阅读说明：本技术 微球透镜组件 (Microsphere lens assembly ) 是由 索林·斯特内斯库 塞巴斯蒂安·维拉 吴敬慈 李琳 于 2018-06-28 设计创作，主要内容包括：微球透镜组件(10)包括微球透镜(1)和基础透镜(3),其二者通过光学透明材料(2)形成的柱体连接在一起,所述光学透明材料(2)形成的柱体将微球透镜(1)相对于基础透镜(3)保持在固定位置上。当微球透镜(1)相对于基础透镜(3)固定在正确的位置上时,可以结合合适的显微镜来使用组件(10),用于进行超分辨率显微和/或加工。(The microsphere lens assembly (10) comprises a microsphere lens (1) and a base lens (3) which are connected together by a column of optically transparent material (2), the column of optically transparent material (2) holding the microsphere lens (1) in a fixed position relative to the base lens (3). When the microsphere lens (1) is fixed in the correct position with respect to the base lens (3), the assembly (10) can be used in conjunction with a suitable microscope for super-resolution microscopy and/or machining.)

1. A microsphere lens assembly, comprising: a base lens; a microsphere lens and a cylinder formed of an optically transparent material extending from the front surface of the base lens to the microsphere lens.

2. The microsphere lens assembly of claim 1, wherein the microsphere lens comprises a microsphere.

3. The microsphere lens assembly of claim 1, wherein the microsphere lens comprises an array of microspheres.

4. The microsphere lens assembly of claim 1, wherein the microsphere lens comprises truncated microspheres.

5. The microsphere lens assembly of claim 1, wherein the microsphere lens comprises an array of truncated microspheres.

6. The microsphere lens assembly of any preceding claim, wherein the optically transparent material comprises glass or plastic.

7. The microsphere lens assembly of any one of the preceding claims, wherein the optically transparent material comprises an adhesive or a resin and the optically transparent material is UV light curable.

8. The microsphere lens assembly of any one of the preceding claims, wherein the post extends from an edge of the base lens to an edge of the microsphere lens.

9. A method of constructing a microsphere lens assembly, comprising the steps of: attaching a base lens to a microscope; providing a microsphere lens on a sample; applying an optically clear and UV light curable material between the base lens and the microsphere lenses; adjusting the spacing between the microsphere lens and the base lens until the microsphere lens is centered in the field of view of the base lens and the sample is in focus; illuminating the back side of the base lens with UV light; and separating the base lens from the sample.

10. The method of claim 9, wherein the sample is a known sample or a specialized calibration sample.

11. A method according to claim 9 or 10, characterized in that the method comprises the step of cleaning off excess optically transparent material after illuminating the back surface of the base lens with UV light.

12. A method according to claim 11, comprising the step of exposing the optically transparent material to further UV light to complete curing after cleaning.

13. The method of any of claims 9-12, wherein the microsphere lens comprises a single microsphere.

14. The method of any of claims 9-12, wherein the microsphere lens comprises an array of microspheres.

15. The method of claim 14, wherein the array of microspheres is formed by providing a suspension comprising a plurality of microspheres in water and evaporating the water.

16. The method of any one of claims 13 to 15, comprising the additional step of truncating the microsphere lenses.

17. The method of claim 16, wherein truncation is achieved by cutting a microsphere comprising the microsphere lens at a desired distance using a Focused Ion Beam (FIB) system.

18. The method of claim 16, wherein truncation is effected by grinding microspheres comprising said microsphere lenses until a desired truncated shape is achieved.

19. An objective lens or an objective lens arrangement comprising a microsphere lens assembly according to any one of claims 1 to 8.

20. Super-resolution microscopic equipment, characterized by including: a microscope, and an objective lens or an objective lens arrangement as claimed in claim 20.

21. The super-resolution microscopy apparatus according to claim 20, wherein the apparatus comprises an illumination device operable to illuminate the sample in a reflective or transmissive mode.

22. The super resolution microscopy apparatus according to claim 20 or 21, wherein the apparatus is provided with a restricted aperture between the illumination means and the microsphere lens assembly.

23. The super resolution microscopy apparatus according to any one of claims 20-22, wherein the apparatus is provided with an imaging device operable to capture images of the sample viewed through the objective lens.

24. The super-resolution microscopy apparatus according to claim 23, wherein the imaging means is connected to an image processing means, the image processing means being operable to process the captured image.

25. The super resolution microscopy device of any one of claims 20-24, wherein the device comprises a sample holder on which a sample can be positioned such that it can be viewed through the microsphere lens assembly.

26. The super resolution microscopy apparatus of claim 25, wherein the sample holder is operable to controllably vary a spacing between the microsphere lens assembly and the sample, and wherein the sample holder is operable to controllably vary a position of the sample relative to the microsphere lens assembly in a plane perpendicular to an optical axis of the microsphere lens assembly.

