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

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rion

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sPl

ossl

17Fu

lly c

oate

d92

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le-O

ptic

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le-O

ptic

Kelln

er18

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3 or

491

.6C

eles

tron

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ma

Mod

ified

plo

ssl

24Fu

lly m

ultic

oate

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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

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estro

nU

ltim

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odifi

ed p

loss

l30

Fully

mul

ticoa

ted

4 to

5

90.8

Cel

estro

nU

ltim

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odifi

ed p

loss

l18

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mul

ticoa

ted

4 to

5

89.8

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vers

ity O

ptic

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nig

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ti-co

ated

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1.25

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tron

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ma

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ified

plo

ssl

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lly m

ultic

oate

d4 t

o 5

87.1

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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

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sl26

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ti-co

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lly m

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to 5

84

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iffer

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fle17

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nam

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llner

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er17

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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

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ntific

Erfle

Erfle

32??

??

90.9

Uni

vers

ity O

ptics

Kon

igK

onig

32M

ulti-

coat

ed?

88.2

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e-m

ade

Rin

iEr

fle55

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usse

llK

onig

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ig19

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coa

ting

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ome-

mad

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ini

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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

%)