0)
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`Europadisches Patentamt
`
`European Patent Office
`
`Office européen des brevets
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`ULL
`0 554 643 Al
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`Gi} Publication number:
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`(2)
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`EUROPEAN PATENT APPLICATION
`
`’ @) Application number: 92836049.0
`
`6)
`
`int. CLS: AGTB 3/12, AG1B 1/04,
`A61B 1/26
`
`Date of filing: 05.02.92
`
`Date of publication of application:
`11.08.93 Bulletin 93/32
`
`Designated Contracting States:
`DE ES FR GB IT
`
`®
`
`Applicant: ISTITUTO NAZIONALE Dt OTTICA
`Largo Enrico Fermi No.6
`1-50125 Arcetri Firenze(IT)
`
`Inventor: Longobardi, Gluseppe
`Via dei Bardi n.20
`-50125 Firenze(IT)
`Inventor: Panzardi, Giuseppe
`Via Piagentina n.25/B
`1-50121 Firenze(IT)
`
`Representative: Mannucci, Gianfranco,
`Dott.-Ing. et al
`Ufficio Tecnico Ing. A. Mannucci Via della
`Scala 4
`
`-50123 Firenze (IT)
`
`@
`display and/or recording.
`
`&) High-sensitivity system for examining an object using a low Intensity light source.
`
`@) An equipment for retinal and choroidal angiog-
`raphy comprises means (1) for the illumination of the
`ocular fundus and means (23,25,27,29} for displaying
`and/or recording the image of the ocular fundus.
`
`receive the
`image intensification,
`for
`Means (19)
`image information originating from the ocular fundus
`and send an intensified image to said means for
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`EP0554643Al
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`Aank Xerox (UK) Business Services
`(3. 10/5.643.4. 1h
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`DESCRIPTION
`
`The invention refers to an apparatus for visu-
`alizing an object and/or recording images of said
`object under low lighting conditions.
`In the context of the present invention the word
`object designates not only an inorganic object, but
`also and in particular a tissua or an organ of a
`human or animal being.
`the invention refers to an
`More in particular,
`apparatus comprising in combination:
`- means for generating an electromagnetic ra-
`diation;
`first conveying means to send the electro-
`magnetic radiation to the object which has to
`be observed;
`second conveying means to send the image
`of said object to displaying and/or recording
`means.
`
`-
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`-
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`In many applications the object to be observed
`cannot be subjected to a high intensity irradiation,
`since this would damage the object or could cause
`ather problems. This is tha case, e.g. in the field of
`restoration and study of archaeologic objects, such
`as for example study of papyri.
`invention is to
`A first objact of
`tha present
`provide an apparatus which enables displaying
`and/or recording of images of objects using a light
`source, or anyway a source of electromagnetic
`radiation, having low intensity.
`In brief,
`in a first embodiment the apparatus of
`the present invantion is characterized by means of
`image intensification, combined to said image dis-
`playing and/or recording means, in order to trans-
`mit
`to said display and/or
`recording means an
`intensified image of the object.
`In the study of
`archaedogic objects, and particularly of papyri, the
`device according to the invention offers consider-
`able advantages.
`More particularly, at present in order to obtain
`photographic images by means of the fluorescent
`emission of papyri,
`it
`ts necassary to expose the
`papyrus to an UV-radiation for a tong time due to
`the very low intensity of the fluorescent emission of
`the inks on the papyri. This causes on the one
`hand a damage of
`the object under examination,
`due to the larga amount of energy received by the
`object. On the other hand, the images cannot be
`obtained in real
`time, due to the long exposition
`time and to the subsequent need of developing the
`photographic films.
`The device according to the invention allows to
`obtain images in very short
`time at
`the same
`intensity of the radiation used for illuminating the
`object. This also allows to record the images with a
`television camera system combined to the image
`intensifier.
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`the device according to the inven-
`Therefore,
`tion allows to perform a new method of examina-
`tion, characterized in that the image is intensified
`prior to displaying or recording it. This device and
`the relevant method can be used in any application
`wherein the object to be observed must be sub-
`jected to an UV-radiation which can cause to the
`object damages which are directly praportional to
`the time of exposure. In these cases the use of an
`image intensifier and of a television camera allows
`to obtain images in very short time, thus reducing
`the damage deriving fram the UV-radiation to a
`minimum.
