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Патент USA US2410720

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NOV. 5, 1946.
G_ L, D|MM|¢K
2,410,720
LENS COATING APPARATUS
Filed Nov. 22, 1943
4 Sheets-Sheet l
ELEM LDIMMIEK
@935 g
(Tirol-m1}
Nov. 5, 1946.
G, L,‘D|MM|¢K
2,410,720
LENS COATING APPARATUS
Filed NOV. 22, 1943
4 Sheets—Sheet 2
Smwutor
GLENN %.DIMMIEK
mtorucgt
Patented Nov. 5, 1946
2,410,720
umrso s'm'ras PATENT OFFICE
2,410,120’
LENS COATING APPARATUS
Glenn Leslie Dlmmick, Indianapolis, 11:11., as
signor to Radio Corporation of America, a cor
poration of Delaware
Application November 22, 1943, Serial No. 511,231
14 Claims. (Cl. iii-12.2)
1
2
uum-tlght seal against the base plate l0, The
vacuum-tight tit of this bell jar may be secured
by grinding, sealing or packing. It is most con
ducing their re?ection, increasing their re?ec
tion, or rendering them selectively re?ective.
veniently secured by a layer of semi-plastic gas
The apparatus involves means‘for applying coat 5 ket material between the bell Jar and the base
plate. Appropriate means for evacuating the bell
ings of magnesium ?uoride, zinc sulphide, or
jar are provided, preferably of the type generally
other materials for such purpose.
disclosed in the application of L. T. Sachtleben,
The apparatus includes a vacuum chamber,
means for evacuating the chamber, means for
?ied on October 29, 1943, Serial No. 508,267, al
though any other suitable means may be pro
holding the optical elements to be coated, and
vided. The lenses or other optical elements are
means for applying the coating thereto, and to
held in appropriate work holder l3 which may
gether with means for securing accurate distri
be reversed in position by the magnetic means
bution with the coating and means for distribut
ll, moved by the exterior magnet M. The work
ing the coating on either side of the elements
being treated.
15 holder I3 is in a. position parallel to the base in
when the lenses are being, treated. The work
One object of the invention is to provide a
holder I3 is supported by a ring it carried on
method of and means for applying uniformly dis
a set of three legs l2 resting on top of the base
tributed coating to an optical surface.
In. When the vacuum is reduced to an appropri
Another object of the invention is to provide
apparatus for selectively applying di?’erent coat 20 ate point the optical surfaces are treated with
ionized gas produced by ionizing the remaining
ing materials.
gas by the magnesium electrodes 21 which are
Another object oi‘ the invention is to provide
supplied with alternating current at an appropri
apparatus for placing the different evaporators
ate voltage.
‘
of coating materials in proper relation to the
25 The material to be evaporated on to the sur
optical elements being treated.
face of the optical elements is placed in the plat
Other and incidental objects of the invention
inum or molybdenum boats l6, I1, or ill, see also
will be apparent from a reading of the following
This invention relates to an apparatus for
coating optical elements for the purpose of re
speci?cation and an inspection of the accom
panying drawings in which:
Figure l is a perspective view of the apparatus,
Figure 2 is a plan view looking down on the
middle or the base plate,
Figure 8 is a view from the right-hand side
of P18‘. 2,
Figs. 2 and 3. Filaments may be substituted for
these boats in case a material is to be used which
evaporates properly from the ?laments. It is
necessary, in order to secure a uniform distribu
tion of the evaporated material over the work
holder II, to have the evaporating boats aligned
substantially with the middle of the work holder.
Figure 4 is a distribution curve of evaporated 35 If the work is to be coated with two or more dif—
ferent materials it is therefore necessary that
the boats be moved into axial alignment selec
Figure 5 is one type of diil'usion screen for
tively. The boats l6, I1 and iii are secured on
producing a proper distribution of the evaporated
a plate I! and are connected to the terminals 26
material,
Figure 6 is a curve showing the shape of one 40 by appropriate wires 31 so that the boats may
be selectively heated. The plate l9 may be of
half of a correcting plate,
an appropriate insulating material to prevent
‘ Figure 7 is a curve of the radius of the lens
short-clrcuiting the boats, or it may be metallic
plate plotted against the percentage out evap
and have the boats secured thereto by appropriate
orated material with the distance to the evaporat
material,
ingboatteninches,
Figure 8 corresponds to Fig. 7 except that the
distance to the evaporating. boat is nine inches,
45 insulating connections. The plate I9 is carried
on the arm 20 which may be pivoted on one of
the legs l2 Or on some other equivalent support.