27. The super resolution microscopy device of any one of claims 20-26, wherein the device comprises a plurality of objective lenses.

28. The super resolution microscopy apparatus of claim 27, wherein each objective lens comprises a microsphere lens assembly.

29. The super-resolution microscopy device according to any one of claims 20 to 28, wherein the device is provided with a machining laser beam source.

30. The super resolution microscopy apparatus of claim 29, wherein the processing laser beam is directed through the microsphere lens assembly.

31. A super resolution microscopy method using the microscopy apparatus of any one of claims 20-30, the method comprising the steps of: providing a sample; positioning a microsphere lens assembly relative to the sample; and capturing one or more images of the sample.

32. The method of claim 31, comprising varying a spacing between the microsphere lens assembly and the sample.

33. The method of claim 31 or 32, comprising changing the position of the sample relative to the microsphere lens assembly in a plane perpendicular to the optical axis of the microsphere lens assembly.

34. The method of any one of claims 31-33, comprising introducing a liquid between the microsphere lens assembly and the sample.

35. A method as claimed in any one of claims 31 to 34, comprising processing the captured image.

36. The method according to any one of claims 31 to 35, comprising the additional step of processing the sample by: providing a machining laser beam source aligned such that a machining laser beam passes through said microsphere lens assembly; and exposing the target surface of the sample to the processing laser beam to process the target surface.

37. A method of processing using the microscopy apparatus of any one of claims 20-30, the method comprising the steps of: providing a sample; positioning the microsphere lens assembly relative to the sample; providing a machining laser beam source aligned such that a machining laser beam passes through said microsphere lens assembly; and exposing the target surface of the sample to the processing laser beam to process the target surface.

Technical Field

The present invention relates to a microsphere lens assembly. In particular, the present invention relates to a microsphere lens assembly in which the microspheres are attached to the objective lens of a microscope. The invention also relates to the manufacture and use of such microsphere lens assemblies.

Background

Due to the existence of far-field diffraction limit, the resolution of the conventional optical microscopy imaging has a theoretical limit of about 200nm in the visible spectrum; this has led to conventional optical microscopy imaging being unsuitable for imaging objects with structures below this limit, for example live viruses (typically 5-150nm, some up to 300 nm). Other techniques have been used in order to image these structures beyond the optical diffraction limit.

Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) are commonly used to image specially prepared dead virus structures in vacuum at very high resolution (10 nm). These techniques require complex sample preparation procedures and are not suitable for in vivo imaging and detection (e-beam can affect living cells, viruses, etc.).

Atomic Force Microscopy (AFM) can image small structured samples well with a contact probe. The sample is susceptible to damage from the AFM tip. Furthermore, the technique does not provide true images, but rather reconstructed images.

Stimulated emission depletion (STED) fluorescence microscopy is a recently established method capable of imaging cellular structures, bacteria and viruses beyond the optical diffraction limit with as low as 6nm resolution. This technique is based on the detection of light emitted by a fluorescent sample when it is excited by laser light of a particular wavelength and the use of laser light of a different wavelength to turn off part of the fluorescent region. STED fluorescence microscopy may provide better resolution but requires complex preparation of the sample (fluorescent labeling), which is not always suitable for imaging of living organisms. Fluorescence imaging techniques can provide good results mainly for organic samples. However, for high resolution, this technique faces the challenge of photobleaching, which limits the minimum exposure time to tens of seconds.

In recent years, super-resolution imaging has been demonstrated using an array of microspheres positioned between the objective lens and the sample. The microspheres used in such arrays typically have a diameter in the order of 10 μm. The use of microspheres enables the capture of evanescent waves that exist at the boundary of two different media with different refractive indices in the "far field" region. These evanescent waves carry high spatial frequency sub-wavelength information and decay exponentially with distance. Thus, microspheres near the surface are more effective than conventional objectives in detecting the evanescent wave.

CN102305776B discloses microspheres with a diameter of 1-9 μm used as lenses, which are in contact with or at a distance of less than 100nm from the object to be imaged. The object to be imaged must be a metal sample or a gold-plated sample (for semiconductor materials). The detection mechanism is based on detecting surface plasmons that occur between the metal and the non-metal. There are two types of microsphere holders: conical holes in silicon 8 μm on top and 2.8 μm on bottom, using UV-curing adhesive to fix the microspheres; transparent glass tips, using UV-curing adhesive to fix the microspheres. Such structures are not particularly robust or are not suitable for easy assembly onto existing microspheres. Furthermore, the microspheres are not attached to the objective lens and therefore cannot be guaranteed to be alignable with the optical axis of the objective lens.

WO2015/025174a1 discloses an array of microspheres embedded in a host material (elastomeric, glass or plastic) and placed on a workpiece. Such a lens sheet can be reused for imaging. Microsphere arrays are difficult to manufacture and are fragile and easily damaged. The use of such small microspheres also presents difficulties with increased distortion of the image and a more limited field of view. Furthermore, the microspheres are not attached to the objective lens and therefore cannot be guaranteed to be alignable with the optical axis of the objective lens.