`
`The inventiva concept mentioned above has
`heen further developed and improved in order to
`obtain particular advantages and to solve peculiar
`problems in the medicalfield.
`In the field of laryngoscopy if Is known to use
`an apparatus comprising an endoscope, a source
`of light for illuminating the organs to be displayed,
`first conveying means to send the light emitted by
`said source to the organs to be illuminated, second
`conveying means to send the image of said organs
`to displaying and/or recording means.
`Apparatus of this kind are used for studying
`and examining the vocal chords and in particular
`for studying thair functioning. For this purpose a
`stroboscopic light source is presently used, which
`is modulated by the sound vibration generated by
`the same vocal chords under examination.
`
`These known apparatus have the remarkable
`disadvantage of a low contrast of the image under
`examination, which is practically not recordable.
`Therefore, a further object of the present inven-
`tion is to improve an apparatus for endoscopy, and
`in particular for laryngoscopy, and more particularly
`for laryngastroboscopy,
`in order to overcome the
`disadvantages of the known devices.
`In brief, an apparatus for endoscopy, and in
`particular
`for
`laryngoscopy
`according
`to
`the
`present
`invention is characterized in that
`it com-
`prises means of image intensification combined to
`said displaying and/or recording means in order to
`transmit to said displaying and/or recording means
`an intensified image of said organs.
`Advantageously, the light source used is a stro-
`boscopic source.
`In order to allow easy insertion
`and easy handling of the endoscopy in the larynx,
`according to a particularly advantageous embodi-
`ment of the laryngoscopic apparatus according to
`the invention provision is mace for an image light
`guide to be combined to the endoscopy, which
`connects the endoscopy to the displaying means,
`which may comprise a television camera, a monitor
`and recording means for recording the detected
`and intensified image.
`The use of an imageintensifier in this specific
`application leads to particular results and advan-
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`tages. Actually, this makes recording of the images
`abtained by stroboscopic lighting possible, and in
`addition this lighting can be very low, so that the
`dimensions of the endoscope can be remarkably
`reduced. This randers endoscopy easier and less
`troublesome to the patient.
`Furthermore,
`in order to obtain specific infor-
`mation about the functioning of the vocal chords, it
`whould be appropriate to study the vibrations with-
`out the patient being hindered by the presence of
`the endoscope. For this purpose it would be appro-
`priata to introduce the endoscope into the larynx
`through the nose. According to the state of the art
`this is made difficult by the dimensions of
`the
`endoscopa. Moreover, when passing through the
`nose the endoscope is placed in a position with
`respect
`to the vocal chords which is extremely
`disadvantageous in term of
`illumination. A con-
`sequence of this is that it is practically impossible
`to obtain significant images through this route with
`endoscopes of the prior art. The endoscope ac-
`cording to the present invention overcomes these
`drawbacks since on the one hand it allows to
`
`reduce the dimensions of the endoscope, and on
`the other hand it allows to detect images with a
`high contrast even under conditions of very low
`illumination.
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`Problems related to the need of irradiating an
`organ with a light radiation in order to obtain an
`image of
`the organ for studying and diagnosis
`purposes arise also in the field of retinal angiog-
`raphy.
`A further object of the present invention is to
`solve the problems related to retinal angiography,
`which are briefly explained hereinafter.
`Fluoroscopic angiography is a medical photog-
`raphy technique which requires fairly sophisticated
`equipment. This technique is used in the pursuit of
`the objective of obtaining information for the study
`and understanding of the circulatory dynamics of
`the ocular fundus. For this purpose, a small quan-
`tity of
`tracer
`substance,
`for example sodium
`fluorescein,
`is injected intravenously into the pa-
`tient. After injection, the fluorascein anters into cir-
`culation and reaches the vessels which supply the
`fundus of
`the eye. Fluorescent emission by the
`fluorescein is stimulated by an appropriate method
`of illumination, in such a way as to make it possible
`to obtain images which may be recorded on film.
`Conversely, absorption images may also be re-
`corded. Tha two techniques, as illustrated in great-
`er detail below, enable different types of informa-
`tion to be obtained.
