U.S. patent number 3,689,134 [Application Number 05/036,290] was granted by the patent office on 1972-09-05 for two-partite optical components with air space.
Invention is credited to DE, Franz John Saller, Thuisstrasse 2, Franz X. Leitmeir, Winterstrasse 2.
United States Patent |
3,689,134 |
|
September 5, 1972 |
TWO-PARTITE OPTICAL COMPONENTS WITH AIR SPACE
Abstract
A multiple lens combination with an air space in which at least
three similar spacer bodies of the type which are commercially
available in large quantities with relatively small tolerances,
such as steel balls, are held in abutment against an internal bore
of the lens mounting by a cage ring whereby the quotient of the
permissive tolerance of the air space between the mutually facing
lens surfaces and the diameter tolerance of the internal bore is at
least approximately equal to the tangent of the wedge angle of the
air space at its edge.
Inventors: |
Franz X. Leitmeir, Winterstrasse
2 (8031 Maisach-Munich), DE (N/A), Franz John Saller,
Thuisstrasse 2 (Neuaubing B. Munich), DE (N/A) |
Family
ID: |
5733889 |
Appl.
No.: |
05/036,290 |
Filed: |
May 11, 1970 |
Foreign Application Priority Data
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May 10, 1969 [DE] |
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19 24 017.6 |
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Current U.S.
Class: |
359/830 |
Current CPC
Class: |
G02B
7/021 (20130101) |
Current International
Class: |
G02B
7/02 (20060101); G02b 007/02 () |
Field of
Search: |
;350/54,96,252-257,299,178 ;308/189A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: John K. Corbin
Assistant Examiner: Michael J. Tokar
Attorney, Agent or Firm: Craig, Antonelli and Hill
Claims
We claim:
1. The combination of a lens mounting and of a two-partite optical
component with an air space therebetween mounted within the lens
mounting, characterized in that at least three similar spacer
members in the form of balls which are adapted to be made in large
quantities with relatively narrow tolerances serve for defining the
air space and are held abuttingly against a bore of the lens
mounting by a cage ring means and in abutment with the mutually
facing lens surfaces of the two-partite optical component, and in
that the quotient of the permissive tolerance of the air space
between the mutually facing lens surfaces and the diameter
tolerance of the bore are at least approximately equal to the
tangent of the wedge angle of the air space at its edge formed by
the curvature of the spaced mutually facing lens surfaces.
2. The combination according to claim 1, characterized in that said
spacer members are steel balls.
3. The combination according to claim 1, characterized in that the
abutment force, by means of which the spacer members are pressed
radially against the internal bore, is larger than the force
component effective in the radial direction which results from the
force exerted in the axial direction on the lenses by elastic
intermediate means and from the angular position of the surface
areas of the lenses in contact with the spacer members.
4. The combination according to claim 1, characterized in that
steel balls having substantially the same diameter within small
tolerances, which are used as spacer members, form an essentially
gapless ring.
5. The combination according to claim 3, characterized in that an
intermediate rigid ring secured against rotation is disposed
between the elastic intermediate means and the securing means.
6. The combination according to claim 5, characterized in that the
axial pressure is produced by at least three axial, threaded
elements which press the intermediate ring with predetermined force
against the elastic intermediate means.
7. The combination according to claim 3, characterized in that an
elastic element of large surface friction is provided between an
outer lens surface and the mounting.
8. The combination according to claim 7, characterized in that a
plug is provided near the edge of a lens.
9. The combination according to claim 8, characterized in that said
plug has a high inherent friction.
10. The combination according to claim 8, characterized in that
said plug has a high adhesive force.
11. The combination according to claim 7, characterized by seal
means for sealing the air space between the lenses against the
outside.
12. The combination according to claim 7, characterized in that
said seal means include elastic rings.
13. The combination according to claim 1, characterized in that
said quotient is larger than said tangent.
14. The combination according to claim 1, characterized by securing
means retaining the lenses in the mounting, and intermediate means
between the lenses and said securing means.
