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Патент USA US3100719

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Aug. 13, 1963
H. BRESMER ETAL
3,100,714
OPTICAL CROWN GLASSES
Filed Oct. 3, 1961
Q"
I
I
I
I
I
I
.
10 2a a0 41’; 56 60 76 80 90 8/02
_
B)’
INVENTORS
W: M
ZWM
%
ice
States Patent
3,100,714
Patented Aug. 13, 1963
2
1
alkaline earth oxides can be substituted partially within
the given limits by the following oxides, whereby, how
3,160,714
OPTICAL CROWN GLASSES
Heinz Briimer and Norbert Meinert, Wetzlar (Lahn), Ger
many, assignors to Ernst Leitz, G.rn.b.H., Wetzlar
ever, the given limits for the calcium- and barium-oxide
portions remain constant:
Percent by weight
(Lahn), Germany
ZnO and/or CdO ______________________ __ 0 to 15.0
A1203 _______________________________ __ 0 to 10.0
La2O3 ________________________________ .__ 0 to 7.0
Filed Oct. 3, 1951, Ser. No. 142,551
Claims priority, application Germany Nov. 5, 1960
7 Claims. (Cl. 106-54)
Our invention relates to optical glasses which lie in the 10
range of strong to strongest crown glasses.
ZrO2
___
_
0 to 16.0
PbO ________________________________ __ 0 to 7.5
Tloz
__-_
.._...._
..._ 0 to
7.5
TaaOs and/or N'bgoa ___________________ __ 0 to 7.5
Recently the application of lanthanum crown glasses
W03 _
____
_
__ 0 to
7.5
for objectives of high value has attained increasing im
portance, yet in the preparation of normal objectives re
The sum of the substitute oxides can amount to 32.5% by
cently, as formerly, strong and strongest crown glasses 15 weight.
~
'
have been used predominantly. These two types of
It is appropriate to add the phosphoric oxide entirely
glasses were, until the present time, melted down on a
or at least in part in the form of boron phosphate, meta—,
pyro- and ortho-phosphates of the alkaline earths as well
silicate base with partial substitution of boric oxide and
very high proportions of alkaline earth metals, principally
barium oxide. The majority of these glasses is strongly
sensitive to spotting and, in fabrication, produce a high
quota of rejects.
Most recently the tendency is to use phosphoric oxide
as of zinc and/ or cadmium.
In Table 1 are examples of compositions of strong
crown glasses according to the invention in percent by
weight.
Table 1
as a base glass with the addition of boric oxide. The
glasses thus melted down are essentially resistant to chemi 25
cal attack and spotting but have the disadvantage that they
incline very easily in commercial production to crystalli
zation. In some types the production of pressings and
“gob” by this means is not possible.
By means of systematic stabilizing reasearch it has been
Melt No ................... __
A/Br 1
A/Br 8
10. 0
15. 0
10. 0
17. 0
15.0
15. 0
GIN/A9
.-
found that all of these obstacles can be obviated if one
selects as a glass base a ternary combination consisting
of silica, bon'c oxide and phosphoric oxide. In this for
l8. 9
23. 5
4. 0
7. 0
4. 6
7.0
4. 6
l. 6352
55.4
mation of a glass base one uses, besides other oxides,
larger amounts of oxides of the alkaline earth metals with
the exception of beryllium and radium and obtains glasses
‘
10. 9
27. 5
10. 0
Melt No ________________________ __
GIN/Br 1
11.2
17.0
10. O
15.1
16.8
14. 9
10. 0
3.0
12.9
27. 5
4. 6
9. 2
29. 5
13. 7
........ __
........ __
1. 6291
56. 6
1.6 "8
58. 7
GIN/A11
O/N/AIZ
11.5
18. 5
17. 0
10. 0
11.5
18. 5
17.0
10. 0
5. 0
4. 6
1.6408
54. 8
C/N/A13
which are essentially more stable than the original silicate
glasses and which do not exhibit the tendency to crystalla
tion of the phosphate glasses.
‘
The glasses of the above invention have as a glass form
ing base a combination of silica, boric oxide and phos
phoric oxide within the following limits:
_
_
5.5 to 20.0
B203
10.0 to 31.5
5.0
27. 5
corner points of the hatched ?eld have the following
10. 0
15. 1
14.9
values.
