting
?79
.6H
ome-
mad
eR
ini
Erfle
45??
??
78.4
Con
clus
ions
●Th
e 12
mm
resu
lts a
re su
spec
t�th
ey a
re
clus
tere
d at
a lo
w v
alue
. Tr
ansm
issi
on
over
pow
ered
by
light
loss
es (l
ight
mis
sing
de
tect
or).
●Fu
lly m
ultic
oate
d di
d no
t far
e w
ell i
n th
is te
st
(85-
90%
)●
Mul
ticoa
ted
orth
osco
pics
, and
par
ticul
arly
UO
or
thos
copi
cs a
re su
perio
r at h
igh
light
tra
nsm
issi
on (9
5-98
%)
