EP2207472A1

EP2207472A1 - Device for measuring fluorescent radiation on biological substances with a semi-conductor sensor arrangement

Info

Publication number: EP2207472A1
Application number: EP08837571A
Authority: EP
Inventors: Thomas Hennig
Original assignee: Ferton Holding SA
Current assignee: Ferton Holding SA
Priority date: 2007-10-01
Filing date: 2008-10-01
Publication date: 2010-07-21
Also published as: WO2009046923A1; DE102007047093B4; US8471221B2; US20100219354A1; DE102007047093A1

Abstract

The invention relates to a device for measuring fluorescent radiation emitted by biological substances, comprising a light source (18), a capturing unit (20), an evaluation unit (28) that is coupled to the capturing unit (20), at least one emission fibre (14) that is coupled to the light source (18), and at least one detection fibre (16) that is coupled to the capturing unit (20). Said emission fibre (14) guides excitation radiation to the biological substrate and the detection fibre (16) receives fluorescent radiation excited on the biological substance and guides it to the evaluation unit (28). According to the invention, the capturing unit (20) comprises a semi-conductor sensor arrangement (62) in which at least three sensors that are arranged inside a surface and that detect fluorescent radiation emitted by the biological substance in wave length areas that are separate from each other, are arranged. Data sets of at least two different reference measurements on at least two different biological substances are stored in the evaluation unit (28) that compares the measured measurement values to the stored data sets and issues a result relating to the pathological attacks of the examined biological substances and/or relating to the type of examined, biological substances.

Description

Device for measuring fluorescence radiation on biological substances with a semiconductor sensor arrangement

The invention relates to a device for measuring fluorescence radiation on biological substances according to the preamble of claim 1.

A device for measuring fluorescence radiation on biological substances is known, for example, from DE-A-42 00 741. The document discloses an apparatus for detecting caries on teeth, comprising a lighting unit which emits radiation in the wavelength range from 360 to 580 nm to a tooth. A filter transmits the fluorescence radiation returned by the tooth in a wavelength range greater than 620 nm. The transmitted radiation is evaluated for caries detection.

From DE-A-195 41 686 a further device for measuring fluorescence radiation is known in which a light source emits excitation radiation in a wavelength range between 600 and 670 nm to a tooth to be examined. The fluorescence radiation excited on the tooth is recorded and evaluated in a wavelength range between 670 and 800 nm.

The hitherto known devices have the disadvantage that in the case of an examination in the range of different or modified biological substances, inaccurate results can occur. The invention is therefore an object of the invention to provide a device of the type described above, are available in the more accurate measurement results in terms of change or deviations of the structure of biological substances. Biological substances can be endogenous substances or prosthetic materials.

To solve this problem serve the features of claim 1.

The invention advantageously provides that, in a device of the type described in the introduction, a receiving unit has a semiconductor sensor arrangement in which at least three sensors are arranged within a surface. The at least three sensors detect the fluorescence radiation emitted by the biological substance in separate wavelength ranges. The evaluation unit can store various data sets, preferably in the form of multidimensional, preferably three-dimensional measured values, wherein the evaluation unit compares the measured values measured with the data records and a result regarding the pathological infestation of examined biological substances and / or with respect to the type of biological Issues substances. Data sets of at least two different reference measurements on at least two different biological substances can be stored in the evaluation unit. In order for the evaluation unit to be able to output a result with regard to the type of biological substances examined, at least three reference measurements must be stored in the evaluation unit. The result is displayed by the display unit. Preferably, however, three or more reference measurements are provided on three or more different biological substances.

The emission and detection fibers can be both flexible light guides and rod lenses in an endoscope.

The at least one detection fiber may be arranged with the proximal end, preferably centrally over the semiconductor sensor arrangement at a distance from the surface of the semiconductor sensor array. The invention has the advantage that the sensors used detect the fluorescent radiation excited on the biological substance, in particular on a biological tissue, in three separate wavelength ranges and an evaluation unit evaluates this.

In the prior art, ratios of the measurement signals of the individual sensors are used in order to be able to output a result with regard to the pathological attack of examined biological substances. However, ratios of the measurement signals of the individual sensors can only map linear curves. Saved reference measurements can also describe non-linear waveforms and thus provide accurate information within a wide dynamic range.

More than two reference measurements allow to consider a wider range of different possible substances. Thus, e.g. endogenous substances and prosthetic materials different optical signatures, such. the fluorescence spectra of the substances, which should be evaluated in some diagnostic issues the same.

