DE202013011877U1 - microscope system - Google Patents

Abstract

A microscope system (1) adapted to provide a digital result image and comprising means (R, L, 41) for providing microscopic images at different numerical apertures and a digital image capture unit (50), characterized in that the image capture unit (50) is arranged thereto is to capture at least two microscopic images at different numerical apertures in the form of digital frames and each corresponding image areas of the digital frames with respect to their sharpness to each other, in each case the image areas of the digital frames are combined with the highest image sharpness to the digital result image.

Description

The present invention relates to a microscope system having means for providing microscopic images at different numerical apertures, according to the preamble of claim 1 protection.

State of the art

Known microscopes, for example stereomicroscopes with optical zoom, are often equipped with means for physical limitation of the beam and thus for setting the pupil diameter or the numerical aperture. For example, rigid or variable aperture stops (e.g., irises or LCD panels) and / or suitable beam limiters on lenses and lens frames may be provided for this purpose.

The present invention relates both to microscopes in which the numerical aperture of one or more optical channels is variably adjustable by means of suitable aperture stops, as well as to microscopes which have two or more separate optical channels with a respective rigid aperture stop. Both are microscopic systems that have means for providing microscopic images at different numerical apertures.

The numerical aperture determines three essential characteristics of an optical image, namely resolution, brightness and depth of field:

The maximum resolving power of a microscope in the focal plane of the objective is limited by the light diffraction, which in turn is determined by the numerical aperture of the imaging system. The maximum resolution R, expressed in line pairs per millimeter (LP / mm), is proportional to the numerical aperture nA. It is simplified R = 3,000 × nA. High resolution therefore requires a high numerical aperture.

At the same time, when looking at objects that are not perfectly flat, the depth of field is also important, ie, the sharpness of the object areas that lie outside the focal plane. This decreases for geometric reasons with increasing numerical aperture and follows the numerical aperture reciprocal. For the visual insight, the depth of field DOF is described by Berek's empirical formula. According to this, DOF = λ / (2 × nA ² ) + 0.34 / (M _tot × nA), where λ denotes the wavelength of the light and M _tot the total visual magnification. The wavelength λ and the depth of field DOF are given in mm, for example. A high sharpness in image areas above or below the focal plane is then achieved with reduced numerical apertures.

The detected light cone determines the brightness I. Simplified, I = c × nA ² , where c represents a constant. High image brightness is again achieved with high numerical aperture. However, especially in digital image capture, the image brightness can be flexibly adjusted and adjusted in addition to the numerical aperture, exposure time, gain, gain, or digital post-processing. These adjustments are known to the person skilled in the art and are therefore not explained further.

However, at least in terms of resolution and depth of field, there is a conflict of objectives with conventional microscopes.

From the DE 10 2006 036 300 B4 and the DE 10 2006 036 768 B4 Stereomicroscopes of the telescope or Greenough type are known, which offer the observer a pair of images whose frames are well resolved differently (hereinafter also referred to as "asymmetric" stereomicroscopes). One of the frames has a higher numerical aperture and therefore a higher resolution in the focal plane, while the other frame with lower numerical aperture provides a better depth of field. These images are received simultaneously by the two eyes of the observer. Through the brain, the image pairs are assembled in such a way that the observer perceives the respectively better resolved detail from the two images. It exploits a physiological phenomenon in image fusion in the human brain.

Digital imaging devices do not perform this image fusion and use only the capture of a fixed aperture image. They usually capture exactly one image, based on a beam geometry and the resolution and depth of field defined with it. The focus areas of images of such digital image recording devices, ie the areas in which a corresponding object is sharply imaged, are therefore much narrower. This is not satisfactory compared to a visual stereoscopic image impression by a stereomicroscope. The ability of the human eye to accommodate up to ± 5 dioptres also results in a multiplicatory drawback in digital imaging over visual considerations.

The state of the art in conventional wide field microscopes (without stereo ray paths) addresses these problems by so-called z-stacking, wherein the focus position of the microscope during the recording of a picture sequence is gradually shifted. However, this requires either moving the object table with the object or moving the microscope relative to the object. In any case, a considerable mass must be moved (microscope on the z-drive or sample stage), which makes the process expensive in terms of both time and equipment. The time required in turn prevents the implementation as a live image, which is particularly disadvantageous in a movement of the user in the x-, y- and z-direction as well as in the observation of living cells.

In addition, with (normally) non-telecentric recording conditions, the magnification of the object changes as the focal position changes. The images taken by z-stacking therefore do not overlap exactly due to the variation of the image scale and must be adapted to each other by correlation or stretching or compression. This process involves uncertainties and possibilities of error for the picture to be merged.

In particular, in view of the currently observed strong trend towards digital microscopy, the object of the invention is to overcome the disadvantages mentioned and to enable improved image acquisition.