`
`Photography of the fundus is generally per-
`formed with a "fundus camera” capable of analyz-
`ing the fundus of the eye and of producing photo-
`graphic images. The use of a television camera to
`take television pictures may also be specified. The
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`field of observation is generally illuminated by an
`intermittent flashing light or by continuous laser
`light, which in all cases must be sufficiently intense
`fo be capable of exciting a quantity of fluorescein
`which is kept within very strict limits because of its
`low tolerability.
`An interference fitter with a suitably predeter-
`mined pass band is interposed betwaan the light
`source and the fundus of
`the eye. For
`retinal
`fluoroscopic angiography,
`two filters ara normally
`used: one transmits blue light betwaan 466 and
`490 nm, representing the absorption peak of the
`excitation of fluorescein;
`the other transmits be-
`tween 525 and 530 nm, where the emission peak
`of fluorescein is located.
`
`In order to avoid pseudo-fluorescence (due to
`the superimpasition of of the spectral bands of the
`filters), filters with a very narrow bandwidth, which
`are consequently highly selective, have been used.
`Normal interference filters for a narrow pass band
`(f0 + 2 nm) have a peak wavelength transmittance
`of
`the order of 40-45%, which means that high-
`power light sources are necessary in orderto have,
`following the interference filter, sufficient intensity
`to stimulate the emission of the fluorescein.
`To enable the structure of the ocular fundus to
`
`be displayed, three conditions must be present:
`a) the light must reach the structure;
`b} the structure must absorb or reflect the light;
`c) the adjacent structures must react
`in a dif-
`ferant way from the structure concerned,
`in or-
`der to provide the necessary contrast.
`the
`In order to reach the fundus of the eye,
`light must pass through the cornea and the ery-
`stalling lens, which becomes transparent for light
`with a wavelength above 320 nm. The various
`jayers of the fundus of the eye can be reached
`only with certain wavelengths. More particularly,
`with a wavelength of 460 nm only the anterior
`retina is reached, while the deep retina is reached
`with radiation with a wavelength of the order of 593
`nm, which penetrates to the pigmented epithelium.
`Red light radiation with a wavelength of 703 nm
`reaches the choroid.
`
`With infrared radiation (at approximately 800
`nm) it
`is possible to penetrate the pigmented epi-
`thelium of the retina and display the network of the
`vessels in the choroid. In this case, use is made of
`the absorption and fluorescence properties of a
`dye,
`indocyanine green (ICG), which has an ab-
`sorption peak at 805 nm and a weak fluorescence
`with a peak at 835 nm. By comparison with sodium
`fluorescein,
`the intensity of
`fluorascence of
`in-
`docyanine green (ICG) is thirty times lower. This
`means that a fluorescence observation at an in-
`
`lu-
`frared wavelength requires very high incident
`minous intensity and considerable quantities of dye
`ta be injected into the circulatory system of
`the
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`the absorption technique,
`patient. Consequently,
`rather than the fluorescence technique, has been
`used almost exclusively.
`However, as is known to persons skilled in the
`fluoroscopic choroidal angiography yields a
`art,
`body of data much greater than that provided by
`absorption choroidal angiography.
`In particular,
`whereas absorption angiographyis sufficient for the
`diagnosis of tumoral pathologies and for the moni-
`toring of
`laser treatment in said pathologies, and
`may be used in the above treatment with IR lasers,
`fluoroscopic angiography may be used to assess
`smaller changes in the choroidal vessel network
`and may be used advantageously for the diagnosis
`of sub-retinal neovascularizations and for tha study
`of macular pathologies. A single type of equipment
`is used for both the absorption and the fluoroscopic
`techniques.
`angiography
`fluoroscopic
`therefore,
`Clearly,
`permits better display of the choroidal vessel net-
`work. On the other hand, since the fluorescence
`signal of
`indocyanine green is fairly weak,
`it
`is
`necessary to use -
`in addition to high doses of
`tracer - very intense illumination (with a power
`which may exceed 300 W). Moreover,
`in the case
`of photographic recording,
`it
`is macessary to use
`particularly sensitive photographic film. The re-
`quirement for strong light sources fs
`further
`in-
`creased by the high absorption (up to 70% of the
`incident intensity) of the interference filters used.
