Note: Descriptions are shown in the official language in which they were submitted.
CO~OR IMAGE INTENSJFI~R
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B~CK R_UND OF THE INVENTION
Field of the Invention:
This invention relates to image intensifiers with
particular reference to fiber optic means and method
for providing a full color image intensification system.
Discussion of the Prior Art
Image intensifiers capable of a high degree of
image intensification have been developed for night
vision and similar low light level applications but
provide only monochromatic images (e.g. green-black as
from a P 20 phosphor).
The system disclosed in U. S~ Patents Nos. 3,141,].05;
3,321~658 and 3,436,142 are exemplary.
~~ In photographic view-finding systems, surveillance
devices, medical instruments and other apparatuses
where color rendition i5 essent:ial, the advantages of
image intensification have heretofor been denied.
~ Accordingly, it is an object of the present invention
to provide for full color image output in image intensifier
devices: and
~nother object is to provide a composite full
color image output of high resolution with still higher
resolution of image detail in each monochromatic component
of the image.
Other objects and advantages of the lnvention will
become readily apparent from the fo]lowing description.
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107
S~ ~RY OE` THE INVENTION
The aforesaid and corollary objectives of the
invention are accomplished by providing intensified
full color images with a fiber optic color ~ilter array
~hich separates "white" light into three primary color
components at the input of an intensifier. A similar
color filter at the output of the intensifier affords
the full color displa-y. The input and output filters
I are identically geometrically patterned for minimizing
¦ distortion. Multi-colored phosphor within the intensifier
may be substituted for the output filter.
The filter is formed of juxtapositioned colored
fibers (the primary colors) each subdivided into a multiplicity
of smaller elemental fibers (e.g. as a multifiber) to provide
increased resolution of image detail within each color area.
Details of the invention will become more readily
apparent from the ollowing descriptiQn when taken in
co~:junction with the accompanyinq drawings.
IN THE DRAWINGS
Fig. 1 is an illustration in cross-section of a preferred
embodiment of the invention;
Fig. 2 is a greatly enlarged face view of a cluster of
colored multifiber light filtering components, the con-
figuration of which is useful in fabricating the color filter
plates of the imaqe intensifier illustrated in Fig. l;
Eig. -- is a lragmentary elevati(~ l view of a
filter plate formed of lnterfitted clusters of colored
multifibers of the type illustrated in Fig. 2;
Fig~ 4 is a cross-sectional view of a modification
of the invention;
Fig. 5 is another modification of the invention
shown in cross-section; and
Fig. 6 is a diagrammatic illustration, in perspective,
of a fiberscope system in which an emhodiment of the
invention is incorporated for output image intensification ~¦
and color display.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to Fig. 1 of the
drawings, image intensifier 10, being of the proximity
focused type, comprises a pair of spaced image-receiving
and image-emitting faceplates 12 and 14 respectively
~ithin envelope 16 which provides an evacuated space 18
for image energy conversion from light-to-electron~
eiergy and back to intensified light for final display.
Face 20 of plate 12 is provided wlth photocathode ~2
and face 24 of plate 14 is provided with light-emitting
phosphor coating 26r High electricai voltage is provided
across space 18 by DC source 28.
To the extent thus far described, intensifier 10
having faceplates 12 and 14 each constructed of a great
multiplicity of fused optical fi~ers 12a and 14a is of
conventlonal design requiring no further description.
:~12~
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,
Those int~sted in details of image intensifiers o~
this tvpe may, however, refer to U. S. Patents Nos.
3,141,105; 3,321,658; and 3,436,142.
In making intensifier 10 adaptable to producing
intensified full color renditions of colored images
directed thereinto, additional fiber optic faceplates
30 and 32 are provided, preferably but not necessarily,
within envelope 16.
Plates 30 and 32, being of identical geometrical
patterning and carefully identically aligned along axis
34 of intensifier 10, are each formed of a great number
of tightly interfitted and preferably fused, cemented
or otherwise connected together multifibers 36 (Figs.
1, 2 and 3)~ iDe. each multifiber 36 consists of a
multiplicity of individual tightly juxtapositioned
light-conducting fibers 38 (Fiy. 2~.
Multifibers 36 are preferably assenbled in cluste~s
of three as illustrated by the triangular T-formation
of Fig. 2.
In each triangular cluster of multifibers 36,
there is provided one multifiber 3~ formed of colored
fibers 38 adapted to transmit substantially only one of
the primary colors, i.e. blue, green (or yellow) and
red, another multifiber 36 being constructed of fibers
38 adapted to transmit substantially only one other
primary color and a third multiliber adapted to transmit
substantially only the remaining third primary color.
The letters R, G and B, representing the colors red,
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107
gre~n, and hlue, inclicate a colored multlfiber arran~ement which, when
asse~blecl into a face~)lat-e structure such as is illustrated in Fig. 2, provides
an integration suitable for producing color m~xing (producinq full color images)
~cco~ding to the invention.