15. The combination according to claim 14, characterized in that an
intermediate rigid ring secured against rotation is disposed
between the elastic intermediate means and the securing means.
16. The combination according to claim 14, characterized in that
the axial pressure is produced by at least three axial, threaded
elements which press an intermediate ring with predetermined force
against the elastic intermediate means.
17. The combination according to claim 1, characterized in that an
elastic element of large surface friction is provided between an
outer lens surface and the mounting.
18. The combination according to claim 1, characterized in that a
plug is provided near the edge of a lens.
19. The combination according to claim 18, characterized in that
said plug has a high inherent friction.
20. The combination according to claim 18, characterized in that
said plug has a high adhesive force.
21. The combination according to claim 1, characterized by seal
means for sealing the air space between the lenses against the
outside.
22. The combination according to claim 21, characterized in that
said seal means include elastic rings.
23. The combination of a lens mounting and a multiple lens optical
system of spaced lenses arranged in said lens mounting,
characterized in that at least three similar spacer members adapted
to be made in large quantities with relatively narrow tolerances
are held in contact with mutually facing refractive surfaces of the
lenses and abuttingly against a bore of the lens mounting by a cage
ring means such that the lenses are maintained a fixed axial
distance apart.
24. The combination according to claim 23, wherein the spacer
members are balls.
Description
The present invention relates to multiple lens combinations, and
more particularly to multiple lens combinations having an air space
between components thereof.
The present invention is concerned with the task to be able to
maintain in objectives composed of several lenses, the air space
between two lenses or components within smallest possible
tolerances also in case of manufacture of large series. It is known
in connection therewith to insert intermediate rings between the
lenses placed loosely into the mounting or barrel; if the air space
has to be kept within narrow tolerances, then the rings have to be
machined correspondingly accurately whence they are then very
costly. The same is true in case that the lenses are mounted in
rings which abut against one another with one surface each and thus
have to be matched very accurately at these surfaces.
In contradistinction thereto, the present invention proposes to
determine the air space between two lenses or components by spacer
bodies which are available in very large numbers and generally with
very high dimensional accuracies. Thus, it is known for many
decades in connection with telescope achromats of the two-component
lens type, to determine the very narrow air space between the two
lenses by a tin-foil ring or also by only three small tin-foil
pieces which are mounted equidistant along the edge. The objective
designer calculates from the predetermined axial length of the air
space and from the curvatures of the abutting surfaces, the air
space thickness at the lens edge, tin-foil of this thickness can be
selected by relatively simple thickness measurements that can be
carried out accurately. More appropriate is the reverse method
followed for quite some time which consists of selecting a
commercial value or size for the edge thickness of the air space
and the thickness of the tin-foil or of another intermediate layer
corresponding thereof, of calculating from the abutting radii of
the surfaces the axial length of the air space and of matching
thereto the correction of the system. This method is also
applicable to the subject matter of the present invention.
The present invention modifies the described method especially in
the direction of larger air space lengths, in that it utilizes as
spacer bodies for the determination of the air space lengths,
mechanical measuring or standardized parts, for example, steel
balls inserted between the surfaces. Such balls are, as is known,
commercial items available everywhere and at all times with very
small tolerances in the diameter thereof. In the same manner as
described above, the diameter of the steel balls is, for the most
part, predetermined, and the calculation is matched thereto; more
rarely is it appropriate to determine the required diameter from
the given air space thickness.
In order to secure three balls which--as is known--define an
unequivocal position of the mutually facing lens surfaces,
equidistantly at the edge, it is necessary to keep the recess or
bore of the mounting in those places, where the balls abut thereat
according to the present invention, within tolerances in accordance
with the differences in radii of curvature of the two abutting
glass surfaces. The quotient of the possible tolerance of the air
space, on the one hand, and of the tolerance of the diameter of the
bore, on the other, is thereby equal or larger than the tangent of
the wedge-angle of the air space at its edge. If, for example, the
air space is formed by concentric surfaces, i.e., has the same
thickness along the axis as at the edge, as measured
perpendicularly to the surfaces, then the bore of the mounting may
be kept within very large tolerances at this place because a
displacement of the balls in the radial direction does not
influence at all the air space.