The deposit of at least three reference datasets allows a differentiated, diagnostic statement about the type of substance being studied.

The device according to the invention can be used to detect bacterial infestation of teeth. Because of the variety of oral tissue types or tooth materials with different restorative materials, a diagnosis based on the analysis of three spectral regions is much more accurate and reliable.

The device according to the invention can also be used to fix especially malignant tumors in an endoscopic examination. For this purpose, a photoactive substance, preferably 5-aminolevulinic acid (5-ALA), is introduced into the biological tissue to be examined. Stimulated by an excitation radiation, the biological tissue fluoresces and the malignant cells stand out clearly from the healthy tissue. Malignant cells mean cells of a malignant tumor. Due to the autofluorescence of the skin (autofluorescence), however, false results may occur. In an analysis based on three spectral ranges, this autofluorescence is detectable and discriminatable. In an analysis based on three spectral ranges, a diagnosis is possible even without prior introduction of photoactive substances.

In the device according to the invention it can be provided that the light cone emerging from the proximal end of the detection fiber illuminates the sensor area of the semiconductor sensor arrangement without interposing optical lenses.

This has the advantage over the prior art that the returned radiation does not have to be routed via separate optical fibers to different optical receivers, or has to be split by mirrors or other optical elements onto the optical receivers. The light cone emerging from the proximal end of the detection fiber can illuminate the sensor surface without interposing optical lenses.

The detection fiber is fixed by means of a light guide holder centrally above the semiconductor sensor arrangement and at a predetermined distance from the surface of the semiconductor sensor arrangement, wherein the light guide holder is attached to the housing of the semiconductor sensor arrangement.

The three sensors can be sensors for radiations, which respectively lie in the wavelength ranges of the primary colors red, green and blue. The three sensors can also be sensors for radiations, each lying in other wavelength ranges, i. H. in wavelength ranges of mixed colors.

The sensors can be arranged within a circular area and the respective base color can be assigned a circular area segment of 120 °.

This embodiment has the advantage that the returned radiation is uniformly distributed to the sensors, since the detection fiber is positioned centric to the semiconductor sensor array. However, the three sensors are not limited to being arranged inside a circle but may be arranged arbitrarily with each other.

The sensor for radiations in the wavelength range of the primary color red has the highest sensitivity and is sensitive to at least 750 nm.

This has the advantage that the weak compared to the green fluorescence red fluorescence is amplified, thereby reducing electrical crosstalk is reduced.

The sensors may consist of photoresistors, phototransistors, photodiodes and / or pyroelectric sensors. The sensors can have different spectral sensitivities. The sensors may also be made from color image sensors, e.g. CCD or CMOS exist.

An optical pre-filter for suppressing the excitation radiation can be arranged between the at least one detection fiber and the semiconductor sensor arrangement and fixed on the semiconductor sensor arrangement with the aid of an optically transparent potting compound.

The thickness of the optical pre-filter may be less than 2 mm. The pre-filter may be a dielectric filter.

The semiconductor sensor arrangement may also be arranged on a circuit board which is screened with an electrically conductive layer, preferably of copper, against electromagnetic radiation.

Any layer that shields against electromagnetic radiation can be used.

It can be arranged between the receiving unit and the evaluation three separate amplifier for amplifying the respective signals of the sensors.

The light source used may be an LED chip. LEDs, in contrast to lasers, emit light in a wide opening angle. Usual LED chips mounted on a substrate radiate in all directions.

The transmission of light in an optical fiber is effected substantially without changing the aperture angle, that is, the light as it exits the optical fiber has the same aperture angle as at the entrance.

In order to thus realize light with a wide opening angle at the exit side of the emission fibers, in a further exemplary embodiment coupling is dispensed with optical lenses and a distance of less than 0.3 mm, preferably between the LED chip and the proximal end face of the emission fiber 0 mm, provided.

By dispensing with optical lenses significantly more opening angle can be realized.

Between the LED chip and the proximal end face of the at least one emission fiber may be disposed a medium having a refractive index intermediate between that of the emission fiber and that of the surface of the LED chip. In this way, the reflection losses at the transitions are minimized. Advantageously, the introduced into the space medium is optically transparent.

In a further development, the proximal end surface of the emission fibers adjoining the light-emitting surface of the LED chip is smaller than the light-emitting surface of the LED chip and completely covered by the light-emitting surface of the LED chip.