Disclosure of the invention

Against this background, the invention proposes a microscope system which has means for providing microscopic images at different numerical apertures as well as a digital image acquisition unit with the features of patent claim 1. Preferred embodiments are the subject matter of the dependent claims and the following description.

Advantages of the invention

The invention relates to recording and merging of microscopic images of different resolution and depth of field provided at different numerical apertures. The invention enables both a recognition of the finest structures and a topographical description of an object with the greatest possible quality and little effort.

The invention as a whole provides a microscope system which has means for providing microscopic images at different numerical apertures as well as a digital image acquisition unit. The microscope system is characterized in that the image acquisition unit is set up to capture at least two microscopic images at different numerical apertures in the form of digital single images and to compare corresponding image regions of the digital individual images with regard to their image sharpness. In each case, the image areas with the highest image sharpness are combined to form the digital result image. Due to the creation according to the invention, this has a higher image sharpness in a larger number of image areas than any of the digital individual images from which the image areas were selected. It thus also has a higher overall sharpness than the digital frames and advantageously combines the sharpest areas of the digital frames.

As already mentioned, the "means for providing microscopic images at different numerical apertures" can be, for example, one or more optical channels, for example stereo channels of a stereomicroscope, in each of which the numerical aperture can be variably adjusted by means of suitable aperture stops. Microscopes which have two or more separate optical channels with a respective rigid aperture stop or without aperture stops, but with different numerical apertures, accordingly have means for providing microscopic images at different numerical apertures.

In contrast to known microscope systems, improved results images can be generated by means of the present invention, the information content of which exceeds considerably that of pure (single-frame) sequences, and yet can be obtained with reduced effort. In contrast to the above-described microscope systems of the prior art, the present invention is particularly suitable for use in "single-channel" microscopes, or for image acquisition via only one channel of a stereomicroscope, if in each case at least one adjustable aperture diaphragm is provided here. With the present invention, it is therefore possible to produce high-quality result images with comparatively little expenditure on apparatus.

In particular, with respect to the known from microscopy and initially explained z-stacking no significant masses must be moved in the context of the present invention. The invention provides in the worst case at best, the adjustment of an aperture between the recording of different digital frames before. If a two-channel recording - with different numerical apertures in the individual channels - is possible, this is not necessary, so that in this case no parts of the microscope have to be moved at all.

The "at least two microscopic images", with an adjustable aperture diaphragm obtained and detected by means of the digital image capture unit in the form of the corresponding digital frames, can also be referred to as "aperture series". A reasonable number for the "at least two" digital frames depends on the particular set microscope parameters, such as the magnification used, which in turn defines the depth of field. For example, two, four, six, eight, ten, fifteen, or twenty frames can be shot. Another parameter which determines the number of digital single images to be recorded is here the number of adjustable apertures, ie the positions of a setting device of a corresponding aperture stop and the apertures which can be effected thereby.

According to the invention, it is therefore provided to record at least two individual images which are provided at different numerical apertures digitally and to combine them into a digital result image. The digital image recording takes place for example with the CCD chip of a camera or a line sensor. The invention may also include, for example, multiple digital frames at one aperture or multiple times in a fixed numerical aperture channel. As a result, for example, a resolution improvement can be achieved because noise effects of the image sensor used are reduced. However, at least two of the frames are provided at different numerical apertures, so that, as described below with reference to the attached Figs 3 explained in more detail, combine both the advantages of high resolution with high numerical aperture and the large depth of field with low numerical aperture.

The invention also offers particular advantages over the known from the photography HDR method (High Dynamic Range), in which several shots are combined to form a "super-picture" with increased brightness and contrast range. However, HDR methods only affect the local image exposure, not the image sharpness. However, HDR methods can also be used within the scope of the present invention, whereby additional image information can be obtained.

In photography, with the choice of aperture, the depth of field is merely used as a pictorial formative. However, the optical conditions in microscopy are fundamentally different from those of photography because the sharpness in photography is not limited by the diffraction. Therefore, closing the aperture in the photograph does not mean a decrease in the resolution in the focal plane, as can be observed in microscopy. In photography, an increase in the depth of field is rather achieved with quasi-constant resolution in the focal plane. Therefore, photography does not pose the problem of reduced resolution. Therefore, in photography, for maximum resolution and depth of field, it is only necessary to close an aperture accordingly. Photographic and microscopic beam paths as well as image acquisition and image processing options are fundamentally different and subject to different physical laws, limits and requirements.

