Apparatus and method for imaging an object

Abstract

An optical imaging device for a microscope is provided, comprising an objective lens configured to collect detection light from an object and direct the detection light into an optical path, and an optical system comprising a plurality of lens elements configured to interact with the objective lens to selectively optically image the object in a first operating mode and a second operating mode. The optical system comprises a first optical subsystem associated with the first operating mode configured to form a first image of the object at a first magnification. The optical system comprises a second optical subsystem associated with the second operating mode configured to form a second image of the object at a second magnification, the second magnification being less than the first magnification. The second optical subsystem comprises an optical module insertable into the optical path for selecting the second operating mode. The optical module comprises a lens element having a positive refractive power, which when inserted into the optical path makes the second magnification less than the first magnification by being closer to an exit pupil of the objective lens than other lens elements of the optical system.

Description

Technical Field

[0001] The invention relates to an optical imaging device for a microscope, comprising an objective lens configured to collect detection light from an object and to focus said detection light into an optical path. Furthermore, the invention relates to a method for imaging an object. Background Art

[0002] Finding an object to image through a microscope can be a difficult task. Especially in microscope systems where objective changes are not possible or have severe limitations, finding an object can be a significant challenge. This is especially the case when using immersion objectives with long working distances in an inverted microscope configuration. Even when using an automated immersion dispenser, there is a risk that applying or removing the immersion medium will destroy the correlation between imaging situations using different objectives.

[0003] When using microscope systems with relatively high magnification and high numerical aperture, the lateral dimensions of the object field to be imaged and the axial depth of field are relatively small. In particular, in order to enlarge the object field, it is therefore necessary to switch to a different objective with lower magnification and lower numerical aperture. However, changing objectives entails serious disadvantages, especially when using immersion-based microscope systems, for the reasons mentioned above.

[0004] The situation becomes more complicated when using microscopes with imaging configurations that deviate from the usual configuration of focusing on an object plane parallel to the microscope stage surface. For example, recent light sheet microscopy techniques such as oblique plane microscopy (OPM) have been developed in which the imaged object plane is tilted relative to the surface of the sample carrier. This tilting of the object plane enables illumination and detection through the transparent bottom of the sample carrier, according to the geometry in which the illumination light and the detection propagate orthogonally to each other.

[0005] Conventional microscope tubes may include an image inversion magnification changer, allowing the numerical aperture to be reduced when imaging the object. However, the object field imaged by these tube systems is relatively small. In particular, the object field is too small to image the complete microtiter cavity of a well plate, such a cavity having a lateral dimension of the order of several millimeters. Furthermore, in order to find the object along the optical axis, object-side focusing is necessary. Such object-side focusing creates problems in inverted microscope systems including immersion objectives with large working distances. As a result, it may be difficult to retain the immersion medium as desired in the space between the sample and the objective front lens when performing object focusing. Summary of the invention

[0006] The object of the present invention is to provide an optical imaging device for a microscope and a method which make it easier to find an object in order to subsequently form an optical image of the object.

[0007] The above objects are achieved by the subject-matter of the independent claims. Advantageous embodiments are defined in the dependent claims and in the following description.

[0008] The optical imaging device includes an objective lens configured to collect detection light from an object and guide the detection light into an optical path, and an optical system including a plurality of lens elements configured to interact with the objective lens for selectively optically imaging the object in a first operating mode and a second operating mode. The optical system includes a first optical subsystem associated with the first operating mode, the first optical subsystem being configured to form a first image of the object at a first magnification. The optical system includes a second optical subsystem associated with the second operating mode, the second optical subsystem being configured to form a second image of the object at a second magnification. The second magnification is less than the first magnification. The second optical subsystem includes an optical module that can be inserted into the optical path for selecting the second operating mode. The optical module includes a lens element having a positive refractive power, the lens element having a positive refractive power, when inserted into the optical path, making the second magnification less than the first magnification by being closer to an exit pupil of the objective lens than other lens elements of the optical system.