In a further refinement, the LED chip emits light in the UV range and / or in the adjacent visible range, preferably violet light in the wavelength range from 390 to 420 nm. The radiation in this wavelength range can be particularly efficient in understanding the optical differences between healthy and visible light sources. uncover and infected teeth or malignant cells and healthy tissue.

The light source can emit periodically modulated light. The excitation radiation can be modulated in its amplitude, wherein the frequency of the amplitude modulation is about 2 kHz.

Between the receiving unit and the evaluation unit, three separate preamplifiers and / or at least one lock-in amplifier and / or at least one subtracter can be arranged.

The subtractor may be a hardware subtractor. This means that the circuit elements of the subtractor consist of concrete components, such. As resistors, capacitors or amplifiers. The advantage of a hardware subtractor is that the dynamic range of the measurement is fully available independent of an offset.

In a further embodiment, the emission and the detection fibers can have an acceptance angle greater than 35 °. Alternatively, the acceptance angle of the emission and detection fibers may be greater than 40 °, preferably greater than 45 °.

In the previously known devices, the substantially axial exit of the radiation from the respective light guide proved to be disadvantageous, since due to the substantially axial radiation exit sufficient irradiation of straight sections narrow cavities, e.g. Periodontal pockets, not possible. For this reason, additional optical elements are provided at the radiation exit end of the light guide in the hitherto known devices, which represent a significant manufacturing effort and significantly increase the overall diameter of the light guide.

The invention has the advantage that because of the large acceptance angle of the emission as well as the detection fibers bacterially infested sites or malignant cells in narrow cavities, such as. B. in periodontal pockets, are better detectable without additional optical elements. The acceptance angle greater than 35 ° corresponds to an opening angle of at least 70 °. The advantage of an acceptance angle of greater than 35 ° is that the bundle of emission and detection fibers of the present invention is suitable for irradiating also straight sections of narrow cavities without having to use additional optical elements. The maximum intensity achieved on a flat surface which runs perpendicular to the light exit surface is substantially higher in the case of the emission and detection fibers according to the invention which have an acceptance angle greater than 35 ° than in conventional quartz glass optical fibers which are not wide-angle light guides.

The emission and detection fibers can be coated one or more times.

The entire distal end face of the emission and detection fibers can be coupled to the proximal end face of at least one light guide element, wherein the light guide element made of sapphire or a mineral material or plastic and can have an acceptance angle greater than 35 °. The acceptance angle can also be greater than 40 °, preferably greater than 45 °. The entire distal end face of the emission and detection fibers and the proximal end face of the light-guiding element can be pressed against one another with the aid of a spring force.

The fluorescence signals of the light-guiding element can also be detected by the different sensors of the semiconductor sensor arrangement. By comparing the measurement signals generated by the sensors with the reference data sets of different materials stored in the evaluation unit, the material of the at least one light-guiding element can additionally be identified. The evaluation unit can output which material the light-guiding element consists of.

This has the advantage that the information of which material the light-guiding element consists can be passed on to a software. Among other things, this software determines the sensitivity with which the measured values are evaluated. The passing on of the information to the software has the advantage that the sensitivity of the measurement is adapted to the material of the light-guiding element. that can. This means that the sensitivity with which the measured values are evaluated can be adapted to the application.

The light-guiding element can be guided within an inspection probe, which has a shaft and a coupling part. The inspection probe may be connected to a handpiece and the junction between the entire distal end face of the emission and detection fibers and the proximal end face of the light guide member may be within the handpiece. The light source can also be located inside the handpiece.

The light-guiding element can be rigid or flexible.

The light-guiding element can guide the excitation radiation emitted by the light source via the emission fibers to the biological substance and also the fluorescence radiation emanating from the biological substance.

The light-guiding element may consist of a single optical fiber or of a plurality of optical fibers, i. consist of a fiber optic bundle.

The total diameter of the individual optical fiber or the total diameter of the optical fiber bundle may be greater than or equal to the total diameter of emission and detection fibers.

As an alternative to the light guide, the emission and detection fibers may be directly, i. without interposition of a light-guiding element, up to the biological substance z. B. be performed in an endoscope. The emission and detection fibers can also be guided at the distal end within an inspection probe with shaft and coupling part. The shaft can be rigid or flexible. It can also be flexible or bent. The shaft may be formed as a protective tube.