`The use of strong light sources entails thermal
`effects both on the measuring equipment and on
`the environment, and also on the patient. Means of
`cooling therefore become necessary, particularly in
`order to safeguard the interference fitters which are
`particular sensitive to heat. The high power of the
`light sources, however, remains a cause of serious
`discomfort for the patiant subjected to this type of
`examination. The most recent types of fluoroscopic
`angiographs are provided with control means to
`periodically switch off
`the light source,
`thus en-
`abling the equipment to cool down.
`The light source (which may be an argon laser
`with an optical fibre, a flash lamp, or other) is used
`solely for the excitation of the fluerascence or for
`absorption examination.
`In order to position the
`field of vision correctly and to focus the device with
`respect to the patient's eye, it is necessary to have
`a light source of low power, typically 20 W, known
`as the alignment source. Alignment is carried out
`by observing the patient's eye through a suitable
`eyepiece while the light beam from the alignment
`source is directed against the fundus of the eye.
`When the correct position has been found,
`the
`alignment source is switched off and the high-
`power light source required to excite the emission
`of the fluorescent substance is switched on.
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`The invention relates to a device for retinal or
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`-
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`-
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`-
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`choroidal fluoroscopic angiography or for similar
`uses, which does not have the typical disadvan-
`tages of conventional systems, of which the follow-
`ing may be listed in particular:
`-
`the necessity of high incidant luminous inten-
`sity on the filters and the resulting necessity
`of cooling devices, with consequent equip-
`ment costs and discomforts for ihe patient;
`the necassity of injecting high doses of tracer
`into the patient;
`the difficulty of taking pictures with a televi-
`sion camera;
`the necessity of having a complex optical and
`illumination
`system comprising means of
`alignment and means of illumination.
`These disadvantages are overcome with a de-
`vice of the type specified in the preamble of the
`attached principal claim, wherein, furthermore, the
`means of displaying and/or of recording the image
`are associated with means of image intensification
`which intensify the image originating from the ocu-
`lar tundus and send said intensified image to the
`means of display and/or of recording.
`In this way all the above mentioned disadvan-
`tages of the conventional systems are overcome.In
`addition, numerous further advantages are obtained
`and will be evident to the person skilled in the art
`from the reading of the following text.
`In particular,
`it
`is possible to produce a device for fluoroscopic
`angiography which uses a single light source of
`limited power, for example 20 W electric. This light
`source may be used both for alignment and for the
`illumination of the fundus of the eye and the excita-
`tion of the tracer. The power supply may be at low
`voltage. Even when interference filters with high
`absorption are used, as a result of which the intan-
`sity incident on the fundus of tha eye is equal, for
`example, to only 0.7 mW optical, the image intensi-
`fier is capable of supplying a sufficiently amplified
`signal to tha means of display to permit detection
`by a CCD television camera. A monitor associated
`with the television camera enables the doctor to
`carry out the alignment and subsequently the ob-
`servation of the development of the circulatory dy-
`namics of the ocular fundus directly on the display
`unit, without any need for eyepieces or photo-
`graphic cameras. The television camera may be
`associated with means of magnetic
`recording
`which, i desired, enable the phenomenon to be
`viewed again and enable a data archive to be
`maintained if necessary.
`Image intensifiers known as the third-genera-
`type,
`using
`a GaAs
`(gallium arsenide}
`tion
`photocathode, are particularly suitable for applica-
`tion in the present invention. Tha spectral response
`of GaAs photocathodes covers the region fram 600
`ta $00 nm (which is the most useful range for the
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`raphy, an application to laryngoscopy and an ap-
`study of the deep retina and of the choroid), where
`plication to examination of an inanimate object.
`In
`the sensitivity -
`in other words the ratio between
`the drawing:
`the electrical output current and the intensity of the
`Fig.
`1
`is a diagram of a possible embodiment of
`incident
`light
`-
`is higher
`than that of a good
`the device for retinal angiography:
`photocathode of tha $20 type fitted on second-
`Fig. 1A is a diagram of a modified ambodiment;,
`generation intensifiers. Between 530 and 600 nm
`Fig. 2 is a schematic illustration of an image
`(in other words in the waveband useful for the
`intensifier;
`examination of the anterior retina) the spectral re-
`Fig. 3 is a diagram of a device for retinal an-
`sponse of GaAs photocathodes is approximately
`equal
`to that of
`the 520 photocathodes of the
`giography according to the state of the art;
`Fig. 4 is a diagram of an apparatus for laryn-
`previous
`generation.