[0009] The optical imaging device provides two different operating states for imaging an object at two different magnifications. In particular, a first operating mode can be used to provide a high-magnification close-up image of a region of interest (ROI) that has been found before the actual image acquisition. In order to find this ROI, a second operating mode can be used to provide a low-magnification overview image in which the ROI is included. Thus, the optical imaging device enables a user to find the object to be imaged more easily. In particular, the user is not forced to change the objective lens. This is particularly advantageous when using an immersion-based microscope system, because no immersion medium needs to be provided or removed when acquiring images with low and high magnifications. Therefore, the imaging situation does not change fundamentally and the two images can be easily correlated with each other.

[0010] Avoiding objective changes is particularly advantageous in configurations that deviate from the usual imaging configuration, where the optical system focuses onto a plane parallel to the microscope stage surface. For example, the optical imaging apparatus can be advantageously used in light sheet microscopy, such as OPM, where the optical system focuses onto an object plane that is tilted relative to the microscope stage surface, because illumination and detection need to be orthogonal to each other.

[0011] Furthermore, the optical imaging device is particularly suitable for imaging a complete microtiter chamber of a well plate comprising a plurality of such chambers. Thus, in a first step, a specific chamber can be imaged in its entirety by applying a second operating mode based on a lower magnification for performing image acquisition. Subsequently, in a second step, the chamber thus found can be examined in detail by applying the first operating mode based on a higher magnification.

[0012] Switching between the first and second operating modes is achieved by selectively inserting an optical module into the optical path, the optical module being part of a second optical subsystem associated with the second operating mode. In other words, when the optical module is inserted into the optical path, the second operating mode is selected. Conversely, when the optical module is retracted from the optical path, the first operating mode is selected. Thus, by controlling the optical module, a user can easily switch between the two modes.

[0013] In order to produce a large object field to be imaged in the second operating mode, the optical module includes a lens element with positive refractive power. When the optical module is inserted into the light path, this positive lens element is closer to the exit pupil of the objective lens than other lens elements of the optical system. The positive lens element of the optical module is arranged at a position close to the exit pupil of the objective lens, which can ensure that the detection light is collected by the positive lens element at a position where the field angle of the detection light is moderate, that is, not too large. Therefore, the size of the optical element can be limited, thereby making the optical imaging device compact. In particular, it is not necessary to provide a high numerical aperture objective lens with a particularly long focal length to achieve a large object field, and such an objective lens is very expensive. In contrast, the optical imaging device claimed for protection allows the use of an objective lens with a high numerical aperture and corrected for an infinite optical tube length, wherein the objective lens can have a medium focal length, which is advantageous in terms of compactness and cost.

[0014] The imaging device may include a suitable mechanism for inserting the optical module into the optical path and removing it therefrom. For example, an electric actuator may be provided for rotating the module.

[0015] Preferably, the optical module further comprises an optical deflector, the optical deflector being configured to branch an optical side path from the optical path when inserted into the optical path, the second image being formed in the optical side path. The aforementioned optical side path can be used as a separate optical path in the second operating mode for creating an overview image that enables a user to find different objects, such as a specific microtiter cavity of a well plate, or a specific region of interest (ROI) of a larger object. Conversely, the optical path that is effective in the first operating mode can be used to create a close-up image of an object determined in the first operating mode.

[0016] In a preferred embodiment, the second optical subsystem comprises a Keplerian telescope system having a first lens element closest to the object side formed by said lens element having positive refractive power included in the optical module. Thus, by switching the optical module into the optical path, a telescope system is created that can be used to form an overview image. In particular, when the optical module is switched into the optical path, the first optical subsystem remains unchanged. Since the first optical subsystem operates at a higher magnification to achieve high-quality imaging, it is more sensitive to any adjustments than the second optical subsystem. Therefore, it is advantageous to keep the first optical subsystem substantially unchanged when switching between operating states. Therefore, the optical imaging device is switched using a movable optical module of the second optical subsystem.

[0017] The Keplerian telescope system can be configured to form an image of the exit pupil. By using such a telescope with an afocal optical system with a real intermediate pupil, many options are provided for integrating additional optical components into the microscope. For example, components for implementing radiofluorescence illumination can be integrated. Furthermore, phase filters for implementing contrast methods can be integrated.

[0018] In particular, the second optical subsystem may comprise an aperture stop located in the position of said image of the exit pupil, said image being formed as a real image.