The two aforementioned embodiments with inspection probe facilitate handling, since the bundle of emission and detection fibers or the light guide due to the curved shaft easily in z. B. periodontal pockets can be introduced. The emission and detection fibers may terminate with the distal end of the shaft or protrude a maximum of about 5 cm from the shaft.

In a further embodiment, it is provided that the proximal end of the inspection probe can be connected to a handpiece, wherein the emission and detection fibers can be guided within the handpiece.

This has the advantage that the device is easier to handle, since the bundle of emission and detection fibers can be guided better due to the handpiece.

The light source may be disposed within the handpiece.

In a further development, it is provided that the length of the emission fiber or the total length of the emission fiber and the light-guiding element is less than 60 cm, preferably less than 10 cm.

These embodiments have the advantage that the emitted light does not have to travel long distances from the light source to the biological substance, since in the case of wide-angle light guides, the intensity of the radiation decreases with increasing length of the light guide.

In the following, embodiments of the invention will be explained in more detail with reference to the drawings:

They show schematically:

1 is a schematic block diagram of the device according to the invention,

2 shows a device with semiconductor sensor arrangement,

3 shows a block diagram of the device with receiving unit, amplifier, subtractor, evaluation unit and display, 4 shows a representation in which the light source is an LED chip,

5 is a schematic block diagram in which the light source is arranged in the handpiece,

6 shows a device with light-guiding element,

7a shows a wide-angle light guide whose axis is aligned parallel to a flat surface,

FIG. 7b shows a quartz glass light guide, which is not a wide-angle light guide, and whose axis is aligned parallel to a flat surface, FIG.

8 is a representation with light distribution on the flat surface of Fig. 2a and Fig. 2b,

Fig. 9 is an illustration showing the relationship between attenuation of the illuminance and length of the light guide.

Fig. 1 shows a schematic block diagram of a device according to the invention for use in the dental field. Excitation radiation from the light source 18 is coupled into a bundle of emission fibers 14 and transported by this to a tooth 1. The emission fibers 14 are guided together with detection fibers 16 in an optical fiber cable 12. The fiber optic cable 12 is coupled to a handpiece 10 at the distal end. The emission fibers 14 and the detection fibers 16 are guided in the handpiece 10 and in an inspection probe 2. The inspection probe 2 consists of a coupling part 6 and a shaft 4. The proximal end of the coupling part 6 can be connected to the distal end of the handpiece 10. The shaft 4 may preferably be made of metal or plastic. The fluorescence radiation excited at the tooth 1 by the excitation radiation is transported via detection fibers 16 to a receiving unit 20. The emission and detection fibers 14, 16 preferably terminate at the distal end 8 with the distal end of the shaft 4. At most, the emission and detection fibers 14, 16 protrude by approximately 5 cm from the second shaft. In the receiving unit 20, the fluorescence radiation is detected in three separate wavelength ranges and converted into three electrical signals. These are supplied via separate preamplifier 22, a lock-in amplifier 24. By means of the lock-in amplifier 24 downstream subtractor 26 background signals can be subtracted. Background signals are produced by reflection of the excitation radiation at the distal end 8 of the emission and detection fibers 14, 16 and by a slight intrinsic fluorescence of the optical fibers and the adhesives used. The size of this signal is directly proportional to the excitation radiation. If the excitation radiation is kept constant, the result is a constant offset signal. This background signal is measured during the switch-on routine of the measuring device and eliminated in the subtracter 26 before the evaluation. Within the evaluation unit 28 is a memory 27 in which three-dimensional measured values of healthy tooth material, diseased tooth material and artificial filling material are stored. Three-dimensional means that for each measured value, the radiation intensities in three spectral ranges z. B. in the spectral regions of the primary colors red, green, blue are measured. The currently measured three-dimensional measured value is compared with the stored comparative measured values and the distances to the closest comparative measured value of healthy dental material and / or artificial filling material and diseased dental material are determined. The ratio of the distance between the currently measured value and the closest comparative measured value of healthy dental material or artificial filling material and the distance between the currently measured value and the closest comparative measured value of diseased dental material is displayed in the form of values on a display unit 29. The user knows that if this value is smaller than a certain value, the examined tooth area is free from bacterial residues.