The creation of the result image of the microscope includes, as mentioned, selecting the different image areas used for composing the result image on the basis of a comparison of their image sharpness. For example, local contrast values or other values characterizing the image sharpness can be used for this purpose. This may, for example, also be a numerical index (score) that indicates an image contrast or a sharpness in an image region of a digital single image. Since a comparison is made between the digital frames, this score can also be expressed as a percentage or relative value (for example, relative to the first correspondingly examined digital frame or the one with the highest image sharpness). The microscope system according to the invention can thus work very rapidly by means of known image processing algorithms, which can be implemented, for example, in the image capture device itself and / or in a control computer that controls it.

The mentioned comparison can be supplemented by further method steps. Thus, the digital individual images can also be examined by means of a suitable image acquisition unit by means of suitable image evaluation methods, corresponding values being determined for the image regions or the entire individual image which characterize the image sharpness. If these exceed, for example, a minimum default value or if they reach a level that can be displayed on a display system, then it is no longer sensible to make a comparison. As a result, processing time can be saved in the sense of a dynamic image display.

A corresponding microscope system can work particularly quickly if the image acquisition unit is set up to define the corresponding image regions on the basis of a predetermined position in the at least two digitally captured individual images. For example, each of the digital frames may be identically divided into arbitrary blocks of pixels, for example, 5x5, 10x10, 50x50, or 100x100 pixels (or corresponding non-square blocks of pixels). Each pixel block corresponds to one image area and can be compared to a corresponding image area of another frame. A predefinition can also take place, for example, in the form of image coordinates and / or pixel regions. For comparison, therefore, no image evaluation must be made beforehand, and corresponding comparisons can therefore be very fast.

It may also be advantageous to subject the individual images to image content recognition in a correspondingly configured image acquisition unit and to determine the corresponding image regions on this basis. For example, in the investigation of three-dimensional structures against a flat background, such as a digital component or a biological structure, an image content detection can be performed, by means of which the digital component or the biological structure is recognized as an image area. This corresponds to a known image segmentation. In areas that are "uninteresting" for the respective examination purpose, for example the flat background, no comparison is made, which saves further processing time. Of course, correspondingly recognized image contents as explained above can also be examined in the form of pixel blocks.

Merging two or more frames provided at different numerical apertures into a new digital result image with optimized local sharpness is accomplished by electronic image processing. For example, the image area of the individual images can be scanned in total, and the best-resolved pixel can be determined for each small local area and its image information can be transferred to the resulting image.

If, as stated above, pixel blocks are defined in the form of a grid, their respective size, i. the size of the corresponding image areas are made dependent on different factors, which relate both to the image itself and the performance parameters of the imaging device used, the bus system, the displaying monitor and / or an evaluating control computer. An individual preselection by a user and / or on the basis of an expected resolution may be possible in each case. The provision of the digital result image can be adapted, for example, to the display on a digital image display unit, wherein the size of the respective image regions is selected so that the displayable resolution of the image display unit is not exceeded and thus unnecessary computing power is consumed. Corresponding limitations, however, can also be taken into account when taking the digital single images and their resolution.

The adjustment of the corresponding raster width depends essentially on the object texture and its topography: For strong topographies and edges, a smaller raster width and for weak textures or image noise a larger raster width can be used. This too is covered by the explained use of an image content recognition, which is included for determining the mutually corresponding image areas of the digital individual images. Such a raster width can therefore also be applied unevenly across the image field of the digital individual images (but identical in all digital individual images). When composing the image areas of the individual images, the edges of the raster edges obtained can each be adapted by interpolation, so that a homogeneous transition results.

In particular, the invention makes it possible to achieve a significant increase in sharpness in the resulting image without having to make assumptions about the object, as in other digital reproductions, and thereby to be at risk of artifacts (e.g., in known edge sharpening). Since the image obtained merely consists of a synthesis of generic recordings (possibly even of the same channel), the result images obtained by means of the microscope system according to the invention are to be accorded an unrestricted "truth content" with at most minimal artifacts.

The determination of the sharpness value or of a variable characterizing the image sharpness may include, for example, determining a sharpness or resolution value by means of a contrast-based method. If information about image content is available, only a portion of the image of interest may be subjected to a similar process.

It may be particularly advantageous to additionally change a focus setting of a main objective of the microscope system when recording the at least two individual images. The microscope system according to the invention is therefore also suitable in combination with a conventional z-stacking method. In this case, one image per z-plane can be recorded, however, it is particularly advantageous to carry out the measures proposed according to the invention in different z-planes, so that in each case sharpness-optimized result images are obtained at the different z-planes. These can in turn be charged to another sharpness-optimized image. This results in a further improvement over known z-stacking method, because the maximum achievable resolution (with open aperture) is maintained.

The means for providing the microscopic images at different numerical apertures may be formed for example as separate stereo channels in stereomicroscopes. In this case, in the two stereo channels, in each case a plurality of digital individual images of the object can be recorded at the different numerical apertures by means of a detection module of the image acquisition unit, in each case by adjusting a variable aperture diaphragm. Correspondingly improved partial images are thus obtained for each stereo channel. In other words, a digital result image can be created from the individual images, but separated for the two stereo channels. This also makes it possible to correspondingly improve stereoscopic images which are suitable, for example, for viewing by means of a stereoscopic viewing unit.