[0019] The Keplerian telescope system may include a second lens element having a positive refractive power, which is configured to collimate beams of detection light, each beam being associated with a single point of an object field from which the objective lens collects the detection light. In a particular embodiment, a field lens may additionally be provided between the first positive lens element and the second positive lens element of the telescope system.

[0020] The Keplerian telescope system consisting of the two positive lens elements described above serves to scale the focal length of the objective by a factor given by the afocal factor of the telescope system. Furthermore, the Keplerian telescope system serves to form a real image of the exit pupil of the objective. Since it can be expected that vignetting cannot be avoided in the objective, the aperture stop serves to reduce the imaged exit pupil. Thus, the aperture stop serves to achieve a certain homogenization of the light path within the second optical subsystem.

[0021] In particular, the Keplerian telescope system will be considered as a reduced-magnification system associated with the normal use of an objective lens in relation to a tube lens having a reference focal length. Therefore, the magnification of the objective lens must be related to the nominal focal length of the tube lens. Assuming the focal length of the tube lens is 200 mm and the focal length of the objective lens is 10 mm, the magnification of the objective lens is 20. Further, assuming that the afocal factor of the Keplerian telescope system is 4, the magnification of the objective lens is effectively reduced from 20 to 20 / 4, or 5.

[0022] The second optical subsystem may comprise an image sensor located in said image plane.The image sensor may be formed, for example, by a CCD or CMOS camera.

[0023] Preferably, at least one of the lens elements of the second optical subsystem is configured to correct residual aberrations of said lens element having positive refractive power included in the optical module. According to this embodiment, in the case where a fully corrected intermediate image is not provided in the Kepler telescope system, the first positive lens element of the telescope system, i.e. the positive lens element included in the optical module, is designed to be as simple as possible to reduce its size, and the correction of aberrations is achieved by the remainder of the second optical subsystem, for example by the second positive lens element and / or the tube lens of the Kepler telescope system.

[0024] The tube lens can be formed by an optical system similar to an objective lens with a low magnification. Preferably, the second magnification is in the range of 1.0 to 2.5. In addition, the second magnification can be determined to be substantially equal to the ratio of the object side refractive index to the image side refractive index. In the case of undersampling, that is, when the image side aperture of the amplification optical path associated with the second optical subsystem is not fully sampled, the matching of the refractive index ratio does not need to be very accurate. In this case, the aberrations will be moderate and image side focusing can be provided, for example by moving the image sensor of the second optical subsystem along the optical axis. By applying image side focusing instead of object side focusing, problems that may occur when focusing an immersion objective lens with a large working distance in an inverted microscope system can be avoided. Therefore, in a preferred embodiment, the second optical system is configured to perform image side focusing on the object.

[0025] The second optical subsystem may further be configured to perform image-side focusing such that the object-side defocus of 5 mm compensated by the image-side focusing causes one pixel of the image sensor included in the second optical subsystem to receive a predetermined integrated light intensity that is not less than 50% of the integrated reference light intensity received by the pixel in a nominal focus state of the second optical system, i.e., in a state without object-side or image-side defocus. Thus, effective image-side defocus may be achieved taking into account any undersampling.

[0026] Preferably, the objective is formed by an immersion objective.As mentioned above, the optical imaging device allows to avoid any modification of the objective, which is particularly advantageous when using an immersion based system.

[0027] Since the objective is used in both operating states, according to a preferred embodiment a dispenser may be provided for supplying immersion medium to the objective.

[0028] Preferably, the optical imaging device satisfies at least one of the following conditions:

[0029] (1) f≤=30 mm;

[0030] (2) NA ≥ = 0.8;

[0031] (3) FAA ≥ 1 mm;

[0032] (4) d ≤ 30 mm;

[0033] (5)D>4.5mm;

[0034] in

[0035] f represents the focal length of the objective lens;

[0036] NA represents the full numerical aperture of the objective lens in the second operating mode;

[0037] FAA stands for Free Operating Range;

[0038] d represents the distance from the lens element having positive refractive power to the image side end of the objective lens; and

[0039] D denotes the diameter of the object field from which the objective lens collects the detection light.

