GB2207256A

GB2207256A - Microscope arrangement for arbitrary visual and optoelectronical analysis

Info

Publication number: GB2207256A
Application number: GB08810567A
Authority: GB
Inventors: Dr Gunther Thorwirth
Original assignee: Carl Zeiss Jena GmbH
Current assignee: Jenoptik AG
Priority date: 1987-07-17
Filing date: 1988-05-05
Publication date: 1989-01-25
Anticipated expiration: 2008-05-05
Also published as: GB2207256B; DD262721A1; DE3810639A1; GB8810567D0; DE3810639C2

Description

22072516 c i - MICROSCOPE ARRANGEMENT FOR ARBITRARY VISUAL AND

OPTOELECTRONICAL ANALYSIS The invention relates to a microscope arrangement for parallel (arbitrary) visual and optoelectronic analysis of input objects. It is particularly suitable for an automatic classification of objects included in microscope preparations, such as, for example, analyses of human blood, analyses of chromosome preparations, of inshore waters and in environmental protection.

Automatic processing of microscope images is of increasing importance in the field of biological and medical sciences. On the international market a number of automatic microscopes operating with electronic image processing are currently available, among them being the "Morphoquant" device of the VEB Carl Zeiss JENA.

Arrangements of and methods for the coherent- optical Fourier transformation in the processing of microscope images are known in the art. Despite some well documented classification results, as for example in analyses of chromosome preparations described by - Hutzler et al in "Processing ISKI", 1982 - Medical Image Interpretation, Munich 1982 Barkunov et al in "Avtometrija" 5, 1980 - Schwerdtner et al in "Bild und Ton 37" (12), 1984, coherent-optical microscope image analysis has not been generally accepted up to now for use in technical microscopes. There are two main reasons for this. Firstly, the considerable constructional volume (size) of the equipment necessary for coherent-optical image processing and, secondly, the necessity to suppress or minimize the associated coherent noise (Patent Specifications GB 1409731; US 3,482,102).

Apart from coherent-optical image processing procedures, incoherent-optical solutions have increased in importance (Patent Specifications US 1,281,075; US

3,288,018; US 3,390,257). Unfortunately, the arrangements suggested cannot be realized without considerable optical effort, and in some cases they require great mathematical effort for the electronic postprocessing, or are only effectively applicable with single-dimensional input objects.

In DD-Patent Specification No. 246,466 a device for the incoherent analysis of local spectrum regions is disclosed which can be attached to common microscopes as a complete "image processing module", an image converter and technical means being required additionally to project the real enlarged image of the i 1 i i i i i 1 i i 1 i 1 i j -3microscope preparation into the plane of the image converter. With such an arrangement, a visual observation of the microscope preparation - as is common in microscopy and is demanded by the users of automated microscopes - would not be feasible.

It is an object of 'the invention to analyse input objects with the help of an arrangement visually as well as optoelectronically, with minimum technical provisions.

The pesent invention also seeks to develop a microscope arrangement which permits the incoherent zone-sampling Fourier analysis of an input object, utilising optical modules which are common in microscopes and retaining the projection of the input object enlarged for visual observation.

According to the present invention, there is provided a microscope arrangement for an arbitrary visual and optoelectronic analysis, comprising an illuminating system, a condenser, an input object, an objective and a beam splitter dividing the bundle of rays into two partial beams, all components being arranged successively on an optical axis with the illuminating system being disposed in front of the condenser in such a manner that the part of the input object to be observed is illuminated homogeneously, together with an ocular, the optical axis of which X coincides with the axial beam of the first partial beam, and a receiver which is arranged behind a Bertrand lens on the axis of the second partial beam in a plane being a conjugated focal plane of the condenser, wherein the illuminating system comprises either a light source, a collector and an illuminated diaphragm of variable shape, which is arranged in the focal plane of the condenser and acts as an aperture stop, or a subdivided flat light emitter positioned in the focal plane of the condenser, the diaphragm or the subdivided flat light emitter, respectively, having at least one radiating zone which varies in size, form and/or position in temporal succession, and the receiver being a single detector.