and
The arm 20 is re-curved to form the movable
arm 23 which is actuated by the arm 2| . The
Figure 9 is a diagram of the outline of a solid
50 1am 2| is pivoted at 25 at substantially the center
correcting plate based on the curve of Fig. 8.
of the base plate Ill and of the bell jar H. An
Referring first to Fig. 1, It! indicates the base
armature 22 is secured to the end of the arm 2|
plate which may be or! any appropriate material
and moves within the bell Jar I I reasonably close
but for reasons of convenience it is preferably
to the surface thereof. By reason of the pivot
of steel and of a diameter upwards of 12 inches.
ll indicates a bell Jar adapted to fit with a vac 55 mini ‘ll the arm ii, the armature 22 moves sub
9,410,?”
3
'
stantially parallel with the bell jar and is moved
from position to position by the external mag
net M which may be an electro-magnet or a '
4
by a motor 8'. when the motor I! is operated.
the magnet 8| rotates at the same speed, there
by causing rotation of the armature I. and
permanent magnet. The arm 2| is connected
shaft a ‘and causing rotation of the ring Ii '
to the arm 21 by a sliding pivot at 24. The plate 5 which carries the shutter ll around the axis of
I! is secured in the several positions of the boat
transmission of the coating to the work holder
by a spring latch 20 carried on the base plate 2|
or lens plate It.
'
which is supported above the base of the bell jar
In Fig. 8 there is shown in solid lines the rel
and to which the pivot of the arm II is also se
ative amount of coating transmitted to the work
cured.
10 holder or lens plate when the work holder or
The thickness of the coating varies according
lens plate is at a distance of 9" from the evap
to the distance from the evaporating boat to the
crating boat. It will be noted that from 100%
lens plate or work holder. In my application.
at the center of the work holder or lens plate
Serial No. 468,915, I disclosed one method of com
the transmission falls to ‘15% at a radius of 8%"
pensating for this effect by using three separate 15 and the difference between these two percentages
similar boats and a triangular wire screen. In
represents the amount for which correction is
the present arrangelheat the use or three sepa- , required. -The dotted lines represent the amount
rate similar boats is not practical in view of the
of correction required, and the development of
fact that layers of different materials are to be
the correction is shown in Fig. 9 as applied to the
deposited during one evacuation of the jar.
20 correcting plate to and as tabulated at the bot
One arrangement for securing uniform spread
tom of Fig. 8. It will be noted that the width
ing of the evaporating material is shown in Figs.
of the correcting plate is inversely proportional
4 and 5. In Fig. 4 is plotted the distribution of.
to the normal distribution of the evaporated ma
material against the radius of the lens plate
terial and that therefore a uniform distribution
indicated as b when the lens plate is at a dis
is secured.
.
tance of 6" from the evaporating boat plotted
It has already been noted froma considera
on the basis of 100% of evaporating material at
tion of Fig. 8 that the thickness of the coating
the center of the lens plate. If a screen is de
deposited at a point 3% inches from the center
signed in accordance with the attenuation of the
of the lens plate is only '75 per cent of that de
material at the edges as shown in Fig. 5, this 80 posited at the center. In other words, to e?ect
screen will compensate for the distribution of
uniform coating the shutter 80 should obstruct
the material if the screen is rotated about its
25 per cent of the vapor from reaching the cen
central point C during the evaporation of the
ter of the lens plate, and not aiford any obstruc
material in the manner which will be herein
tion at all to vapor which is to reach points 3%
after described.