A device according to the invention for detecting particularly malignant tumors looks similar to the device described in connection with FIG. One difference is that no handpiece 10 and no inspection probe 2 are used. The optical fiber cable 12 is coupled to an endoscope at the distal end. The emission and detection fibers 14, 16 are guided inside the endoscope and close at the distal end from the distal end of the endoscope or over a maximum of about 5 cm from the distal end of the endoscope over. The endoscope can be introduced into the human body, for example, for the examination of the bladder or for the examination of other body cavities.

FIG. 2 shows a bundle of detection fibers 16, which are positioned centrally via a semiconductor sensor arrangement 62 according to the invention and at a defined distance from the surface of the semiconductor sensor arrangement 62 with the aid of a light conductor holder 68. The optical fiber holder 68, which is not shown here, attached to the housing of the semiconductor sensor assembly 62. The semiconductor sensor arrangement 62 has three sensors, which are arranged within a circle, which detect the fluorescence radiation excited at the tooth via the emission fibers 14 in three separate wavelength ranges and convert them into three electrical signals. The three sensors are sensors for the primary colors red, green and blue. The respective primary color is assigned a circle segment of 120 °. The distance between the end face of the detection fibers 16 and the surface of the semiconductor sensor array 62 ensures complete illumination of the three sensors. The distance between the end surface of the detection fibers 16 and the surface of the semiconductor sensor array 62 may be less than 2 mm when using wide-angle light guides. Between the detection fibers 16 and the semiconductor sensor arrangement 62, a prefilter 64 for suppressing the excitation radiation can be arranged. The pre-filter 64 is fixed on the semiconductor sensor assembly 62 by means of an optically transparent potting compound.

Fig. 3 shows a block diagram of the device according to the invention. The detection fibers 16 which guide the radiation returned by the tooth are positioned centrally via a semiconductor sensor arrangement 62 at a defined distance from the surface of the semiconductor sensor arrangement 62. The semiconductor sensor arrangement 62 has three sensors arranged within a circle, which detect the fluorescence radiation excited on the tooth or in the periodontal pocket via the emission fibers 14 in three separate wavelength ranges and convert them into three electrical signals. These are, as also shown in FIG. 1, fed via separate preamplifiers 22, a lock-in amplifier 24 and a subtracter 26 to an evaluation unit 28. There, the measured values are compared with comparison measured values stored in a memory 27 and a value is output which can be displayed on a display 29. If the value is above a certain value, it means that the tooth has bacterial infestation.

4 shows an LED chip 40, which is coupled opposite to the emission fibers 14. That is, less than 0.3 mm, preferably 0 mm, spacing remains between the LED chip surface and the proximal end face of the emission fibers 14. Between the LED chip surface and the emission fibers 14, a not shown, preferably transparent medium, for. As a resin, may be arranged, the calculation index between which the E- missionsfasern 14 and the LED chip surface is located. With the help of the transparent medium, z. B. a curable plastic, the emission fibers are mechanically fixed to the LED chip 40 and optically coupled. The LED chip 40 is mounted by means of an electrically conductive adhesive 46 on a monitor diode chip 50 and electrically contacted. The monitor diode 50 supplies a measured variable proportional to the optical output line of the LED chip 40. From an electrical contact point 48, a bonding wire 44 is connected to an insulated electrical connection pin 54 guided in the base 52. The monitor diode 50 has a second electrical contact, which is guided as Gehäusepin 56 to the outside. The LED chip 40 also has a second electrical connection. This connection is made via a bonding wire 42, which is connected to an isolated in the base 52 outboard electrical connection pin 58.

Alternatively, the structure of FIG. 4 can also be executed without a monitor diode 50. In this case, the electrical contact point 48 and the bonding wire 44 with the isolated in the socket pin 54 would be omitted.

So that the radiation losses of the excitation radiation can be kept low, in one exemplary embodiment, in FIG. 5, which is similar to the exemplary embodiment from FIG. 1, the light source is arranged inside the handpiece 10. This has the advantage that the length of the emission fibers 14 is very short executable. The emission fibers 14 and detection fibers 16 are brought together at the distal end of the handpiece 10. At the distal end, an inspection probe with shaft and coupling part connects, in which the emission 14 and Detektionsfasem 15 are guided. Distally, the emission and detection fibers terminate with the distal end of the shaft. The fluorescence radiation excited at the tooth 1 is transmitted from the tooth 1 via the detection fibers 16 to a receiving unit 20 located in the device 17. The detection fibers 16 are guided from the proximal handpiece 10 to the receiving unit 20 in the optical fiber cable 13. In Fig. 5, the light source of Fig. 4 is used.