[0040] According to another aspect, a microscope is provided comprising an optical imaging device as described above. The invention can be applied to any type of microscope, such as widefield microscopes, confocal microscopes, multiphoton microscopes and light sheet microscopes, in particular in OPM or SCAPE configurations.

[0041] According to another aspect, a method for imaging an object is provided, comprising the steps of collecting detection light from the object and focusing the detection light into an optical path through an objective lens; and selectively imaging the object in a first operating mode and a second operating mode through an optical system including a plurality of lens elements interacting with the objective lens. A first image of the object is formed at a first magnification in the first operating mode. A second image of the object is formed at a second magnification in the second operating mode. The second magnification is less than the first magnification. An optical module is inserted into the optical path for selecting the second operating mode. The optical module includes a lens element having a positive refractive power, and when inserted into the optical path, the second magnification is less than the first magnification by being closer to an exit pupil of the objective lens than another lens element of the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The specific embodiments are described below in conjunction with the accompanying drawings, wherein:

[0043] Figure 1 is a schematic diagram showing a microscope according to the embodiment. DETAILED DESCRIPTION

[0044] Figure 1A microscope 100 is shown including an optical imaging device 102 configured to form an optical image of an object 104. Note that Figure 1 Only those features of the microscope 100 that may be helpful in understanding the principles of operation of the optical imaging device 102 as part of the microscope 100 are described. The microscope 100 may include Figure 1 Additional components not shown.

[0045] The imaging device 102 includes an objective lens 106 facing an object 104 located at Figure 1 Furthermore, the imaging device 102 comprises an optical system 108, which comprises first and second optical subsystems 110, 112, which will be described in more detail below.

[0046] The objective lens 106 is used to collect detection light from the object 104 and focus the detection light into the optical path 114. Specifically, the objective lens 106 captures the detection light from the object field 116, which is located in the object plane coinciding with the object-side focal plane of the objective lens 106. Therefore, the objective lens 106 interacts with the optical system 108 to form an optical image of the object field 116.

[0047] Objective lens 106 may be a lens commonly used for illumination and detection. Figure 1 1 , the microscope 100 includes additional optical components, not shown, which are configured to feed light to the objective 106 to illuminate the object 102. Alternatively or additionally, the microscope 100 may include a separate optical device for illuminating the object 104.

[0048] The optical imaging device 102 provides two different operating modes, a first mode associated with a first optical subsystem 110 and a second mode associated with a second optical subsystem 112. In particular, the first optical subsystem 110 is used to form a first optical image of the object 104 with a first magnification in the first operating mode. Similarly, the second optical subsystem 112 is used to form a second optical image of the object 104 with a second magnification in the second operating mode, wherein the second magnification is smaller than the first magnification. Providing different operating modes with different magnifications enables the user to, for example, acquire a low-magnification overview image (corresponding to the aforementioned second image) in a first step in order to find a suitable ROI within the object 104, which will be imaged later. After finding the ROI, a high-magnification image of the ROI (corresponding to the aforementioned first image) is acquired in a second step. In other words, the object field 116 imaged in the second operating mode is larger than the object field 116 imaged in the first operating mode. Therefore, when switching the magnification based on the image acquisition to be performed, the user does not need to change the objective lens 106.

[0049] according to Figure 1In the particular embodiment shown, the first optical subsystem 110 associated with the first operating mode is formed by lens elements commonly used in wide-angle microscopes. These lens elements may, for example, include a tube lens 120 that focuses the image produced by the objective lens 106 onto an image plane 122. The first optical subsystem 110 is formed by lens elements commonly used in wide-angle microscopes. Figure 1 , and the first optical subsystem 110 may include Figure 1 104. Additional optical components not shown in the drawings may be provided. For example, further lens elements may be provided to optically transmit the intermediate image produced by the objective lens 106 in the image plane 122 to the image sensor. Alternatively, the image sensor may be provided directly in the image plane 122. In any case, it should be noted that any other optical configuration may be applied, which is suitable for cooperating with the objective lens 106 to optically image the object 104. Also, a scanning device (e.g. a confocal scanner or a multiphoton scanning device) may be used to scan the image plane 122.

[0050] The second optical subsystem 112 associated with the second operating mode includes an optical module 118 that is selectively insertable into the optical path 114. To this end, the optical module 118 can be formed of a rotatable optical component, and the microscope 100 can include a suitable mechanism configured to rotate the optical module 118 into the optical path 114 and retract it therefrom to switch between the first and second operating modes.