`Furthermore,
`GaAs
`goscopy; and
`photocathodes provide a more marked contrast
`Fig. 5 shows an apparatus for studying an object
`than S20 photocathodesin the nearintrared region,
`by means of UV-radiations.
`thus permitting better fluoroscopic choroidal an-
`In the embodiment illustrated schematically in
`giography in this range.
`The gain of an image intensifier using a GaAs
`Fig. 1,
`the device comprises a continuous light
`source 1 of low power, for example 20 W electric,
`photocathode may be of the order of 40000, so that
`housed in a main housing body 3. The alignment
`it
`is possible not only to use a light source of very
`
`limited power, which therefore causes no discom- source transmits a light bearn R towardafilter
`20
`fort
`to the patient and does not require special
`carried by a filter support ring 7. The said filter
`cooling systems or high-wattage power
`supply
`support ring may be fitted with various interference
`fiters to be used for various types of observation.
`units, but also to decrease the quantity of tracer
`In particular, filters with pass bands centered on
`injacted into the patient, with obvious advantages
`the
`typical
`absorption
`and
`fluorescence
`from the toxicological viewpoint. The absence of
`wavelengths of the various tracers (fluorescein, in-
`large power supply units and cooling systems also
`docyanine green) used for observation of the var-
`makes it possible to preduce portable fluoroscopic
`ious layers of the fundus of the eye may be dis-
`angiographs.
`posed on said ring. One of the fitters carried by the
`Further advantageous embodiments of the de-
`ting 7 may be used beth for alignment and for
`vice according to the invention are indicated in the
`observation of the fluorescence phenomenon, After
`attached claims.
`In particular, the light source may
`the filter support ring 7 there is disposed a pair of
`be a light-emitting diode (LED), which emits radi-
`deflecting
`mirrors
`9
`freflecting)
`and
`11
`ation at a predetermined wavelength, instead of an
`incoherentlight source. In this way the necessity of
`(samitransparent), which deflect the beam toward
`the fundus of the patient's eye 0. The patient's eye
`using an interference filter is sliminated. This is
`is kapt in the corract position for observation of the
`possible because of the fact that with the image
`region of
`the fundus of
`the eye concerned by
`intensifier
`the luminous intensity of
`the emitting
`diode is sufficient for making the required observa-
`means of a viewing target whichis notillustrated.
`With an electric power of 20 W for the light
`tions. By providing a number of diodes used al-
`source 1, a continuous luminous intensity of 0.7
`fernately and selectively, it is possible to operate at
`mW reaches the fundus of the patient's sya. The
`a number of wavelengths with the same equipment
`and without the use of interference filters.
`electrical power and luminous intensity used are
`The invention also relates to a method com-
`therefora very limited and do not cause any prob-
`lems either in relation to the thermal effects on the
`
`-
`
`prising the steps of:
`-
`sending a beam of electromagnetic radiation
`to the object to be examined;
`sending the image of said object to display-
`ing and/or recording means:
`- displaying and/or recording said image.
`The invention provides for intensifying the im-
`age of the object and displaying and/or recording
`the intensified image.
`the
`of
`embediments
`Further
`advantageous
`methed according to the invention are indicated in
`the attached claims.
`
`The invention will be more clearly understood
`from the description and the attached drawing
`which shows practical, non-restrictive embodiments
`of the invention in an application to retinal angiog-
`
`50
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`interference filters or in relation to possible discom-
`fort for the patient.
`The light beam coming off the fundus of the
`patient's eye is sent through a set of correcting
`lenses 15 and a focusing optic 17 toward an image
`intensifier indicated in general by 19. Tha image
`intensifier 1$ amplifies the image, with a gain which
`may be equal
`to or greater than 40000, and the
`amplitied image is sent through a suitable optic 21
`to a CCDtelevision camera 23. The signal from the
`televisian camera may than be transmitted through
`an amplifier 25 to a moniter 27 and/or to means of
`magnetic recording 29. The viewing section in-
`dicated in general by 30, and comprising the focus-
`ing optic 17, the image intensifier 19, the optic 21
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`is mounted on a
`and the television camera 23,
`support 33 which is movable with respect to the
`main housing body 3. A focusing knob 35 enables
`the viewing section 30 to be moved with respect to
`the other optical components housed in the main
`body 3 to permit the focusing of the image.