FIG. 6 shows a block diagram which is very similar to that of FIG. 5, with the difference that the end face of the bundle of emission and detection fibers is coupled to the end face of a light-guiding element 9.

The light guide 9 is guided within a centering device 15 and projects at the proximal end of the centering device 15 out of this. The centering device 15 and thus the light-guiding element 9 are pressed against each other with the bundle of emission and detection fibers 14, 16 within a plug-in and coupling element 11 by a spring. Such a plug and coupling element 11 may be a commercially available ST plug, which has a bayonet holder. The plug-in and coupling element 11 is located within a handpiece 10. The light-guiding element 9 is pushed back by the length projecting beyond the proximal end of the centering device 11 into the first coupling part 7. Since the light-guiding element 9 is fixed or glued within the shaft 4 and / or the distal end of the coupling part 6, the light-guiding element 9, which in this case is a flexible plastic optical fiber, bends inside the coupling part 6. The light-guiding element 9 stands by the bend under tension, which causes the light-guiding element 9 to be pressed permanently against the bundle of emission and detection fibers 14, 16. This ensures a good coupling of the radiation from the bundle of emission and Detektionsfasem 14, 16 in the light guide 9 and vice versa.

At the junction, the excitation radiation from the emission fiber 14 is coupled into the light guide element 9. The light-guiding element 9 is guided inside an inspection probe 2. The inspection probe 2 consists of a shaft 4 and a coupling part 6. The light-guiding element 9 can terminate at the distal end with the distal end of the shaft 4 or protrude distally therefrom, wherein it protrudes a maximum of 30 mm from the first shaft 5. The light exiting distally from the light-guiding element 9 illuminates the tooth section to be examined. The light returned by the illuminated tooth section is picked up by the distal end of the light-guiding element 9 and guided via the detection fibers 16 to a receiving unit 20.

Alternatively, the light guide 9 may also consist of sapphire or other mineral materials. The connection between the light-guiding element 9 and the bundle of emission and detection fibers 14, 16 can also take place without bending the light-conducting element 9, in particular if the light-guiding element 9 is rigid. The light-guiding element 9 and the bundle of emission and detection fibers 14, 16 can have a crowned end face in order to enable a better coupling of the light.

Also, the light guide may consist of several optical fibers, d. H. the light guide consists of an optical fiber bundle. These light guides may each have a diameter of about 30 microns. These optical fibers may also consist of sapphire or other mineral materials or plastics.

Also, in addition to the fluorescence signals of the illuminated tooth sections, the fluorescence signals of the light-guiding element 9 can be detected by the receiving unit 20. These latter fluorescence signals are then also converted into electrical signals. These are fed to the evaluation unit 28 via separate preamplifiers 22, a lock-in amplifier 24 and a subtractor 26. In the memory 27, which is located within the evaluation unit 28, three-dimensional measured values of the materials of various possible light-guiding elements 9 can additionally be located. The measured fluorescence signals of the light-guiding element 9 can be compared with the stored measured values. In this way it can be determined from which material the light-guiding element 9 is made. The sensitivity of the measurement can be adapted to the material of the light-guiding element.

An inventive device for detecting, in particular malignant, tumors looks similar to that described in connection with FIGS. 5 and 6 written out devices. One difference is that no inspection probe 2 is used. In each case, an endoscope is coupled to the distal end of the handpiece 10. The emissive and detection fibers 14, 16 are guided within the endoscope and terminate at the distal end with the distal end of the endoscope or protrude more than 5 cm from the distal end of the endoscope. The endoscope is insertable into the human body for examining body cavities.

FIGS. Figs. 7a and 7b show a cone of light of a lightguide representing a wide angle light guide and, in comparison, the light cone of a conventional silica glass waveguide which is not a wide angle light guide. The central axis 34, 36 of the two light guides are at a distance of 300 microns parallel to a flat surface 30. The diameters of the optical fibers are each 210 microns. The wide-angle optical fiber emits the light with an opening angle of 120 °, which corresponds to an acceptance angle of 60 °. The conventional quartz glass optical fiber, which is not a wide-angle optical fiber, has an opening angle of 25 °. The light intensities on the flat surface 30 are highest in the areas where the lines 35 and 37 meet the flat surface 30.