55
9. 9
15.0
14. 7
weight.
For the determination of special optical values, the
5. 5
17. 0
22. 5
2%
18. 9
13. 5
12. 9
23. 5
36. 2
27. 5
13.7
4.0
5.0
2.0
4. 6
1. 6-119
55.0
_________ _.
6. 7
5.0
4. 6
1. 6538
55. 5
4.0
1. 6359
56. 8
E/Br 10
17.7
14. 9
4. 6
7.1
36. 2
5. 0
2. 5
1. 6229
60.0
5.0
2.0
_-_______-
12.0
The amount of calcium oxide should be at least 5% by
weight, the amount of barium oxide at least 20% by
B/Br 14
20. 0
Melt No ________________________________ ._
earth metals, magnesium, calcium, strontium and barium.
1. 6460
56. 0
3/131‘ 4
10. 0
17.0
15.0
________ ._
The total content of the glasses consists of the above
mentioned glass formers and the oxides of the alkaline
-_..--_____-_
1. 6182
59. 7
Melt No __________________ __ GIN/Br 2 A/Br 17
be between 35 and 47% by weight of the ?nished glass.
In the accompanying diagram the claimed ?eld of the 50
ternary combination, SiO2—B2O3--P2O5, extended to
100% by Weight of these three ingredients is shown. The
P2052340
P2O5=21.3
5.0
7. 5
50. 8
45
At the same time the sum of the three ingredients is to
‘B2O3=54.3
B2O3=67.0
‘
2.5
1. 6199
60. 2
P205 ______________________________ __ 10.0 to 16.0
(1) SiO2=11.7‘
(2) SiO2=11.7
8.0
5.0
27. 5
__________ _-
Percent by weight
SiOg ____
10.5
10. 0
10. 0
15.0
2. 5
_-_______
7. 6
1. 6389
56. 2
E/Br 11
12.0
17.7
14. 9
............ .
9. 2
36. 2
5.0
3. 5
1. 5
1. 6184
59.1
3,100,714
3
41
In Table 2 are shown two examples in which the phos
1400" C. The melt is stirred as in the usual manner for
phoric oxide is substituted as metaphosphate.
homogenizing.
'
1The pouring temperature can be. so chosen that the
Table 2
necessary viscosity for the particular casting method has
been reached. It can be cast equally well according to
the old method or according to modern belt casting
methods. The transformation zone of the glasses lies, al
Ways according to the composition, between about 550°
MeltNo ________________________________ “I A/Br12 l A/Br13
10.0
120
22.0
19.1
5710
2&3
24:0
The following Table 4 shows the chemical stability of
each of two glasses of the same optical position. In it
$3
1: 6298
£6344
are A1 and A2 usual glasses of comerce while B1 and B2
are glasses according to the above invention. The tests
13.0
-
13.9
10
56- 5
5
and 600 c
55- 4
were carried through according to H. Bredow, Glas-Email
Keramo-Technik 10 (1959), vol. 8, pages 297-299.
Table 4
A1
131(0/N/A5)
551.6413.
I
I
m=1.64l4.
A2
n..=1.6229.
B2 (E/Br10)
m=1.6220.
v.=55.24
6.:5435.
v..'=60.1
v.=60 0
11/10 HNOs, 329.0 mg.
Standard acetate, 254.0 mg.
11/10 HNOz, 104 mg.
Standard acetate, 114.0.
11/10 HNOa, 397 mg.
Standard acetate, 203.0 mg.
n/10 HNOz, 100 mg.
Standard acetate, 74 mg.
SiOz, 30.0% by weight.
13203, 15.0% ,by weight.
BaO, 48.0% by weight.
NazO____
A1gO3__._
7.0% by weight.
S101, 10.0% by weight.
B201, 15.1% by weight.
BPOi, 14.9% by weight.
0210, 9.2% by Weight.
13:10, 27.5% by weight.
ZnO, 13.7% by weight.
ZnO_____
A1203, 5.0% by Weight. I
T101 .___
ZrO;, 4.6% by weight.
S104, 30.0% by weight.
13:03, 18.8% by weight.
251% } 2.0% by weight.
13:10, 47.6% by weight.
A1201, 1.6% by weight.
A1201, 2.5% by ewight. .