`Fig. 2 is a diagram of an image intensifier
`which may be used as component 19 in the device
`in Fig. 1. These image intensifiers ara known in
`themselves for other uses. The intensifier in Fig. 3
`comprises a glass window 37 through which the
`incident baam passes. On the rear of the glass
`window there is deposited a GaAs photocathode
`39, which converts the photons of
`the incident
`image into electrons. After the photocathode 39
`there is disposed an amplifying system 41 for the
`aiectrons, consisting of a multichannel plate (MCP).
`The multichannel plate 41 consists of a very large
`number
`of microscopic
`conducting
`channels
`formed in a glass support and disposed in an
`orderly way in a disk with a thickness of 1 mm.
`Since gach microscopic channel is a separata high-
`gain electron multiplier, and since there is a one-to-
`one correspondence between the input face and
`the output face of the multichannel plate, the mul-
`tichannel plate intensifies the electronic image. The
`electrons leaving the multichannel plate 41 are
`subjected to a very strong electrical field between
`the plate 41 and a phosphor 43, and are thus
`“tired” at said phosphor 43, which converts the
`electrons back to photons which form the intensi-
`fied optical image. The phosphor 43 is associated
`with an opticalfibre system indicated in general by
`45, which is used to re-orientate the inverted image
`from the focusing optic 17 and to isolate the phos-
`phor 43 from the rest of the equipment followingit.
`By using an cage intensifier 19 it is possible,
`as demonstrated above, to use a light source 1 of
`limited power.
`In the embodiment in Fig. 1A (in
`which identical numbers indicate parts identical or
`corresponding to those of the embodiment in Fig.
`1) the light source consists of a set of three light-
`emitting diodes (LEDs) 1A, 1B, 1C. The light-emit-
`ting diodes 1A, 1B, 1C are supported by a movable
`member 2 indicated by broken lines (for example a
`slide} in such a way that
`they can be aligned
`alternately with the mirror 11. By using LEDs which
`emit at predetermined wavelengths,it is thus possi-
`bla fo avoid the use of interference filters, further
`simplifying the structure of the equipment. This is
`because each LED emits at one of tha wavelengths
`usable for the examination of the fundus of the eye,
`and the selection of the correct wavelength of the
`light source is made simply by positioning the
`correct LED in the optical path of the device. The
`LEDs which are not in usa may be kept switched
`off if necessary.
`
`Fig. 3 is a diagram of a device for fluoroscopic
`angiography according ta the state of the art. Fram
`a comparison of said davice with that shownin Fig.
`1, and also with the diagram in Fig. 1A, the differ-
`ences
`and the advantages obtained with
`the
`present invention will become clear. The device in
`Fig. 3 has a first alignment source oflimited power,
`indicated by X1, which is used to pasition the light
`beam with respect to the fundus of the patient's
`eye O. A second light source X2, which may be
`continuous or discontinuous (flash) and which may
`amit incoherent or coherent {laser source) light, of
`high power (possibly more than 300 W) is used to
`emit
`the light beam which, passing through the
`optical system consisting of the interference filter
`carried on the ring 7' and the deflecting mirrors 5",
`9, 11',
`is used to excite the fluorescence. 15°
`indicates a set of correction lenses corresponding
`to the lenses 15 of the device in Fig.1, while 30°
`indicates the viewing section which is movable with
`respect to the main body 3' by means of a focus-
`ing knob 35". The section 30" comprises an eye-
`piece 51, through which the operator cbserves the
`fundus of the patient's eye, and a pair of focusing
`lenses 17', 17" corresponding ta the lens 17 in Fig.
`1. A camera 53 is also provided, to capture images
`of
`the fundus of
`the aye. The image originating
`from the fundus of the patient's eye is sent to the
`eyepiece 51 and to the camera 53 by means of a
`system of mirrors §5 (semi-transparent) and 57
`(refiecting}. In the schematic representation in Fig.3
`the cooling systems and the power supply systems
`of the two light sources X1, X2 have been omitted.
`A comparison of the diagrams in Figs.
`1 and
`1A and in Fig. 3 makes it clear that the devices in
`Figs.