85 inches from the center; but the radius of the
Although the screen may be satisfactory for
lens plate at. its center is in?nitesimally small,
thick coatings, it is not completely satisfactory
and so, therefore, is its circumference. The
for very thin coatings or coatings whose thick
zone to be shielded from vapor at the center of
ness must be accurately determined, for the rea-.
the lens plate is, therefore, negligible and the
son that often the screen is not unform, it is dif
iicult to cut with uniformity, it becomes grad
ually coated with deposited material which
40 width of the shield is thus zero at both of its
ends. To take another example, Fig. 8 shows
that approximately 23 per cent and 17 per cent
changes its transmission, and at the closely ad
of the vapor is to be prevented from reaching
Jacent parts of the screen it may interfere with
points respectively one inch and two inches from
the transmission of material more than the 45 the center; but the circumferential zone to be
amount calculated.
protected at a distance of two inches from the
I have devised a solid shutter which avoids
center is twice as great as that which is only one
the deficiency of the screen above described and
inch away, and the blade or shutter 3| must.
is operated in the same manner. This solid shut
therefore, be so designed as to have widths at
ter uses a single blade instead of multiple blades 50 points respectively one inch and two inches from
of the screen, and it can accordingly be rotated
the center which are in the proportion 23:34.
at such a speed that one rotation will not inter
The same considerations apply in determining
fere with the passage of the coating material
the width of the blade at all other points from
during preceding or subsequent rotations. The
the center, and inspection of ‘Fig. 9 reveals that
rotating mechanism is shown in Fig. 1. The 55 it has been so designed.
shutter or blade so is mounted on a ring M, which
One other factor to be taken into considera
is considerably larger than the articles to be
tion in designing the blade is that the blade lll
coated, and of approximately the same diameter
is nearer to the evaporating boat than the lens
as the support i5, being slightly smaller so that
plate. In the example from which the data of
it can rotate within the limits of the supports 60 Fig. 8 was obtained, the lens plate It was nine
l2. On two of the supports I! there are mount
inches from the evaporating boat while the blade
ed rollers 32 which support the ring 3|. These
II) was only 5% inches away, and the width of
rollers may be of brass but are preferably of
the blade is, therefore. reduced in the propor
brass with small rubber tires to prevent vibra
tion 18:11 at all points along its axial length.
tion of the apparatus. On the third leg there is so The blade is, of course, symmetrical about the
mounted a bearing 37 which carries a shaft 33.
horizontal axis‘marked "0" in Fig. 9, and is gen
The shaft carries on its inner end a roller sub
erally elliptical in shape.
stantially identical with the rollers 32 and drives
The following is a more particular example of
that roller to rotate the ring SI. On the outer
how the attenuating blade may be designed to
end of the shaft 33 there is located an iron or 70. meet a given situation. ‘
»
steel member 34 which is preferably of a sub
As shown by the diiferences in Figs. 4, "I, and 8
stantially U shape and is supported to rotate
the distribution curve of a material evaporated
Just within the bell jar ll. Outside of the bell
from a point source to a given surface will vary
jar there is located a magnet 35 which is adapt
with the distance from the source to the sur
ed to drive the armature “34 and which is driven 75 face. Figs. 4, 7, and 8 are distribution curves
11,410,790
5
.
iordistaneesoisix.ten,andnineinchesrespec
tively.
These curves may be calculated with
6
oithe circumierenceotacirclehavinguid
plate is round simply by Iu?tiplrins the length
radius by the percent attenuation desired at that
' the aid of the formula
point. For example, at a radius oi’ 0.00 inch
on the correcting plate the correction required,
asreadtrornthedottedline curveoil'lg.l,is
which formula, as explained more fully in store
aboutzapercent. Thecircumierenceoiacircle
inentioned Dlmmick application, Serial No. 468,
having a radius of 0.80 inch is about 3.71‘ inches.
915, enables one to iind the thickness of an
'rakingiiapercentoithisvaluegivesaresult
evaporated him at any point. 0! course. when 10 of about .87 inch which corresponds with' the
the thickness or the illm at any point is known,
valueasplottedinl'ig.9. Allotherpointson
the percent attenuation compared with a point
thecurvesoiFig.9arecalculatedinasim?ar
directly opposite the center of .the evaporator
manner.
can also be easily found.