However, it may also be provided to use an "asymmetric" stereomicroscope explained above with two stereo channels with different numerical apertures. One frame of a stereo channel can be combined with one frame of the other stereo channel. The capture of the images in the stereo channels can be done simultaneously.

Thus, completely separate imaging systems can be used as means for providing microscopic images at different numerical apertures that capture the same object area (possibly at different perspective angles). Microscope systems of the telescope or Greenough type (ie stereomicroscopes) are accordingly suitable as typical application forms for such parallel image recordings.

In a microscope system according to the invention, therefore, the at least two microscopic individual images provided at the different numerical apertures can be recorded simultaneously in the form of the two digital individual images, wherein at least two acquisition channels are used. In this case, each of the two channels can be assigned an image acquisition module of the image acquisition unit, for example a chip in each case a chip housing. However, instead of using two completely separate imaging systems, an imaging beam path can also be divided into multiple channels which are fed to different imaging modules.

In the case of a simultaneous image recording, in particular also moving objects with high dynamics can be recorded, which, however, is more complex in terms of apparatus than a sequential recording in which the at least two individual images provided at the different numerical apertures are recorded one after the other. In a sequential recording, advantageously, an aperture is adjusted between the at least two shots. This can be done completely automatically, for example by means of control signals of a corresponding control unit, for example a control computer.

The usable aperture diaphragm can be designed, for example, as an iris diaphragm or as an electronically controllable LCD transmission element.

Advantageously, in a microscope system according to a particularly preferred embodiment of the invention, a control device is provided, by means of which the image acquisition unit can be controlled in such a way that it receives at least two digital individual images which are provided at respectively different numerical apertures. For example, such a control device can also be set up to adjust an adjustable aperture diaphragm.

Advantageously, by means of the control device, in each case a number of digital single images to be recorded and, if provided, at least one adjustment amount for the aperture stop can be predetermined. Furthermore, the control device is set up to control the image acquisition unit in such a way that a recording of the digital individual images and an adjustment of the aperture diaphragm by the adjustment amount can be carried out alternately. A corresponding control unit can also be designed to adapt the exposure time or the gain of the digital image acquisition unit to the respectively selected aperture change, so that an equal brightness of the recorded image is ensured at the different numerical apertures.

In particular, the microscope system according to the invention, as mentioned, is designed as a stereomicroscope with at least two stereo channels, wherein each of the stereo channels is associated with a detection module of the image acquisition unit.

The invention is illustrated by means of embodiments in the drawing over the prior art and will be described in detail with reference to the drawings.

figure description

1 shows a schematic diagram of the beam paths of the stereo channels of a stereomicroscope, in which an image acquisition according to an embodiment of the invention can be made.

2 shows a schematic diagram of a beam path of an optical channel of a microscope, in which an image capture according to an embodiment of the invention can be made.

3 shows a relationship between resolution, numerical aperture and depth of field in the form of a diagram.

4 shows in a microscope system according to an embodiment of the invention implemented steps in the form of a schematic flowchart.

5 schematically shows a stereomicroscope, in which an image capture according to an embodiment of the invention can be made.

In the figures, corresponding elements carry identical reference numerals and will not be explained repeatedly for the sake of clarity.

Embodiments of the invention

The image acquisition according to an embodiment of the present invention may, for example, take place via one or both stereo channels of a telescope-type stereomicroscope. The components of such a stereomicroscope with the additionally provided according to an embodiment of the invention elements are in 1 shown schematically.

Corresponding stereomicroscopes have, for example, a common main objective 21 on, the two identically formed stereoscopic channels L and R are connected downstream. In a focus plane of the main objective is an object to be viewed 11 arranged. This in 1 shown stereomicroscope is symmetrical, which means that the stereomicroscope has two stereo channels L, R, which correspond to each other structurally. Therefore, in the 1 optionally the elements of the left stereo channel L and the elements of the right stereo channel R explained. The explanations, however, relate to both stereo channels L, R in the same way.

However, the invention can also be used with particular advantage in stereomicroscopes in which one or more elements of the two stereo channels L and R are formed differently from one another, for example in the US Pat DE 10 2005 040 473 B4 described. The invention can also be used in stereomicroscopes of the Greenough type.

A corresponding stereomicroscope can therefore comprise, as a means for providing microscopic images at different numerical apertures, two identically formed stereo channels L and R with an individually or jointly adjustable aperture diaphragm (s.u.) or two stereo channels L and R designed differently at least with respect to the numerical aperture.