Table 3 contains a’ collocation of melts whose optical
Having described our invention, we claim:
1. Optical glass having an index of refraction 716 above
1.61 and an Abbe number ve above 48.2 and consisting
values lie in the region of the strongest crown glasses.
Table 3
Melt N0 ___________________ __ GIN/A7
40 essentially of, (1) 35 to 47 percent by weight of silica,
A/Br 14
11/131 15
10. 0
10. 0
17. 0
' 17. 0
17. 0
17. 0
16. 3
12.9
27. 5
3. 0
15. 0
18.9
23. 5
4. 0
15. 0
13. 0
23. 5
4. 0
16. 0
13. 9
23. 5
4.0
7. 0
boric oxide and phosphoric oxide of which the silica con
tent lies ‘between 5.5 and 20 percent by weight, the boric
A/Br 16
11. 2
________ __
$10,, 12.0% by weight.
B101, 17.7% by weight.
BPO4, 14.9% by weight.
OaO, 4.6% by welght.
13610, 36.2% by weight.
SrO, 7.1% by weight.
ZnO, 6.0% by weight.
10. 0
____________________________ __
2. 0
2. 0
2. 0
4. 6
4.6
4. 6
5. 0
oxide between 10.0 and 31.5 percent ‘by weight and the
phosphoric oxide between 10 and 16 percent by weight
45 and (2) the balance of 65 to 53 percent consists essentially
of oxides selected from the group consisting of magnesium
oxide, calcium oxide, strontium oxide and barium oxide
of which balance calcium oxide is present in amount
equal to at least 5 percent by weight of the‘ glass composi
tion and barium oxide is present in amount equal to at
6. 0
5. 0
1. 6500
' 54. 3
1. 6637
64. 4
least 20 percent by weight of the glass composition.
________ -_
'2. Optical glass according to claim 1 in which the
1. 6737
4s. 2
oxide (2) is substituted up to an amount of 32.5 percent
by weight by the following oxides within the above stated
D/Br 5
14. 0
7. 0
15. 0
7. 7
27. 5
13. 7
6. 0
5. 0
4. 6
1. 6576
49. 0
D/Br 7
12.6
s. 5
15. 0
6. 0
27. 5
13. 7
4. 0
9. 2
4.6
1. 6414
51. 7
D/Br 3
12. 5
3.0
15. 0
0. 2
27.6
13. 7
4. 5
5. 0
4. 6
1. 6588
50. s
55
V For the melting down of colorless optical glasses ac
are intimately mixed and the mix is melted in a crucible.
1
Percent by weight
ZnO and/or CdO ____ _‘__'_ ______________ __ 0 to 15.0
A1203 _______________________________ .._ 0 to 10.0
La2O3
_______________________________ ._.
60 ZrOz ________________________________ __ 0 to 16.0
PbO
65
cording to the invention raw materials of high purity grade
limits:
________ __.. _____________________ _.. 0 to‘
7.5
T102 ________________________________ -_ 0 to
7.5
T3205 and/Or Nb205 _______________ -l--_-- 0 to
7.5
W03 ________________________________ __ 0 to
7.5
3. Optical glass according to claim 1 in which the
phosphoric oxide is introduced into the composition at
least in part in the form of boron phosphate.
’
4. Optical glass according to ‘claim 1 in which the
‘_ According to the invention there can be added to the 70 phosphoric oxide is introduced into the composition at
glasses in the customary manner small portions for de
least in part in the form of a phosphate of an alkaline
colorizer, for example, arsenic oxide or antimony oxide.
earth metal.
7
Platinum is to be used as a crucible material although
5. Optical glass according to claim 2 in which the phos
crucibles of otherwise usable materials can also be used.
phoric oxide is introduced into'the composition at least
The melting temperature lies between 1300° C. and 75 in part in the form of a phosphate of zinc.
3,100,714
r
5
6. Optical glass according to claim 2 in which the
a
phosphoric oxide is introduced into the composition at
least in part in the form of a phosphate of cadmium.
7. Optical glass according to claim 1 in which an oxide
of the group consisting of arsenic oxide and antimony
oxide is introduced into the composition.
5
6
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,532,386
2,615,817
$009,819
,
'Armlstead ------------- -- Dec- 5’ 1950
stanworth ----------- -- Oct‘ 28: 1952'
Ge?cken et a1 --------- -- NOV' 21, 1961
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