[0051] The optical module 118 includes a lens element 126 having a positive refractive power. In addition, the optical module 118 may include a light deflector 128 formed, for example, by a mirror. Since they are integrated in the optical module 118, the lens element 126 and the light deflector 128 may be integrally rotated into the optical path 114 and may be retracted therefrom when the optical module 118 is moved accordingly to selectively switch between the first and second operating modes.

[0052] In the first operating mode, the optical module 118 is retracted from the optical path 114. Therefore, the second optical subsystem 112 is switched to an inactive state, and the first optical subsystem 110 is used for image acquisition in the first operating mode. To this end, the first optical subsystem 110 interacts with the objective lens 106 to form a first image according to a first magnification. In particular, according to Figure 1 A first image is created in the image plane 122. As described above, the first image may be a high magnification close-up image of the selected ROI.

[0053] In the second operating mode, the optical module 118 is inserted into the optical path 114. Accordingly, the light deflector 128 prevents the detection light propagating along the optical path 114 from being transmitted to the first optical subsystem 110, and the first optical subsystem 110 is switched to an inactive state. Instead, the second optical subsystem 112 is switched to an active state in the second operation, where the second optical subsystem 112 interacts with the objective lens 106 to create a second optical image according to the second magnification. As described above, the second magnification is less than the first magnification applied in the first operating mode, and the second image can be a low-magnification overview image for finding a suitable ROI.

[0054] From Figure 1 It can be seen that in the case where the optical module 118 is inserted into the optical path 114, the lens element 126 integrated with the optical module 118 is closer to the objective lens 106 than any other lens element included in the optical system 108. As described above, the optical system 108 includes a first optical subsystem 110 and a second optical subsystem 112 associated with the first and second operating modes, respectively. In particular, the lens element 126 is positioned as close as possible to the exit pupil 130 of the objective lens 106. According to Figure 1 the specific embodiment shown, the exit pupil 130 is located within the housing 132 of the objective lens 106. Accordingly, the lens element 126 of the optical module 118 is positioned as close as possible to the end face 134 of the housing 132, possibly taking into account any focusing movement of the objective lens 106 relative to the object 104 and changing the distance between the end face 134 of the housing 132 and the lens element 126.

[0055] Since the positive lens element 126 is located at a short axial distance from the exit pupil 130 of the objective lens 106, the detection light is collected by the lens element 126 at a position where the lateral expansion of the light beam caused by the large field of view angle of the detection light is relatively small. Accordingly, the lens element 126 can be made smaller. In particular, it is not necessary to use a high numerical aperture objective lens with a large focal length, such a large focal length making the microscope objective very expensive.

[0056] As Figure 1 is visible, the light deflector 128 branches off a light side path 136 from the optical path 114 leading from the exit pupil 130 of the objective lens 106 to the light deflector 128. The light side path 136 can be considered an optical overview path used in the second operating mode for creating a low-magnification overview image based on which a suitable ROI can be found. Instead, in the case where the light side path 136 is not branched off, the optical path 114 as a whole can be considered the main optical path for creating a high-magnification close-up image of the selected ROI in the first operating mode.

[0057] According to Figure 1In the particular embodiment shown, the second optical subsystem 112 includes a Keplerian telescope system 138, which includes two lens elements, each lens element having a positive refractive power. The first of the two lens elements is formed by a lens element 126 that is part of the optical module 118. The second lens element of the telescope system 138 is formed by an element 140 that is located downstream of the lens element 126 along the optical path 136. In other words, when the optical module 118 is inserted into the optical path 114, the lens elements 126 and 140 combine to form the Keplerian telescope system 138, which is switched to an active state in the second operating mode.

[0058] The Keplerian telescope system 138 is configured to form a real image 142 of the exit pupil 130 of the objective lens 106 in the optical side path 136. Specifically, the real image 142 of the exit pupil 130 is generated downstream of the second lens element 140 of the Keplerian telescope system 138. An aperture stop 144 may be disposed at a position of the real image 142 of the exit pupil 130. In addition, along the optical side path 136 downstream of the aperture stop 144, the second optical subsystem 112 may include a tube lens 146 and an image sensor 148. The tube lens 146 is configured to focus the detection light propagating through the optical side path 136 onto the image sensor 148, thereby forming a second image based on a second magnification.