Advantageously, the illuminated diaphragm of variable shape may be a liquid crystal display with various driveable radiating zones, and a polarizer in front of it and an analyzer following it. Using broad banded light it is preferable to arrange a coloured filter in front of the polarizer for contrast enhancement.

As a very simple variant, instead of a liquid crystal display, a diaphragm plate may be used as the illuminated diaphragm. To ensure that the radiating zone will vary in size, form and/or position in temporal succession, the diaphragm plate may be 1 i 1 1 i i i i i i i 1 i i i -5movable with respect to the optical axis, or it may be interchangeable with other diaphragm plates having radiating zones of different form and/or size. The diaphragm plate, advantageously, is removable from the optical light path to sufficiently illuminate the input object during a visual observation.

When applying a subdivided flat light emitter in the function of the illuminating system, it is of advantage to use an electroluminescent display the luminescent areas of which are driven arbitrarily.

If only one sampling location of the input object is to be evaluated during an incoherent zone-sampling Fourier analysis, it is preferable to arrange a tube diaphragm in a plane, being a conjugated object plane, and in front of the Bertrand lens. Further, it is advantageous if the single detector comprises a diaphragm and a photo-detector, the effective area of the photo-detector being determined precisely by means of the aperture. On the one hand, by means of the microscope arrangement according to the invention the input object is image enlarged, which therefore makes it available for a visual observation. On the other hand, the plane of the aperture stop of the condenser, in which either a subdivided flat light emitter or an illuminated diaphragm of variable shape is located, is imaged upon the optoelectronic receiver. The quantity 1 of light incident upon the receiver delivers a measured value which is determined by the radiating zone of the light source or the radiating zone of the diaphragm and by the input object. When using radiating zones of different size, form and/or position a number of measurements will form a measurement series that, as a carrier of the object information, permits the classification and the identification of microscopic objects included in the input object.

The particular advantage of the invention consists in the fact that the optical components and modules which are used are exclusively typical for microscopes, that no additional Fourier transforming lens and no separate image converter is required to perform a zone- sampling Fourier analysis. The illuminating system and the essential majority of the optical modules are utilized for both the imaging for the purpose of a visual observation and for performing the zone-sampling Fourier analysis, so that, a device being realized by means of the measuring arrangement according to the invention is therefore not considerably larger in size than a standard microscope. Moreover, standard microscopes may be easily converted to ensure an automatic evaluation of the input object by means of an incoherent zonesampling Fourier analysis.

i 1 i i 1 i 1 1 The present invention will now be further described in detail, by way of three examples and with reference to the accompanying drawings, in which:- Fig. 1 is a diagrammatic representation of a microscope arrangement according to the present invention including a diaphragm plate which, as an illuminated diaphragm of variable shape, forms the basic element of the illuminating system; Fig. 2 is a similar representation of a microscope arrangement according to the invention including a liquid crystal display as an illuminated diaphragm of variable shape; Fig. 3 is likewise a similar representation of a microscope arrangement incl'uidng an electroluminescent display as a subdivided flat light emitter; and Fig. 4 is an illuminating system including a diaphragm plate which permits variable positioning of a wedge-shaped transparent zone.