Glass waveguides having an acceptance angle greater than 35 °, preferably greater than 40 °, are preferably used as the wide-angle optical fiber. However, it is also possible to use wide-angle plastic optical fibers, preferably polystyrene.

Fig. 8 shows the light distributions on the flat surface 30 of Fig. 7a and Fig. 7b. The light exit surface, ie the free end of the optical fibers, is located on the abscissa at the value 0. The white dots represent the light intensity distribution for conventional quartz glass optical fibers with an aperture angle of 25 °, the black squares represent the light intensity distribution for wide-angle optical fibers with an aperture angle of 120 °. Significant differences between the two curves can be seen. An opening angle of only 25 ° leads to a flat curve. The maximum light intensity achieved on the flat surface 30 has approximately a distance between 1.5 mm and 2 mm from the light exit surface of the light guide end at an opening angle of 25 °. In the case of an opening angle of 120 °, the maximum achieved on the flat surface 30 Light intensity a distance of only about 0.3 mm from the optical fiber end. The maximum intensity achieved on the flat surface is more than five times higher in the case of the wide-angle optical fiber used in a device according to the invention compared to the maximum intensity of a conventional quartz glass optical fiber, which is not a wide-angle optical fiber. This means that much more accurate measured values can be determined, since the signal-to-noise ratio is significantly better. In the case of a wide-angle optical waveguide, as is evident from FIGS. 7a and 7b, the examined surface section is significantly shorter and better illuminated than with conventional quartz glass optical waveguides which are not wide-angle light guides. The ratio of bacterially contaminated area to area under investigation has a direct influence on the measured values, ie, if the bacterially contaminated area is small compared to the surface area under investigation, the contamination is difficult because of the small percentage of contaminated area to the total area surveyed read from the measured values. Small impurities can therefore easily be overlooked when using conventional quartz glass optical fibers having a large surface area under inspection and low illumination, as shown in FIG. 8. For wide-angle light guides with a relatively short surface section and intense illumination, the ratio of contaminated surface to surface area examined in terms of percentage is more favorable, so that contaminated surfaces are clearly and accurately detectable. For this reason, the tooth sections to be examined, in particular in narrow cavities, can be examined more precisely with a wide-angle light guide according to the invention.

FIG. 9 shows the illuminance at the end of different light guides relative to the illuminance at the entrance of the light guides as a function of their length. The relative illuminance was calculated according to the following formula:

B = NA ² * l0- ^{{{o * L) n0)}

B: Illuminance

NA: numerical aperture a: attenuation of the optical fiber in dB / m

L: length of the light guide in m The open circles refer to a wide-angle optical fiber with an opening angle of 120 °. This wide-angle optical fiber has an attenuation of about 17 dB / m in the range of 400 nm. The black dots refer to a quartz glass fiber with an opening angle of 25 °. This quartz glass optical fiber has an attenuation of about 0.1 dB / m in the range of 400 nm.

It can be seen from FIG. 9 that long optical fibers, especially in the case of wide-angle light guides, lead to a weakening of the light available at the exit surface in the short-wave spectral range around 390-420 nm, which is interesting for fluorescence excitation. The optical fiber should, in order to avoid this attenuation, have a length of less than 60 cm, preferably less than 10 cm, when using a wide-angle optical fiber. Thus, in contrast to conventional quartz glass fiber optics, which are not wide-angle light guides, an approximately 10 times higher illuminance could be achieved.

Claims

claims

1. Apparatus for measuring the fluorescence radiation emitted by biological substances, with

a light source (18),

a receiving unit (20),

- An evaluation unit (28) which is coupled to the receiving unit (20), at least one emission fiber (14) which is coupled to the light source (18), and at least one detection fiber (16) coupled to the receiving unit (20) wherein the emission fiber (14) conducts an excitation radiation to the biological substance and the detection fiber (16) receives the fluorescence radiation excited by the biological substance and conducts it to the evaluation unit (28),

characterized ,

in that the receiving unit (20) has a semiconductor sensor arrangement (62) in which at least three sensors are arranged within a surface which detect the fluorescence radiation emitted by the biological substance in separate wavelength ranges, data sets of at least two different ones being present in the evaluation unit (28) Reference measurements are stored on at least two different biological substances and the evaluation unit (28) compares the measured values measured with the stored data sets and outputs a result regarding the pathological infestation of the examined biological substances and / or in terms of the type of biological substances studied.