The beam paths of the stereo channels L, R are in the 1 each by a schematic representation of the marginal rays 61 corresponding light beam 60 illustrated. The marginal rays 61 of the left stereo channel L are dashed, those of the right stereo channel R shown dotted. The optical axes are each shown in phantom and with 62 designated. A common center axis is designated M.

The main objective 21 is a zoom system 30 each with four optical groups 31 to 33 and 38 in both stereo channels L, R downstream. The main objective 21 and each four optical groups 31 to 33 and 38 are shown in a highly schematic manner and in practice may in particular each comprise a plurality of optical lenses. The four optical groups 31 to 33 and 38 The two stereo channels L, R can each be mechanically coupled together and, if movable (see below) can be adjusted with common adjusting means. Zoom systems 30 , as they can be used in the context of the present invention are, for example, in the US Pat. No. 6,816,321 described.

The first optical group 31 of the zoom system 30 acts collecting and thus focusses between the main objective 21 and the respective first optical group 31 of the zoom system 30 afocal running beam path. In stereomicroscopes, such an afocal beam path is often between the main objective 21 and realized on the image side thereof provided components, so that there is a particularly good adaptation option for additional components. However, as explained, the invention is also suitable for microscopes without an afocal beam path.

At least one of the optical groups 31 to 33 is each designed to move the magnification factor axially movable. By "axial" is meant in the context of this application, a direction, respectively from the focal point of the main objective 21 Starting vertically through the main lens 21 runs. The axial direction is thus through the main objective 21 Are defined. It corresponds in the in 1 illustrated example of those of the optical axis 62 the beam paths of the stereo channels L, R on the image side of the main objective 21 , In the illustrated example, for example, in each case the first optical group 31 of the zoom system 30 fixed, ie not be formed axially movable.

Image side of the first optical group 31 of the zoom system 30 is in each case a second optical group 32 provided, which has dissipative properties. By means of the second optical group 32 of the zoom system 30 is in each case by the first optical group 31 focused and thus convergent beam path widened. The second optical group 32 is, for example, along the optical axis 62 (ie in the axial direction) designed to be movable.

Next image side is in each case a third optical group 33 intended. This acts again collecting and focused by means of the second optical group 32 of the zoom system 30 scattered beam path again. Also the third optical group 33 of the zoom system 30 can each be along the optical axis 62 (ie in the axial direction) be designed to be movable.

The zoom system 30 In the example shown, in each case lenses 38 or corresponding optical groups of a plurality of lenses as the fourth optical group, which by the third optical group 33 of the zoom system 30 Focused and thus convergent beam path in each case expand so far that also on the image side of the zoom systems 30 an afocal beam path is present.

Between the second optical group 32 and the third optical group 33 of the zoom system 30 is in each case an adjustable aperture diaphragm 41 intended. The aperture stops 41 in the stereo channels L, R can in an especially controllable formed aperture unit 40 be arranged, the one or more mechanical and / or electronic inputs 42 has, over which a glare signal can be received. The diaphragm signal can be used to set a diaphragm diameter of the adjustable aperture diaphragms 41 be used. A corresponding signal 41 can in particular by an image capture unit 50 which is explained in detail below, or from a control computer 80 who is the image capture unit 50 and / or the entire microscope system via communication channels 81 controls, be issued.

However, as mentioned, the apertures in both stereo channels L, R may also be fixed and have a different diameter.

In the example shown, the aperture stops 41 the left L and right R stereo channels are set differently, leaving a viewer with his eyes 97 through eyepieces 96 (see below) looks into the illustrated stereomicroscope, can perceive an image with improved resolution and depth of field due to the above-explained physiological phenomenon.

On the image side of the zoom system 30 is a decoupling unit 70 shown, which is a preferably adjustable proportion 63 of the light of the two stereo channels L, R to an image acquisition unit 50 couples out. It should be emphasized that a corresponding decoupling unit need not be arranged in the illustrated position. A decoupling unit 70 for example, in a tube 90 be integrated (see below). Instead of for the image capture unit 50 certain decoupled share 63 The light of the two stereo channels L, R can also be the light intended for presentation to a viewer from the axial direction, ie with respect to the optical axes 62 to be decoupled. In the latter case, that for the image capture unit 50 certain proportion 63 continue in the axial direction. In each case, any diversion can also take place. A microscope designed exclusively for digital image acquisition can also be used without a decoupling unit 70 be formed so that the light of the two stereo channels L, R completely the image acquisition unit 50 can be made available.

In the example shown, that for the image capture unit 50 certain decoupled portion 63 the light of the two stereo channels L, R at an angle of 90 ° with respect to the optical axes 62 decoupled. For this purpose, for example, in both stereo channels L, R semitransparent mirrors or prisms 71 be provided. Optionally, only light of a stereo channel L, R by means of a partially transparent mirror 71 or prism can be decoupled. The decoupled share 63 of the two stereo channels L, R can be decoupled in separate channels (not shown), so that an image acquisition unit 50 , for example by means of two image acquisition modules 52 (see below, eg CCD chips) can each receive a stereoscopic partial image. This can also be two image acquisition units 50 be used.