The microscope arrangement represented in Fig. 1 comprises a light source 1 of any kind, a collector a diaphragm plate 3 located in the focal plane of a condenser 4, an input object 5, an objective 6, a beam splitter 7 dividing the bundle of rays into two partial beams, an ocular 8 the optical axis of which coincides with the axial beam of one of the partial beams and a Bertrand lens 9 on the axis of the 2, X 1 i other partial beam which is followed by a receiver 10. The receiver 10 is arranged in a plane which is a conjugated plane of the diaphragm plate 3. The radiation coming from the light source 1 illuminates the input object 5, which can be visually observed via the objective 6, the beam splitter 7 and the ocular 8. For the purpose of an incoherent zone-sampling Fourier analysis, the diaphragm plate 3, which acts as an aperture stop, is imaged onto the receiver 10 via the condenser 4, the objective 6, the beam splitter 7 and the Bertrand lens 9. The quantity of light impinging upon the receiver 10 is defined by the form and the transparency of the microscopic objects included in the input object 5 and by the size, form and the position of the radiating zone of the illuminating system determined by the diaphragm plate 3. To obtain a series of measurements being typical of the object a number of different diaphragm plates 3 are inserted into the optical light path, or their position with respect to the optical axis is changed. In the present embodiment of the diaphragm plate 3 is blackened plate with an annular transparent zone as radiating zone 19 of the illuminating system. Corresponding to the number of measured values required, diaphragm plates 3 of different diameters of the transparent zones are inserted successively into 1 1 i 1 1 i 1 1 1 i 1 1 1 1 i i i i i i i i 1 j i 1 1 -9the optical light path. Any other form of radiating zone is also suitable. Of special advantage would be a wedge-shaped radiating zone 19 in the illuminating system (Fig. 4). In such a case any number of measured values is obtainable simply by step-wise rotation of the diaphragm plate 3 about the optical axis 20. For a visual observation it is useful to remove the diaphragm plate 3 from the optical light path.

A second embodiment is shown in Fig. 2. This example does not use a diaphragm plate 3 in the first embodiment, but has an illuminated diaphragm in the form of a liquid crystal display 11 in which the driven liquid crystal zones will rotate the polarization plane of the light by 90 degrees. Hence, there is no need to manufacture different diaphragm plates 3. In addition to those components and modules which are described in the first embodiment and are arranged in the same way in the example of Fig. 2, it is necessary to insert a polarizer 13 in front of the liquid crystal display 11 and an analyzer 14 following the objective 6. Tn the case of the polarizer 13 and the analyzer 14 being disposed mutually perpendicular, the illuminated diaphragm of variable shape generated by the driven elements of the liquid crystal display 11 is imaged onto the receiver 10. Additionally, the 1 -10transmitted bundle of rays illuminates the input object 5.

If this illumination is insufficient, the entire light quantity which is imaged via the collector 2 can be utilized for illumination purposes by, for example, switching off the liquid crystal display 11 and arranging the polarizer 13 and the analyzer 14 parallel to each other, or by moving the polarizer 13 and/or the analyzer 14 out of the optical path. A similar effect can be obtained by arranging the polarizer 13 vertically to the analyzer 14 and driving the entire liquid crystal display 11. A visual observation of the input object 5 is not then feasible at the same time with the incoherent zone-sampling Fourier analysis. If a light source 1, with a broad spectral bandwidth is used for illumination, it is of advantage to arrange, for example, a coloured filter 12 in front of the polarizer 13 to achieve a contrast enhancement.

The most favourable embodiment is represented in Fig. 3. In contrast to the examples shown in Fig. 1 and Fig. 2, where the illuminating system comprises a light source 1, a collector 2 and, alternatively, a diaphragm plate 3 or a liquid crystal display 11, in this third example the illuminating system is simply a subdivided flat light emitter in the form of an i i fl i i i i j 1 1 -11electroluminescent display 15. The components and modules which follow, namely are the condenser 4, the input object 5, the objective 6, the beam splitter 7, the ocular 8, the Bertrand lens 9 and the receiver 10, all arranged as has already been described above. Additionally, a tube diaphragm 16 is located in an image plane of the input object 5 and is directly positioned in front of the Bertrand lens 9. It is feasible to cut off the image by means of the tube diaphragm 16 such that only a predetermined section of the input object 5 determines the measured value. This is useful, for example, if the input object 5 includes several equal objects to be identified or classified.

A further diaphragm 17 is arranged directly in front of the receiver 10. This makes it feasible to predetermine the effective area of the receiver 10 precisely. For example, this effective area will be limited to an extremely small circle on the optical axis 20 of the microscope arrangement with a pinholediaphragm being used, which causes the size of the integration area appertaining to the measured value to be determined exclusively by size, for and/or position of the radiating zone 19 in the aperture stop plane.

Radiating zones 19 of different size, form and/or position are generated by means of driving different j luminescent areas to yield a number of different measured values. When applying an objective 6 being corrected to infinity it is necessary to dispose a tube lens 18 behind it.