2. Apparatus according to claim 1, characterized in that the data sets are stored in the form of multi-dimensional, preferably three-dimensional measured values.

3. Apparatus according to claim 1 or 2, characterized in that the from the proximal end of the detection fiber (16) emerging light cone illuminates the sensor surface of the semiconductor sensor assembly without interposition of optical lenses.

4. Device according to one of the preceding claims, characterized in that the detection fiber (16) by means of an optical fiber mount over the semiconductor sensor array (62) and at a distance to the O- berfläche of the semiconductor sensor array (62) is fixed, wherein the optical fiber mount to the housing the semiconductor sensor assembly (62) is attached.

5. Device according to one of the preceding claims, characterized in that the three sensors are sensors for the primary colors red, green and blue, wherein the sensors are arranged within a circular area and the respective base color is assigned a circular area segment of 120 °.

6. Device according to one of the preceding claims, characterized in that the sensor for the primary color red has the highest sensitivity and is sensitive to at least 750 nm.

7. Device according to one of the preceding claims, characterized in that the sensors may consist of photoresistors, phototransistors, photodiodes and / or pyroelectric sensors, wherein the sensors have different spectral sensitivities.

8. Device according to one of the preceding claims, characterized in that an optical pre-filter for suppressing the excitation radiation between the at least one detection fiber (16) and the semiconductor sensor assembly (62) is arranged and fixed on the semiconductor sensor assembly (62) by means of an optically transparent potting compound is.

9. Apparatus according to claim 8, characterized in that the thickness of the optical prefilter is less than 2 mm.

10. Apparatus according to claim 8 or 9, characterized in that the pre-filter is a dielectric filter.

11. Device according to one of the preceding claims, characterized in that the semiconductor sensor arrangement (62) is arranged on a circuit board, which is shielded with an electrically conductive layer, preferably made of copper against electromagnetic radiation.

12. Device according to one of the preceding claims, characterized in that between the receiving unit (20) and the evaluation unit (28) three separate amplifiers for amplifying the respective signals of the sensors are arranged.

13. Device according to one of the preceding claims, characterized in that the light source (18) is an LED chip (40).

14. The device according to claim 13, characterized in that the LED chip (40) light in the UV range and / or visible range, preferably violet light in the wavelength range of 390 nm to 420 nm, emitted.

15. Device according to one of the preceding claims, characterized in that the light source (18) emits periodically modulated light and the frequency of the amplitude modulation is about 2 kHz.

16. Device according to one of the preceding claims, characterized in that between the receiving unit (20) and evaluation unit (28) has three separate preamplifier (22) and / or at least one lock-in amplifier (24) and / or at least one subtractor (26 ) are arranged.

17. The apparatus according to claim 16, characterized in that the subtractor (26) is a hardware subtractor.

18. Device according to one of the preceding claims, characterized shows that both the emission (14) and the detection fiber (16) have an acceptance angle greater than 35 °, preferably greater than 45 °.

19. Device according to one of the preceding claims, characterized in that the entire distal end face of the at least one emission fiber (14) and the at least one detection fiber (16) is coupled to the proximal end face of at least one light guide element (9), wherein the light guide element (9 ) consists of a single optical fiber or a fiber optic bundle.

20. The device according to claim 19, characterized in that the light guide element (9) is guided within an inspection probe (2) having a shaft (4) and a coupling part (6).

21. Device according to claim 19 or 20, characterized in that the fluorescence signals of the light-guiding element (9) can be detected by the three sensors of the semiconductor sensor arrangement (62) and that by comparison of the measuring signals generated by the three sensors with those in the evaluation unit (28). stored reference data sets of different materials in addition, the material of the light-guiding element (9) is also recognizable and the evaluation unit (28) outputs from which material the light-guiding element (9).

22. The device according to claim 21, characterized in that the sensitivity of the measurement is adapted to the material of the light-guiding element (9).

23. Device according to one of the preceding claims, characterized in that the length of the at least one emission fiber (14) or the total length of the at least one emission fiber (14) and the light-guiding element (9) is less than 60 cm, preferably less than 10 cm ,

24. Device according to one of claims 1 to 18, characterized in that the emission and detection fibers (14, 16) at the distal end in within an inspection probe (2) with shaft (4) and coupling part (6) are guided.

25. Device according to one of claims 20 to 24, characterized in that the proximal end of the inspection probe (2) to a handpiece (10) is connectable, wherein the light source (18) within the handpiece (10) is arranged.