[0059] The second optical element 140 of the Keplerian telescope system 138 collimates the detection light passing therethrough, each beam of the detection light being associated with a single point of the object field 116. In this regard, it is noted that the Keplerian telescope system 138 may further include Figure 1 A field lens not shown in the figure is located between the two positive lens elements 126 and 140.

[0060] The aforementioned aperture stop 144 can be used to reduce the exit pupil 130 of the image formed by the objective lens 106. Therefore, the adverse effects caused by vignetting or aberration that occur in an objective lens with a large field angle and a high numerical aperture can be prevented from appearing in the light side path 136.

[0061] according to Figure 1 In the illustrated embodiment, the aberrations of the second positive lens element and / or the tube lens 146 of the Keplerian telescope system 138 may be corrected instead of the positive lens element 126 that is integrated into the optical module 118 and forms the first lens of the Keplerian telescope system 138. Thus, the correction lens elements 138, 146 are used to correct the residual aberrations caused by the positive lens element 126 of the optical module 118.

[0062] Figure 1The illustrated configuration provides an additional infinite optical path between the Keplerian telescope system 138 and the tube lens 146, which includes a real center pupil in the form of a real image 142 of the exit pupil 130. The additional infinite optical path can be used to integrate additional optical components into the microscope 100, such as components for epi-fluorescence illumination, phase filters, phase modulators, etc.

[0063] In this regard, it is noted that the optical path 114 leading from the objective lens 106 to the first optical subsystem 110 also forms an infinite optical path. However, this infinite optical path is (at least partially) associated with both the first and second operating modes. Therefore, it should not be used to incorporate optical components specifically determined to perform the second operating mode.

[0064] By way of example only, objective lens 106 may be characterized by parameters as specified in conditions (1) to (5) above. Figure 1 , the working distance FAA of condition (3) represents the distance from the object side front end of the objective lens 106 to the object field 116, the distance d of condition (4) represents the distance from the lens element 126 to the end face 135 of the objective lens 106, and the diameter D of condition (5) represents the diameter of the object field 116 perpendicular to the optical axis direction. It should be noted that the diameter D refers to the object field 116 imaged in the second operation mode. From the above, it can be understood that the object field 116 associated with the second operation mode is larger than the object field associated with the first operation mode.

[0065] According to an existing embodiment, the second magnification applied in the second operating mode can be in the range of from 1.0 to 2.5. Due to the above reasons, image side focusing can be applied instead of object side focusing. To this end, the image sensor 148 can be moved along the optical axis direction to achieve focusing. In an alternative embodiment of image side focusing, the image sensor 148 remains fixed and the tube lens 146 moves along the optical axis.

[0066] In the case where the objective lens 106 is formed by an immersion objective lens, it is particularly advantageous to apply image side focusing. Therefore, when using image side focusing instead of object side focusing, any axial movement between the object 104 and the objective lens 106 can be avoided. Therefore, the immersion medium 150 located between the object 104 and the objective lens 106 is always not affected by the focusing. In the case of using an immersion objective lens, the imaging device 102 can include a dispenser 152, which supplies the immersion medium 150 to the space between the object 104 and the front end of the objective lens 106.

[0067] It should be noted that the present invention should not be limited to the above-described embodiments. In particular, any type of microscope can be used to achieve image acquisition with two different magnifications that are switched by inserting an optical module comprising a positive lens element close to the exit pupil of the objective. For example, a light sheet microscope can be used, such as in an OPM or SCAPE configuration.

[0068] Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of a corresponding method, where a block or device corresponds to a method step or a feature of a method step. Similarly, the aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware device, such as a processor, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some of the most important method steps may be performed by such a device.

[0069] Depending on certain implementation requirements, embodiments of the present invention may be implemented in hardware or software. The implementation may be performed using a non-temporary storage medium, such as a digital storage medium, e.g., a floppy disk, DVD, Blu-ray, CD, ROM, PROM and EPROM, EEPROM or FLASH memory, on which electronically readable control signals are stored that cooperate (or are capable of cooperating) with a programmable computer system to perform the corresponding method. Thus, the digital storage medium may be computer readable.