An electronic control and evaluation unit, not shown in the drawings, will synchronize the operation of the electroluminescent display 15 and of the receiver 10 and will evaluate the measurment series obtained.

The evaluation of a large number of measured values ensures a higher reliability of object classification. For the purpose of object classification, within the evaluation unit, the measured values are compared to the values stored there which have been received previously by using known objects to be expected within the input object 5. For this purpose, radiating zones 19 are utilized which have a similar size. form and position relative to the optical axis 20 as in the actual evaluation process. The evaluation process is the same for all embodiments. It is carried out in the same way as in the already known arrangements for a coherent zone-sampling Fourier analysis, but with the difference that the integrally measured values are received in series, and this fact has to be taken into account, if necessary by means of buffering. In 1 principle, it is proposed to proceed according to one of the evaluation methods suggested by CASASENT, D. and SHARMA, V. in their publication "Fourier-Transform Feature-Space Studies", (Proceedings of SPIE, Vol 44o, Nov. 1983).

. 1

Claims

CLAIMS 1. A microscope arrangement for artibrary visual and optoelectronic analysis, comprising an illuminating system, a condenser, an input object, an objective and a beam splitter dividing the bundle of rays into two partial beams, all components being arranged successively on an optical axis and the illuminating system being disposed in front of the condenser in such a manner that the part of the input object to be observed is illuminated homogeneously, together with an ocular, the optical axis of which coincides with the axial beam of the first partial beam, and a receiver which is arranged behind a Bertrand lens and on the axis of the second partial beam in a plane being a conjugated focal plane of the condenser, wherein the illuminating system comprises either a light source, a collector and an illuminated diaphragm of variable shape, which is arranged in the focal plane of the condenser and acts as an aperture stop, or a subdivided flat light emitter positioned in the focal plane of the condenser, the diaphragm or the subdivided flat light emitter, respectively, having at least one radiating zone which varies in size, form and/or position in temporal succession, and the receiver being a single detector.

1 i 1 i i i j i I i 1 1 -is-

2. A microscope arrangement as claimed in claim embodying the illuminated diaphragm of variable shape, which diaphragm is a liquid crystal display having various driveable radiating zones, and which has a polarizer in front of it and an analyzer following.

3. A microscope arrangement as claimed in claim 2, wherein a coloured filter is arranged in front of the polarizer for contrast enhancement.

4. A microscope arrangement as claimed in claim 1, wherein the illuminated diaphragm of variable shape is an interchangeable or, with respect to the optical axis, a movable diaphragm plate which includes a transparent radiating zone.

5. A microscope arrangement as claimed in cl aim 4, wherein the diaphragm plate is removable from the light path for visually observing the input object.

6. A microscope arrangement as claimed in any one of claims 1 to 5, wherein the subdivided flat light emitter is an electroluminescent display, the luminescence areas of which are driveable arbitrarily.

7. A microscope arrangement as claimed in any one of claims 1 to 6, wherein a tube diaphragm is arranged in front of the Bertrand lens in a plane being a conjugated object plane.

Published 1988 at The Patent Office, State Housc. 66 71 High Holborn. London WC1R 4TP. Further copies inay be obtained frorn The Patent Office, Sales Branch, St Mary Cray. Orpington. Ken! BR5 3RD. Printed by Multiplex techniques ltd. St MuT Cray. Ken Con 1 87

1

8. A microscope arrangement as claimed in any one of claims 1 to 7, wherein the single detector comprises a diaphragm and a photo-detector.

9. Microscope arrangements substantially as herein described with reference to and as il lustrated in the accompanying drawings.

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i i 1 1 i i I Amendments to the claims have been filed as follows 17 2. A microscope arrangement as claimed in claim 1, embodying the illuminated diaphragm of variable shape, which diaphragm is a liquid crystal display having various driveable radiating zones, and which has a polarizer in front of it and an analyzer following.

is 5. A microscope arrangement as claimed in claim 4, wherein the diaphragm plate is removable from the light path for visually observing the input object.

6. A microscope arrangement as claimed in claim 1, wherein the subdivided flat light emitter is an electroluminescent display, the luminescence areas of which are driveable arbitrarily.