'Iheaboveiigureswerecalculatedonthehasis
Taking the curve shown in Fig. 8 it is seen
of obtaining a uniiorm coating. If some other
that for a lens plate positioned nine inches from
distribution of coating. 1. e., attenuation, were
an evaporating boat, the thickness of a coating
desired, the shape of the blade could be calcu
3% inches i'rom the center of the plate is only 75
lated in an analogous manner.
per cent of the thickness at the center. At a dis
I claim as my invention,
tance of 2 inches the thickness is about 92 per 20
1. In a vacuum coating apparatus, a work
cent, at a distance 01' 1 inch. about 98 percent,
holder and plurality of evaporating means,
and so on. In other words the percent attenua
means for selectively shiiting each of the evap
tion at these three points is about 25 percent.
orating means into axial alignment with the
8 percent, and 2 percent respectively. To ?nd the
work holder from the exterior oi’ the device, and
amount of correction which a correcting device 25 means for selectively actuating the evaporating
should supply at each oi’ these points in order to
means thus aligned.
provide a uniform coating it is only necessary to
2. In a vacuum coating apparatus, a work
subtract each of the above values from 25 per
holder and plurality of evaporating means,
cent (the maximum attenuation in this instance).
magnetic means for selectively shitting each of
Subtracting we get the values 0, 1'7, and 23. 30 the evaporating means into axial alignment with
These values fall on the dotted line curve of
the work holder from the exterior oi’ the device.
Fig. 8.
and means for selectively actuating the evap
Obviously, the correcting blade cannot be
placed in exactly the same plane as the plane of
orating means thus aligned.
3. In a vacuum coating apparatus, a work
the surface being coated. It may, however, be 35 holder and a carrier carrying a pluraliliy oil
placed at any convenient distance therefrom. In
the example of Fig. 8, the correcting blade was
placed at a distance of 5% inches from the evap
evaporating means, means for shifting the car
of a cone (in this case inverted.)
41. In a vacuum coating apparatus, a work
holder and a carrier carrying a plurality of
rier from the exterior of the apparatus to shift
each of the evaporating means selectively into
orating boat.
axial alignment with the work holder, and means
Evaporated material travelling from an evap 40 for selectively actuating the evaporating means
orating boat to a surface spreads out in the form
thus aligned.
A correcting
blade placed somewhere between the apex and
the base of this cone would have a radius which
is dependent upon its position. That is, the ratio
evaporating means, magnetic means for shifting
the carrier from the exterior of the apparatus
of the radius of the blade to the radius of the
surface being coated is the same as the ratio
of the distance between the evaporator and the
1y into axial alignment with the work holder,
to shift each of the evaporating means selective
and means for selectively actuating the evapo
blade to the distance between the evaporator and
rating means thus aligned.
the surface. In the example shown in Fig. 8 50
5. In a vacuum coating apparatus, a work hold
the latter ratio is seen to be Eat/2:9 or 11:18.
er, a plurality of evaporating means, means for
Multiplying any given radius oi‘ the lens plate,
as found at the bottom of Fig. 8, by this ratio,
gives the corresponding radius of the correcting
plate. For instance the length of correcting 55
shifting each of said evaporating means selectively
into axial alignment with the work holder and for
selectively actuating the evaporating means thus
blade corresponding to a lens plate having a
radius of 31/2 inches equals 31/2 multiplied by
orating means and the work holder for securing
uniform distribution of the evaporated material.
11/18 or 2.14 inches. For values of 2 inches and
1 inch on the lens plate, the corresponding values
6. In a vacuum coating apparatus, a work hold
er, a plurality of evaporating means, means for
aligned, and rotatable means between the evap
on the correcting plate are seen to be 1.22 and 60 shifting each of said evaporating means selec
0.60 inches.
tively into axial alignment with the work holder
To further investigate the example of Fig. 8
and for selectively actuating the evaporating
and obtain enough points to plot a smooth curve
means thus aligned, rotatable means between the
such as shown in Fig. 9, a number of points
evaporating means and the work holder for se
along the radius of the lens plate or converted 65 curing uniform distribution 01' the evaporated ma
to the corresponding values along the radius of
terial, and means for reversing the position of the
the correcting plate by multiplying the former
work holder-to expose the other side oi’ the work.