~ ibexs 38 ~ay be formed o~ recl, qreen (or yellow) and blue qlasses
or 7~1astic materials and inteqrated as ~ultifibers 36 by any well-known technique.
U.S. Patents ~70s. 2,992,516, 3,188,188; 3,119,678 and 3,837,824 illustrate the
making of qlass multifibers, for example.
Since the colored fiber groups (multifibers 36) must, for optimum
performance, be in a strict 1-1 geometrical corresponden oe at input and output
ends of in-tensifier 10, a relatively lar~e multitiber qroup size (e.~. 25-150
micron) is 7~referred. ~lemental fibers 38 for providing ~onochrcmatic images
of high resolution within each color dot (multifiber 36) are, however, pre-
ferably held to within 5-10 microns in diameter.
A desirab:le proximity focused intensifier (e.g. intensifier 10) maY
ccmprise vacuum tight faceplates 12 and 14 formed of 5-10 micron clear glass
fibers, the usual photocathode or photoreceptor, electroluminescent coating
26 (e.g. of "white" light phosphor or zinc su:Lfide activated with copper or
manganese) and input and output color plates :30~and 32 as describe~ above.
Ihose interested in details of suitable photocathodes or photore oeptors (i.e.
the preparation, properties and uses of photcemissive materials) may refer to
the publication entitled "Photoemissive ~aterials" (pages 113-127) by A.H. So~mer,
ished ~Y ~ohn ~iley ~ SQ~S. Inc. of ~7e~7 "ork, l~n~on, ~vdrey, q~ronto.
Other literature on the sibject includes the text of "Electronics for Industry"
(pa~e 17) by W.I. Bendz also published by John Wiley & Sons.
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In Fi~. 6, intensifier 10 is illustrated in use as
a color i~aye display device where, for example, an
lmage of an object 40 focused on one end 42 of a fiber
bundle (fiberscope) 44 and transmitted to emitting and
45 of bundle 44 may be imaged by lens 48 (Figs. 1 and
6) upon receiving face 30 of intensifie- 10 for intensi-
fication and full color display at emitting face 32 of
the intensifier.
Another application for which intensifiers of the
present type may be used is in conjunction with a
reflex view finder for motion picture or still cameras.
This would permit blnocular viewing o the view finder
image without the usual constraints on head or eye
position. Moreover, the image would be bright even with
lS the taking lens stopped down ox in low light level
photographic conditlons. It has the further advantage
of not letting light back thxough the reflex view
finder system where such unwanted light might fog the
film.
Other applications include low light level surveillance
or search systems for which monochromatic image intensifiers
have been used, i.e. militar~, police, marine, border
patrol, etc. This invention would add a minimum OL
space and cost to the device in such applications.
A modification of the invention is illustrated in
Fig. 4 wherein a multi-component (3-color) phosphor
layer 50 is substituted for coating 26 of E'ig. 1. By
such means, the output multi-color faceplate 32 of Fig.
1 may be elimina-ted. .~11 other parts of intensifier
lOa of Fig. 4 heing substantially identical to corre-
sponding parts of intensifier 10 of Fig. 10 have been
given like reference numerals.
It is required that the geometrical patterning of
the multi-color phosphor layer 50 be coordinated to the
geometrical structure of input faceplat2 30 similarly
to the above-discussed coordination of the faceplate 32
geometry with that of plate 30. To this end, input
faceplate 30 may be used to transfer its lntrinsic
geometry by copying means (e.g~ photographic methods~
to the phosphor "dot" pattern using photoresist methods
to deposit the "dot" pattern. The expression "dot" is
meant to be descriptive of a shape corresponding to the
cross sectional shape of a multifiber 36 of input plate
30.
~hose interested in photographic-photoresist
methods for forming various configurations of phosphor
coatings may refer to UO S. Patents Nos~ 3,139,340;
3;255,00~3; and 3,360,450.
The still further modification of the in~ention
which is illustrated in E`ig. 5 includes the addition of
an electron multiplier channel plate 52 intermediately
of photocathode 22 and phosphor coating 26. This is
also adaptable to the structure of Figs. 1 and 4 and is
energized by potential V2 (Fig. 5~ for increased in-
tensification of images produced at the emitting end 54
of intensifier lOb.
Thost~ Interested in the details ~'-f- channel plate
electron multipliers may reLer .o U. S. Patents ~os.
3,867,183; 3,979,621; 3,979,637; and 4,031,423.
. ~t should be appreciated that there are various
other modifications and/or adaptations Of ~he precise
forms of the invention here shown and that the foregoing
illustrations are not to be interpreted as restrictive
of the invention beyond that necessitated by the following
claims.
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