`1 and 1A have a much simpler structure
`(without the high-powerlight source, among other
`items) and permit much easier display and record:
`ing of the images, since alf observations, whether
`during alignment or during the examination of the
`circulatory dynamics, may be made conveniently
`through the monitor 27. Ht will also be noted that
`the use of a low-power source and of a CCD
`television camera which captures the image inten-
`sified by the intensifier 19 enables television pic-
`tures to be taken, making it possible to perform the
`whole analysis continuously and consequently to
`gather a quantity of information much greater than
`that normally possibla with the use of discontinu-
`ous photography. This is also of particular impor-
`tance in view of the fact that the tracer injected into
`the patient's circulatory system takes a vary short
`time to pass through the capillaries of the ocular
`fundus, so that the time interval in which the exami-
`nation may be made is very brief. Moreover, the
`progress in time of the process of re-emission of
`light by the tracer varies from patient to patient and
`is therefora unpredictable.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`HAAG-STREIT AG - EXHIBIT 1031
`Page 6 of 13
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`HAAG-STREIT AG - EXHIBIT 1031
`Page 6 of 13
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`4
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`EP 0 554 643 Al
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`12
`
`Fig. 4 very diagrammatically shows an appara-
`tus for laryngoscopy, and more particularly an ap-
`paratus for laryngostroboscopy using an image in-
`tensifying system.
`Laryngoscopy is a technique which involves
`special problems. Actually, 2 continuous light does
`not allow the oscillation of the vocal chords to be
`observed, and in order to examine all the physical
`properties of the vocal chords, such as frequency,
`amplitude or phase, stroboscopic systems must be
`used, i.e. stoboscopic lighting sources.
`Irrespect of whether flexible or rigid optic fibre
`endoscopes are used, the use of stroboscopic illu-
`mination (electronically synchronized with the os-
`cillation frequency of the vocal chords) lowers the
`contrast of the detected image with respect to the
`image obtained by continuous illumination. This
`randers vision difficult. The problem is solved by
`the apparatus of Fig. 4. In this figure, 101 denotes
`an endoscope of substantially usual type, to which
`a stroboscopic tight source 105 is combined. A
`bundle of optical fibres 102 conveys thelight from
`sourca 105 to the tip of endoscope +01. Reference
`number 107 designates a unit comprising an image
`intensifier 109, which can be of the type shown in
`Fig. 2, and a television camera 111. The unit 107 is
`connected fo a monitor and possibly to image
`recording systems, schematically shown at 113.
`Tha unit 107 is connected to the output of
`endoscope 101 by means of a flexible image light
`guide 115 in order to allow for an easier handling
`of the endoscops during use thereof. Said image
`light guide-115 has a one-to-one correspondence
`between the end oriented toward the endoscope
`101 output and the end which is in contact with the
`high sensitivity television system, represented by
`unit 107, The transmitted image is subjected to a
`spatial sampling so that the fibre density is suffi-
`ciently high in order not
`to eliminate the higher
`spatial frequencies. On the other hand,
`the very
`limited thickness of the coating allows the contrast
`at the end coupled to the endoscope to be main-
`tained.
`
`The intensified image coming from the image
`intensifier 108 provides a high contrast and a high
`luminosity even if the straboscopic source 105 has
`a low or very low intensity. This permits a direct
`visual observation and also a recording of images
`of
`the vocal chords, which images have a high
`content of information due to the use of the strobo-
`
`scopic source and which are not affected by the
`drawback of a low contrast typical of devices of the
`state of the art.
`
`Fig. 5 is a diagram of an embodiment of the
`device according to the invention, for use in study-
`ing objects by means of UV-radiation, e.g. ap-
`plicable for studying papyri or other archaeolagical
`objects.
`
`In the diagram of Fig. 5, 201 denotes a source
`of UV-radiation; 203 is a resting plane for
`the
`object O ta be examined; 205 is a focusing lens;
`215 is a unit which comprises an image intensifier
`219 (similar to the intensifier 19) and a television
`camera 221. The television camera 221 is com-
`bined to recording and/or displaying means for the
`datected image, said means are designated 223 as
`a whole and may include a moniter.
`It
`is to be understeed that the drawing illus-
`trates only an example provided solely as a prac-
`tical demonstration of the invention, it being possi-
`ble to vary this invention in its forms and disposi-
`tions without thereby departing fro