However, the more the shape of the air space approaches a
converging or dispersing lens, the more the bore for the abutment
of the balls has to be kept within small tolerances, i.e., the
smaller the tolerance for the bore. If the air space has the shape
of a dispersing lens, then a force exists seeking to press the
balls toward the outside, and the balls abut without further
measures at the bore of the mounting; by the use of a conventional
cage ring which may be force-locking, though not decisive from any
point of view, it is easy to assure the same spacing and a
spatially unchanged position of the balls.
If, however, the air space has the shape of a converging or
focusing lens, then there results a force seeking to press the
balls toward the inside which has to be absorbed by the cage
ring.
The cage ring presses the balls outwardly, even when self-locking
exists due to friction. For this purpose, the cage ring is made
according to the present invention from elastic material, for
example, of synthetic resinous material of any known type, and is
so dimensioned that a pre-stress exists at all times which presses
the balls outwardly with sufficient force.
If, however, the air space should be wedge-shaped so strongly at
the place of the balls that no self-locking occurs any longer as a
result of friction, i.e., if the axial pressure holding together
the lenses in the mounting endeavors by means of a component to
displace the balls inwardly, then the force supplied by the cage
ring has to be chosen carefully and must be clearly larger in order
to prevent the same with certainty. It is then appropriate to
construct the cage ring rigidly.
The axial lens pressure in the mounting and the radial pressure
exerted by the cage ring on the balls thus must be able to be
appropriately matched to each other. Consequently, it is part of
the present invention that the lenses are held axially in the
mounting or barrel by the interposition of an elastic member, for
example, of a rubber ring. This ring is appropriately an
intermediate layer or spacer between a lens and a securing member,
for example, a threaded or bayonet ring, mounted in the normal
manner.
During the tightening of such a ring there exists the danger that a
tangentially effective force is exerted on the elastic intermediate
layer and therewith on the lens adjacent thereto, which has as a
consequence a rotation of the entire arrangement, or at least of
one lens thereof. This, however, leads to mutual proportioning of
the radial and axial forces that is not completely satisfactory. It
is therefore additionally proposed according to the present
invention to insert a rigid intermediate or spacer ring between the
securing member and the elastic intermediate layer which rigid
intermediate ring is secured against rotation by conventional
means. The axially effective pressure is then produced by a means
determining the same, for example, by means of three screws
extending in the axial direction through the securing element which
are tightened with a measurable force and abut against the
intermediate ring.
It can be readily seen that the axial pressure which is transmitted
from the lens surfaces to the three balls, for the most part
comparatively small in diameter, involves only very small surfaces
of the lenses so that elastic indentations in the glass and
therewith reductions of the air space lengths exceeding the
permitted tolerances occur already at very slight axial pressures
which do not assure a position of the lenses secure against
rotation.
Consequently, it is part of the present invention to utilize more
than three balls for the definition of the air space which is
appropriate when the permissive tolerance of the air space is
clearly larger than the diameter tolerance of the balls. With a
very small axial pressure, the two mutually facing lens surfaces
initially abut or rest on three balls. If the pressure is
increased, then flat impressions or indentations in the lens
surfaces result from these three balls, however, further balls
assume little by little portions of the increasing pressure force
until finally all of the balls more or less carry out a support
function whereby the deepest elastic indentation in one of the lens
surfaces is approximately equal to the tolerance range of the ball
diameter. It has been found that this amount in practice does not
lead by a long shot to the destruction of the lens surface.
Instead of securing the rigid intermediate ring located between the
elastic intermediate layer and the securing member against axial
rotation, this locking action can be realized also directly at the
lenses. It is part of the present invention to insert into the
mounting, appropriately at the outer surfaces of the lenses, an
elastic member with strong surface friction, for example, a soft
rubber ring which is only slightly deformed by the lens; the
correct position of the lens continues to be determined, as before,
by its abutment at a rigid mounting part.