The decoupled share 63 the light of the two stereo channels L, R can also be converted into a common beam path, wherein, for example, in each case the light of one of the stereoscopic channels L, R in the image acquisition by means of the image capture unit 50 can be hidden. For this purpose, for example, an optical unit 73 be provided, for example, the alternately actuated shutter 74 having. The image capture unit 50 can thereby capture both stereo channels L, R alternately. Alternatively or in addition to shutters 74 For example, differently oriented polarization filters in the optical unit can also be used 73 be provided, the subsequent selective detection of light of the two stereoscopic channels L, R by means of the image capture unit 50 but do not disturb a visual view. For this purpose, this example, with a variable adjustable polarizing filter 51 be provided. Also the optical unit 73 is expediently through the image capture unit 50 and / or the control computer 80 via one or more mechanical and / or electronic inputs 75 controllable.

It should be emphasized that the presentation here is very schematic. If the arrangement shown implemented directly, it would possibly be a problem in stereo operation, ie if both shutter 74 are open. The right semitransparent mirror or the corresponding prism 71 would then force the light of the left channel L forcibly also (although not desirable) in the right channel R partially upwards, which would interfere with the stereo viewing. For such a case, the partially transmissive mirrors or prisms would 71 be aligned so that they reflect the light out of the paper plane out (ie no penetration of the stereo channels takes place). The decoupled channels can then be superimposed outside the paper plane by means of a further beam splitter and coupled into the digital image acquisition unit.

About a deflection mirror 72 or a corresponding prism becomes the decoupled portion 63 the light of one or both stereo channels L, R in the multiply mentioned image acquisition unit 50 irradiated, if necessary by means of the polarizing filter 51 filtered, and by a corresponding optical group 53 on an image acquisition module 52 focused. As mentioned, two or more image acquisition modules can also be used 52 be provided. Are in the optical unit 73 for example polarization filter 74 provided, each of the two or more image acquisition modules 52 have a complementary filter, so that only selectively light of a stereo channel is detected. With appropriate orientation of the image acquisition unit 50 can also be on the deflecting mirror 72 or a corresponding prism can be dispensed with.

The decoupling unit 70 is subordinate to an insight unit, for example, a tube 90 includes. The zoom system 30 , the decoupling unit 70 and the viewing unit may be partially disposed in a housing to which the main lens 21 or a corresponding lens mount can be screwed on and / or attached, for example, by means of a dovetail receptacle. The Insight Unit, especially the tube 90 , Can also be mounted with a corresponding receptacle on a corresponding housing. Also the decoupling unit 70 can be modular.

The tube 90 includes each Tubuslinsen 91 , which intermediate pictures 95 produce. The tube lenses 91 In each case, reversing systems are subordinate 92 for image erection. On the image side close each eyepieces 96 at. The tube lenses 91 are designed to each parallel light bundles on a point 94 in the level of intermediate images 95 to focus. The point 94 is located in the front focal point of the eyepieces 96 and is imaged to infinity, so that he can see with his eyes 97 a viewer can be considered.

A corresponding stereomicroscope can be used for purely digital optical detection of an object 11 be formed, wherein the mentioned detection unit 50 also on the image side of the tube 90 can be arranged. The reversal systems 92 for image erection are not required in the digital optical detection.

Optionally, further modules can be introduced into the beam path in a known manner, for example additional lenses, filters, polarizers, incident-light illumination units and / or beam splitter systems.

The stereoscopic channels L and R are arranged here parallel to the central axis M. The distance B between the optical axes of the stereoscopic channels L and R is called a stereo base. The stereo base B defines the angle W at which each stereoscopic channel looks at the object. A diameter of a beam is with 39 designated. It depends on the position of the aperture stops 41 ,

The invention is neither on stereomicroscopes with differently shaped or by means of aperture stops 41 stereo channels L, R set to different numerical apertures, still generally limited to stereomicroscopes. The invention can also be used in particular in single-channel microscopes, as with reference to FIG 2 is illustrated. A "single-channel" microscope has a single beam path through the central lens 21 and, if available, a zoom system 30 with single-numbered optical units 31 to 33 respectively. 38 on. Single-channel microscopes are, for example, macroscopes and wide-field microscopes (epi microscopes), which can also benefit from the invention. Of course, the term "single-channel" does not exclude binocular or multichannel tubes or insights.