[0070] Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.

[0071] Generally, embodiments of the present invention can be implemented as a computer program product with a program code, when the computer program product runs on a computer, the program code is operative for performing one of the methods.For example, the program code can be stored on a machine readable carrier.

[0072] Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier.

[0073] In other words, therefore, an embodiment of the inventive method is a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

[0074] A further embodiment of the invention is therefore a storage medium (or a data carrier, or a computer-readable medium) comprising a computer program stored thereon for performing one of the methods described herein when executed by a processor. The data carrier, the digital storage medium or the recorded medium is typically tangible and / or non-transitory. A further embodiment of the invention is an apparatus as described herein, comprising a processor and a storage medium.

[0075] A further embodiment of the invention is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein.The data stream or the sequence of signals may, for example, be configured to be transmitted via a data communication connection, for example via the Internet.

[0076] A further embodiment comprises a processing means, for example a computer or a programmable logic device, configured to or adapted to perform one of the methods described herein.

[0077] A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

[0078] A further embodiment according to the invention comprises an apparatus or system configured to transmit (e.g. electronically or optically) a computer program for performing one of the methods described herein to a receiver. For example, the receiver may be a computer, a mobile device, a memory device, etc. For example, the apparatus or system may comprise a file server for transmitting the computer program to the receiver.

[0079] In some embodiments, a programmable logic device (e.g., a field programmable gate array) can be used to perform some or all functions of the methods described herein. In some embodiments, a field programmable gate array can collaborate with a microprocessor to perform one of the methods described herein. Typically, these methods are preferably performed by any hardware device.

[0080] Reference numerals list

[0081] 100 Microscope

[0082] 102 Optical imaging equipment

[0083] 104 Objects

[0084] 106 Objective

[0085] 108 Optical System

[0086] 110 First optical subsystem

[0087] 112 Second optical subsystem

[0088] 114 Light Path

[0089] 116 Material Field

[0090] 118 Optical Module

[0091] 120 Tube lens

[0092] 122 Image plane

[0093] 126 Lens elements with positive refractive power

[0094] 128 Light Deflector

[0095] 130 Exit pupil

[0096] 132 Housing

[0097] 134 End face

[0098] 136 Guang Side Road

[0099] 138 Kepler Telescope System

[0100] 140 lens elements

[0101] 142 True Image of Exit Pupil

[0102] 144 Aperture stop

[0103] 146 Tube lens

[0104] 148 Image Sensor

[0105] 150 Immersion medium

[0106] 152 Distributor

Claims

1. An optical imaging device (102) for a microscope (100), include: an objective lens (106) configured to collect detection light from the object (104) and direct the detection light into an optical path (114), and an optical system (108) comprising a plurality of lens elements configured to interact with the objective lens (106) for selectively optically imaging the object (104) in a first operating mode and a second operating mode, wherein the optical system (108) includes a first optical subsystem (110) associated with the first operating mode, the first optical subsystem being configured to form a first image of the object (104) at a first magnification, wherein the optical system (108) includes a second optical subsystem (112) associated with the second operating mode, the second optical subsystem (112) being configured to form a second image of the object (104) at a second magnification, the second magnification being less than the first magnification, wherein the second optical subsystem (112) comprises an optical module (118) insertable into the optical path (114) for selecting the second operation mode, the optical module (118) comprising a lens element (126) having a positive refractive power, the lens element (126) having a positive refractive power, when inserted into the optical path (114), being closer to an exit pupil (130) of the objective lens (106) than other lens elements of the optical system (108), so that the second magnification is smaller than the first magnification; The optical module further comprises a light deflector (128), the light deflector (128) being configured to branch a light side path (136) from the light path (114) when inserted into the light path (114), the second image being formed in the light side path (136); wherein the second optical subsystem (112) includes a Kepler telescope system (138), the Kepler telescope system (138) having a first lens element closest to the object side formed by the lens element (126) having positive refractive power included in the optical module (118); wherein the Keplerian telescope system (138) is configured to form an image (142) of the exit pupil (130); The second optical subsystem (112) includes an aperture stop (144), the aperture stop (144) is located at the position of the image (142) of the exit pupil (130), and the image (142) is formed as a real image.