Instead of such a ring, there may also be provided in a mounting
portion a bore disposed parallel to the axis, which meets in one
place at least the mounting support of the cylindrical lens edge,
if possible, however, also the axial support of a lens surface.
After the assembly of all lenses and mounting parts, this opening,
appropriately a dead-end bore, is filled with an adhesive and
curable material so that the lens is connected into one piece with
the mounting, at least to the extent that the rotation is
prevented. In order to avoid a corrosion of the spacer bodies, the
optical components may be closed off in a tight manner on both
sides by elastic rings.
These and further objects, features, and advantages of the present
invention will become more obvious from the following description
when taken in connection with the accompanying drawing which shows,
for purposes of illustration only, several embodiments in
accordance with the present invention, and wherein:
FIG. 1 is a partial axial cross-sectional view through a first
embodiment of a multi-lens combination with an air space in
accordance with the present invention;
FIG. 2 is a partial transverse cross-sectional view, at right angle
to the axis of the multiple lens combination, through a cage ring
in accordance with the present invention;
FIG. 3 is a partial axial cross-sectional view through a second
embodiment of a multiple lens combination with an air space in
accordance with the present invention; and
FIGS. 4, 5, and 6 are partial cross-sectional views through still
further modified embodiments of multiple lens combinations with an
air space in accordance with the present invention.
Referring now to the drawing wherein like reference numerals are
used throughout the various views to designate like parts, and more
particular to FIG. 1, reference numeral 1 designates in this figure
a converging or focusing lens and reference numeral 2 a dispersing
lens which are held inside a conventional mounting 3; both lenses 1
and 2 are secured by the elastic intermediate layer 4, for example,
in the form of a rubber ring, and by a locking ring 5.
Appropriately, a stepped cut 6 is provided for that purpose at the
lens 2. Reference numeral 7 designates a conventional lacquer
protection which forms no part of the present invention and which,
adhesively applied, secures the various parts against mutual
rotation after drying or curing of the lacquer.
Three steel balls 12 of identical diameter and placed along the
edge between the lenses 1 and 2 serve for the definition of the air
space between the two lenses; the steel balls 12 are held
equidistant, on the one hand, by the cage ring 13 made of
conventional synthetic resinous material and are pressed, on the
other, by the cage ring 13 against the internal bore 14 of the
mounting 3, whose diameter tolerance may be the larger the more
parallel the mutually facing surfaces of the lenses 1 and 2.
A part of the cage ring 13 is shown in FIG. 2 in a transverse cross
section as viewed in the axial direction; each of the three steel
balls 12 is pressed outwardly by a web 15 of the ring 13.
FIG. 3 illustrates a mounting 3 with more than three balls 12 and a
rigid cage ring 13; the lens 1 is secured against axial rotation by
the soft rubber ring 16.
In FIG. 4, a subsequently injected and cured synthetic resinous
material plug 17 in a bore of the mounting 3 secures the lens 1
against rotation.
In both FIGS. 3 and 4, reference numeral 18 designates a rigid
intermediate ring secured against rotation.
In FIG. 5, the rigid ring 4 is pressed against the lens 2 with
predetermined measurable force by the use of several screws 19
distributed over the circumference; the screws 19 are supported in
the securing element 5 which is in the form of a threaded ring.
FIG. 6 finally illustrates a sealing ring 20, for example, made
from silicon rubber which in conjunction with the soft rubber ring
16 seals off the air space between the lenses 1 and 2 and therewith
the space between the same against the outside.
While we have shown and described several embodiments in accordance
with the present invention, it is understood that the same is not
limited thereto but is susceptible of numerous changes and
modifications as known to those skilled in the art, and we
therefore do not wish to be limited to the details shown and
described herein but intend to cover all such changes and
modifications as are encompassed by the scope of the appended
claims.
* * * * *