7. In a vacuum coating apparatus a work
values by 11/18. A series of these calculated
values is shown at the bottom of Fig. 8 imme~
holder, a. plurality oi.’ evaporating means mounted
diately above the caption “Radius of correcting 70 on a carrier. means or shifting the carrier from
plate.’
the exterior of the apparatus to shift each of
the evaporating means selectively into axial align
As mentioned previously, Fig. 9 shows the
actual values for a correcting plate constructed
ment with the work holder, means for selectively
to fit the example of Fig. 8. The circumferen
actuating the evaporating means thus aligned,
tial width at any given radius of the correcting 75 rotatable means between the evaporating means
2,410,120
7
and the work ‘holder for securing uniform dis
tribution of the evaporated material. means for
driving the said rotatable means, and means for
rotating the work holder.
each of the evaporating means selectively into
axial alignment with the work holder, means for
selectively actuating the evaporating means thus
aligned, rotatable means between the evaporating
8. In a vacuum coating apparatus a work 5 means and the work holder for securing uniform
holder, a plurality of evaporating means mounted
distribution of the evaporated material, motor
on a carrier, means for shifting the carrier from
driven means for driving the said rotatable means.
and magnetic means for rotating the work holder.
the exterior of the apparatus to shift each of
the evaporating means selectively into axial align
12. In a vacuum coating apparatus a work
ment with the work holder. means for selectively 10 holder. a plurality of evaporating means mounted
actuating the evaporating means thus aligned, ro
on a carrier, magnetic means for shifting the car
tatable means between the evaporating means and
rier from the exterior of the apparatus to shift
the work holder for securing uniform distribution
each of the evaporating means selectively into
of the evaporated material, motor driven means
axial alignment with the work holder, means for
for driving the said rotatable means, and means
selectively actuating the evaporating means thus
for rotating the work holder.
aligned, rotatable means between the evaporating
9. In a vacuum coating apparatus a work
means and the work holder for securing uniform
holder. a plurality of evaporating means mounted
distribution of the evaporated material, motor
on a carrier, means for shifting the carrier from
driven magnetic means for driving the said rotat
the exterior of the apparatus to shift each of 20 able means. and magnetic means for rotating the
the evaporating means selectively into axial align
work holder whereby a plurality of coats of dif
ment with the work holder, means for selectively
ferent material may be applied to the work carried
actuating the evaporating means thus aligned,
on said work holder without breaking the vac
uum in said apparatus.
rotatable means between the evaporating means
and the work holder for securing uniform dis 25
13. In apparatus for the deposition of evap
tribution of the evaporated material, motor driven
orated material upon a circular portion of a work
means for driving the said rotatable means, and
surface, the combination of an evaporator, a work
magnetic means for rotating the work holder.
holder in opposed relation thereto, and a rotatable
10. In a vacuum coating apparatus a work
attenuator in the form of a blade for securing a
holder, a plurality of evaporating means mounted 30 distribution of said material over said surface.
on a carrier. means for shifting the carrier from
means for rotating said blade, said blade being in
the exterior of the apparatus to shift each of the
evaporating means selectively into axial align
terposed between said holder and said evaporator
and rotatable about the axis of transmission of
ment with the work holder, means for selectively
said material to said work surface, the ratio of
actuating the evaporating means thus aligned. ro 35 the radius of the circular path de?ned by the point
tatable means between the evaporating means
of said blade farthest from said axis of trans
and the work holder for securing uniform dis
mission, to the radius of said work surface, being
trlbution of the evaporated material. motor driven
in direct proportion to the ratio of the distance
magnetic means for driving the said rotatable
between evaporator and blade to the distance
means, and magnetic means for rotating the work 40 between evaporator and work surface.
holder.
14. The apparatus of claim 13 in which said
11. In a vacuum coating apparatus a work
blade is substantially elliptical in shape and in
holder, a plurality of evaporating means mounted
which said blade has an end in register with said
on a carrier, magnetic means for shifting the car
axis of transmission.
rier from the exterior of the apparatus to shift 45
GLENN LESLIE DDMIMICK.
Certi?cate of Correction
Patent No. 2,410,720.
November 5, 1946.
GLENN LESLIE DIMMICK
- It is hereby certi?ed that errors appear in theCprinted speci?cation of the above
numbered patent requiring correction as follows: olumn 5, line 65, for “or” before
“converted” read are; column 6, line 70, claim 7, for the word “or” before “shifting”
read for; and that the said Letters Patent should be read_ with these corrections
therein that the same may conform to the record of the case in the Patent O?ice.