2. The optical imaging device (102) according to claim 1, in, The Keplerian telescope system (138) includes a second lens element (140) having a positive refractive power, the second lens element (140) being configured to collimate beams of the detection light, each beam being associated with a single point in the object field (116) from which the objective lens (106) collects the detection light.

3. The optical imaging device (102) according to claim 1 or 2, in, The second optical subsystem (112) includes a tube lens (146) configured to focus the detection light onto an image plane.

4. The optical imaging device (102) according to claim 3, in, The second optical subsystem (112) includes an image sensor (148) located in the image plane.

5. The optical imaging device (102) according to claim 2, in, At least one of the second lens element (140) and the tube lens (146) of the second optical subsystem (112) is configured to correct residual aberrations of the lens element (126) having positive refractive power included in the optical module (118).

6. The optical imaging device (102) according to claim 1 or 2, in, The second magnification is in the range from 1.0 to 2.

5.

7. The optical imaging device (102) according to claim 1 or 2, in, The second magnification is equal to the ratio of the object side refractive index to the image side refractive index.

8. The optical imaging device (102) according to claim 1 or 2, in, The second optical subsystem (112) is configured to perform image-side focusing on the object (104).

9. The optical imaging device (102) according to claim 8, in, The second optical subsystem (112) is configured to perform the image-side focusing so that the object-side defocus of 5 mm compensated by the image-side focusing causes a predetermined integrated light intensity to be received by a pixel of the image sensor (148) included in the second optical subsystem (112), and the predetermined integrated light intensity is not less than 50% of the integrated reference light intensity received by the pixel in a nominal focus state of the second optical subsystem (112).

10. The optical imaging device (102) according to claim 1 or 2, in, The objective lens (106) is formed by an immersion objective lens.

11. The optical imaging device (102) according to claim 10, comprising a dispenser (152) configured to supply an immersion medium (150) to the objective lens (106).

12. The optical imaging device (102) according to claim 1 or 2, wherein at least one of the following conditions is satisfied: (1) f ≤ 30 mm; (2) NA ≥ 0.8; (3)FAA ≥ 1 mm; (4) d ≤ 30 mm; (5)D > 4.5 mm; in f represents the focal length of the objective lens (106); NA represents the full numerical aperture of the objective lens (106) in the second operating mode; FAA stands for Free Operating Range; d represents the distance from the lens element (126) having positive refractive power to the image side end of the objective lens (106); as well as D denotes the diameter of the object field (116) from which the objective lens (106) collects the detection light in the second operating mode.

13. A microscope (100) comprising the optical imaging device (102) according to any one of claims 1-12.

14. A method for imaging an object (104), The following steps are involved: collecting detection light from the object (104) and focusing the detection light into the optical path (114) through the objective lens (106), and selectively imaging the object (104) in a first operating mode and a second operating mode by an optical system (108) including a plurality of lens elements interacting with the objective lens (106), wherein in the first operating mode a first image of the object (104) is formed at a first magnification, wherein in the second operating mode a second image of the object (104) is formed at a second magnification, the second magnification being smaller than the first magnification, wherein an optical module (118) is inserted into the optical path (114) for selecting the second operation mode, the optical module (118) comprising a lens element (126) having a positive refractive power, the lens element (126) having a positive refractive power, when inserted into the optical path (114), being closer to an exit pupil (130) of the objective lens (106) than other lens elements of the optical system (108), so that the second magnification is smaller than the first magnification; The optical module further comprises a light deflector (128), the light deflector (128) being configured to branch a light side path (136) from the light path (114) when inserted into the light path (114), the second image being formed in the light side path (136); The optical system (108) includes a Kepler telescope system (138), wherein the Kepler telescope system (138) has a first lens element closest to the object side formed by the lens element (126) having positive refractive power included in the optical module (118); wherein the Keplerian telescope system (138) is configured to form an image (142) of the exit pupil (130); The optical system (108) comprises an aperture stop (144), the aperture stop (144) being located at the position of the image (142) of the exit pupil (130), the image (142) being formed as a real image.

Images