2 schematically shows a beam path of an optical channel of a microscope, which can be designed and / or operated according to the invention, in two apertures A and B. The optical channel may, for example, to one of the optical channels of a stereomicroscope or the beam path of a single-channel mentioned above Microscope, for example, a macroscope act. An appropriate one Beam path is in a stereomicroscope (see. 1 ) at least partially provided in pairs.

The optical marginal rays close due to the Apertureinstellung by means of the aperture stop 41 in the apertures designated A and B different angles θ a. The angle θ / 2 corresponds to the aperture angle σ between each one of the marginal rays and the optical axis 62 ,

The beam path includes the main objective 21 (in the classical microscope or macroscope usually only referred to as "objective"), as explained above. In an object plane 12 of the main objective 21 that corresponds to its front focal plane is an object to be viewed 11 arranged. A considered point is designated by a cross X. The main objective 21 is a zoom system 30 with three optical groups 31 to 33 downstream, as also explained.

Between the lens or optical group 38 and an optical group 53 the image capture unit 50 the beam path is also afocal here, but there is no coupling out of the portion of the light that is used for the image acquisition unit 50 is determined. Instead, as illustrated only in view A, a corresponding outcoupling of a share may occur 64 for visual observation by means of the eyepiece 96 respectively. For this example, mirror or prism surfaces 76 . 77 intended. The illustration is greatly simplified, in particular is a representation of a Bildaufrichtseinheit 92 has been dispensed with.

The diaphragm positions A and B correspond in the present example to the steps for the implementation of which a microscope system according to the invention can be set up. At a first time (corresponding to diaphragm position A, ie at a higher numerical aperture but at a lower depth of field), a first digital image acquisition takes place by means of the image acquisition unit 50 at a second time (corresponding to aperture B, ie at a lower numerical aperture but at a higher depth of field) a second.

In 3 is a relationship between resolution, numerical aperture and depth of field in the form of a diagram 300 illustrated. In the diagram 300 is a distance z to the focal plane of a lens, such as the main lens 21 , in mm on the abscissa and a resolution R in line pairs per millimeter on the ordinate. At a value z = 1 mm, a point is 1 mm above, at a value of -1 mm 1 mm below the focus plane.

As an example, resolution curves for numerical apertures nA of 0.1, 0.05 and 0.025 are shown, as are typical for stereomicroscopes, for example. As already mentioned, the resolution achieves a maximum at high numerical aperture, here of 300 line pairs per millimeter at a numerical aperture nA of 0.1. However, this maximum resolution decreases rapidly with increasing distance to the plane 0, the focus plane. Even at a distance of 0.1 mm, the resolution is only about one-sixth. This corresponds to the low depth of field explained above with a high numerical aperture.

The depth of field can be significantly improved if, for example, with an adjustable aperture stop 41 , the numerical aperture is reduced. The aperture stop is closed accordingly. As can be seen, for example, with a numerical aperture of 0.05 only half the maximum resolution compared to the numerical aperture of 0.1 results, but this is even better at a value z of 0.1 mm, ie outside the focal plane than at a numerical aperture of 0.1. To a greater extent, this applies to a further reduction of the numerical aperture to, for example, 0.025.

With the present invention, therefore, an image acquisition is sought in which ideally corresponds to the resolution of an envelope of the resolution curves shown. This can be done, for example, by means of in 4 illustrated steps 200 be achieved. In 4 are corresponding, implemented according to an embodiment of the invention in a microscope system steps in the form of a flowchart shown schematically.

First of all, there is a step 210 , For example, a microscope system set up for a corresponding method goes into the step 210 into an image capture mode. In one step 220 is, for example by means of a control computer 80 and / or by means of one in the image capture unit 50 integrated arithmetic unit or the like, given a number of images to be acquired. The number is denoted by n and stored in a counter i. The number n can be predetermined, for example, on the basis of the set magnification and / or of microscope parameters. At the same time in the step 220 also predefined a setting for an aperture adjustment (in the form of an adjustment step) and / or with respect to an exposure time and / or an amplification factor. This specification can also be made on the basis of currently set microscope parameters such as magnification and the like.

In one step 230 is done by outputting a corresponding signal to an aperture unit 40 an adjustment of the aperture diaphragm according to the predetermined adjustment step. The illustrated steps thus relate to a microscope system with a corresponding controllable aperture. In a subsequent step 240 the counter i is decremented by one. At the same time, a recording takes place by means of the image acquisition unit, which is stored in a buffer 241 is cached. As already explained above, in this case also recordings of, for example, two stereoscopic channels of a stereomicroscope can be made, which can also take place in particular successively. For example, first a stereoscopic channel can be hidden and a recording done. Subsequently, the selection of another stereoscopic channel and a corresponding recording takes place. Corresponding stereo image pairs can also be in the cache 241 be cached. Is the predetermined number of shots not yet reached, which by comparing in step 250 is determined again in step 230 an aperture adjustment in the manner explained and then a recording with decrementing the counter i.