Signed and sealed this 28th day of January, A. D. 1947.
[am-1
LESLIE FRAZER,
First Assistant ?ommissioner of Patents.
2,410,120
7
and the work ‘holder for securing uniform dis
tribution of the evaporated material. means for
driving the said rotatable means, and means for
rotating the work holder.
each of the evaporating means selectively into
axial alignment with the work holder, means for
selectively actuating the evaporating means thus
aligned, rotatable means between the evaporating
8. In a vacuum coating apparatus a work 5 means and the work holder for securing uniform
holder, a plurality of evaporating means mounted
distribution of the evaporated material, motor
on a carrier, means for shifting the carrier from
driven means for driving the said rotatable means.
and magnetic means for rotating the work holder.
the exterior of the apparatus to shift each of
the evaporating means selectively into axial align
12. In a vacuum coating apparatus a work
ment with the work holder. means for selectively 10 holder. a plurality of evaporating means mounted
actuating the evaporating means thus aligned, ro
on a carrier, magnetic means for shifting the car
tatable means between the evaporating means and
rier from the exterior of the apparatus to shift
the work holder for securing uniform distribution
each of the evaporating means selectively into
of the evaporated material, motor driven means
axial alignment with the work holder, means for
for driving the said rotatable means, and means
selectively actuating the evaporating means thus
for rotating the work holder.
aligned, rotatable means between the evaporating
9. In a vacuum coating apparatus a work
means and the work holder for securing uniform
holder. a plurality of evaporating means mounted
distribution of the evaporated material, motor
on a carrier, means for shifting the carrier from
driven magnetic means for driving the said rotat
the exterior of the apparatus to shift each of 20 able means. and magnetic means for rotating the
the evaporating means selectively into axial align
work holder whereby a plurality of coats of dif
ment with the work holder, means for selectively
ferent material may be applied to the work carried
actuating the evaporating means thus aligned,
on said work holder without breaking the vac
uum in said apparatus.
rotatable means between the evaporating means
and the work holder for securing uniform dis 25
13. In apparatus for the deposition of evap
tribution of the evaporated material, motor driven
orated material upon a circular portion of a work
means for driving the said rotatable means, and
surface, the combination of an evaporator, a work
magnetic means for rotating the work holder.
holder in opposed relation thereto, and a rotatable
10. In a vacuum coating apparatus a work
attenuator in the form of a blade for securing a
holder, a plurality of evaporating means mounted 30 distribution of said material over said surface.
on a carrier. means for shifting the carrier from
means for rotating said blade, said blade being in
the exterior of the apparatus to shift each of the
evaporating means selectively into axial align
terposed between said holder and said evaporator
and rotatable about the axis of transmission of
ment with the work holder, means for selectively
said material to said work surface, the ratio of
actuating the evaporating means thus aligned. ro 35 the radius of the circular path de?ned by the point
tatable means between the evaporating means
of said blade farthest from said axis of trans
and the work holder for securing uniform dis
mission, to the radius of said work surface, being
trlbution of the evaporated material. motor driven
in direct proportion to the ratio of the distance
magnetic means for driving the said rotatable
between evaporator and blade to the distance
means, and magnetic means for rotating the work 40 between evaporator and work surface.
holder.
14. The apparatus of claim 13 in which said
11. In a vacuum coating apparatus a work
blade is substantially elliptical in shape and in
holder, a plurality of evaporating means mounted
which said blade has an end in register with said
on a carrier, magnetic means for shifting the car
axis of transmission.
rier from the exterior of the apparatus to shift 45
GLENN LESLIE DDMIMICK.
Certi?cate of Correction
Patent No. 2,410,720.
November 5, 1946.
GLENN LESLIE DIMMICK
- It is hereby certi?ed that errors appear in theCprinted speci?cation of the above
numbered patent requiring correction as follows: olumn 5, line 65, for “or” before
“converted” read are; column 6, line 70, claim 7, for the word “or” before “shifting”
read for; and that the said Letters Patent should be read_ with these corrections
therein that the same may conform to the record of the case in the Patent O?ice.
Signed and sealed this 28th day of January, A. D. 1947.
[am-1
LESLIE FRAZER,
First Assistant ?ommissioner of Patents.
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