After the predetermined number of shots has been taken, they are in one step 260 who also works in an external control computer 80 can be made, billed together. One cycle is in one step 270 terminated by, if not yet done, correspondingly charged images to an external control computer 80 or an external image display unit can be output. At the same time an adjustment of the aperture unit 40 in their ground state. This can again step to 210 be transferred.

In 5 the practical implementation of the measures according to the invention is illustrated in a microscope system designed as a stereomicroscope. The microscope system is in total with 1 designated.

The microscope system 1 includes a stage 10 , on its surface 13 an object 11 is arranged. A lens mount 20 for the main objective 21 is planned. The zoom systems 30 are in a housing 14 arranged, via appropriate adjustment means 15 , For example, to adjust filters and the like may have. For zooming the zoom systems 30 is an adjustment unit 16 intended. The adjustment unit 16 adjusts at least one movable optical group of the zoom systems 30 , To adjust the focus is an adjustment 17 intended. By means of the adjusting device 17 the stereomicroscope is at its height on a tripod 18 adjustable. The case 14 is on the image side of the tube 90 downstream, in the eyepieces 96 can be fitted. A digital imaging unit 50 , For example, a CCD camera, can be arranged in a beam path, for example, with the tube 90 can be disconnected.

The aperture unit 40 is completely inside the case 70 arranged, which does not change its outer dimensions. It can, as explained, by means of control signals of the digital image acquisition unit 50 be controlled. The microscope system 1 is set up to carry out the previously explained steps.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006036300 B4 [0009]
• DE 102006036768 B4 [0009]
• DE 102005040473 B4 [0052]
• US 6816321 A [0055]

Claims (12)

Microscope system ( 1 ) arranged to provide a digital result image and means (R, L, 41 ) for providing microscopic images at different numerical apertures and a digital image capture unit ( 50 ), characterized in that the image capture unit ( 50 ) is adapted to capture at least two microscopic images at different numerical apertures in the form of digital frames and each corresponding image areas of the digital frames with respect to their sharpness to each other, each composed the image areas of the digital frames with the highest image sharpness to the digital result image become. Microscope system ( 1 ) according to claim 1, wherein the image capture unit ( 50 ) for comparing the different image areas of the digital frames with respect to their image sharpness using at least one value characterizing the sharpness of the image. Microscope system ( 1 ) according to claim 1 or 2, wherein the image capture unit ( 50 ) is arranged to set the mutually corresponding image areas of the digital frames based on a predetermined position in the at least two digital frames. Microscope system ( 1 ) according to claim 3, wherein the image capture unit ( 50 ) is set up to define the predetermined position in the form of identical image coordinates and / or identical pixel regions in the at least two digital individual images. Microscope system ( 1 ) according to one of the preceding claims, in which the image capture unit ( 50 ) is adapted to determine the mutually corresponding image areas of the digital frames based on an image content detection. Microscope system ( 1 ) according to one of the preceding claims, in which the image capture unit ( 50 ) is arranged to detect the at least two microscopic images and the comparison of the corresponding image areas for at least two different focus settings of a main objective ( 21 ) of the microscope system ( 1 ), so that in each case a result image is obtained for the at least two different focus settings. Microscope system ( 1 ) according to one of the preceding claims, in which the means (L, R, 41 ) for providing the microscopic images at the different numerical apertures at least one optical channel (L, R) with an aperture stop ( 41 ) with adjustable aperture. Microscope system ( 1 ) according to one of Claims 1 to 8, in which the means (L, R) for providing the microscopic images at the different numerical apertures comprise two optical channels (L, R) with different and / or adjustable numerical apertures. Microscope system ( 1 ) according to claim 8, wherein the image capture unit ( 50 ) is adapted to simultaneously provide and detect the at least two microscopic individual images at the different numerical apertures by means of two optical channels (L, R) each having a fixed numerical aperture. Microscope system ( 1 ) according to claim 7, comprising a control device ( 80 ), which is adapted to the digital image acquisition unit ( 50 ) such that the digital image acquisition unit ( 50 ) at least two digital frames at different apertures of the aperture diaphragm ( 41 ) in the at least one optical channel (L, R) detected. Microscope system ( 1 ) according to claim 10, wherein the control device ( 80 ) is set up, in each case a number of digital frames to be acquired and an adjustment amount for the aperture diaphragm ( 41 ) in the at least one optical channel (L, R) and alternately a detection of the digital frames by means of the digital image capture device ( 50 ) and an adjustment of the aperture diaphragm ( 41 ) to carry out the adjustment. Microscope system ( 1 ) according to one of the preceding claims, which is designed as a stereomicroscope with two stereoscopic channels (L, R), each of the stereoscopic channels each having a detection module ( 52 ) of the digital image capture unit ( 50 ) assigned.

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