The super-resolution imaging device may also be adapted for use in laser-based micromachining. In this technique, the processing resolution is limited by the spot size of the focused laser beam. This size is half the wavelength of the laser and therefore, it is difficult to process sub-wavelength structures. Previous research work demonstrated that super-resolution imaging or sub-wavelength laser processing can be performed using microspheres dispersed on the surface of a target object. For practical processing techniques, the microspheres may not be placed on the processing object. There is therefore a need for a mounting structure that is simple, robust, accurately positionable, and easily assembled to existing microscopes.

It is therefore an object of the present invention to enable super-resolution microscopy and/or micromachining that at least partially overcomes or alleviates some of the above problems.

Disclosure of Invention

According to a first aspect of the present invention there is provided a microsphere lens assembly comprising a base lens, a microsphere lens and a cylinder of optically transparent material extending from a front surface of the base lens to the microsphere lens.

The above assembly may be used as an objective lens for a microscope or as a front lens for an objective lens arrangement. Thus, the assembly enables the microscope to be used for super resolution microscopy and laser micromachining. Fixing the microsphere lens to the base lens through the post enables the microsphere lens to be accurately positioned at a fixed distance from the base lens and aligned with the optical axis when in use for optimal performance. Securing the microsphere lenses in place also provides a simple and secure attachment means. Such systems are suitable for metallic and non-metallic target materials, particularly for imaging and processing biological samples (e.g., cells).

For the purposes of this application, an optically transparent material is transparent or substantially transparent to visible light.

The microsphere lenses may comprise microspheres or truncated microspheres. The use of microspheres rather than truncated microspheres may improve resolution but also increase distortion. For the avoidance of doubt, truncated microspheres include microspheres that are truncated by a plane perpendicular to the optical axis. In some embodiments, the truncated microspheres may comprise hemispheres.

In some embodiments, the microsphere lenses may comprise an array of microspheres. The array of microspheres may be formed by any suitable method, including, but not limited to, self-assembly. In some embodiments, the microsphere lenses may comprise an array of truncated microspheres. Such truncated microspheres may comprise hemispheres.

The microspheres comprising the microsphere lenses may have a diameter of 1-1000 μm. In one embodiment, the microspheres may have a diameter of 90-106 μm. In particular, the microspheres may have a diameter of about 100 μm. In another embodiment, the microspheres may have a diameter of 5-15 μm.

The microsphere comprising the microsphere lens may have a refractive index of 1.5 to 4. In one embodiment, the microspheres may have a refractive index of 1.55-2.4. In particular, the microsphere lenses may have a refractive index of about 1.9-2.2.

The microspheres comprising the microsphere lenses may be formed of any suitable material, including, but not limited to, barium titanate (BaTiO)₃) Polystyrene, silicon dioxide (SiO2), diamond, sapphire (Al)₂O₃) Titanium dioxide, cubic zirconia, zinc oxide, silicon, germanium, gallium phosphide, gallium arsenide, and the like.

The optically transparent material may comprise glass or a suitable plastic. In these embodiments, the optically transparent material may be preformed into the cylinder by a suitable technique including, but not limited to, molding or machining. In these embodiments, the preformed column may be adhered to the base lens and the microsphere lens by a suitable adhesive. Suitable adhesives may include NOA81, MY-132, MY132A, and the like.

The optically transparent material may include an adhesive or a resin. Preferably, the optically transparent material is UV light curable. Where the optically transparent material is an adhesive, it may comprise an adhesive such as NOA81, MY-132, MY132A, or the like.

The geometry of the pillars formed by the optically transparent material is determined by the relative optical properties and dimensions of the microsphere lenses and the base lens. In particular, the geometry of the pillars formed by the optically transparent material is selected such that the microsphere lenses as a whole are capable of focusing light from a sample for imaging or for processing purposes onto the sample. In a preferred embodiment, the posts extend from the edge of the base lens to the edge of the microsphere lens. Since the microsphere lenses are generally narrower than the base lens, the pillars may be tapered pillars. The taper of the cylinder may be constant or variable.

According to a second aspect of the present invention there is provided a method of constructing a microsphere lens assembly, comprising the steps of: attaching a base lens to a microscope; providing a microsphere lens on a sample; applying an optically clear and UV light curable material between the base lens and the microsphere lenses; adjusting the spacing between the microsphere lens and the base lens until the microsphere lens is centered in the field of view of the base lens and the sample is in focus; illuminating the back side of the base lens with UV light; and separating the base lens from the sample.

The method of the second aspect of the invention may include any or all of the features of the first aspect of the invention as required or desired.

The above method provides a simple way of constructing an effective microsphere lens assembly for super resolution microscopy. Centering and focusing may ensure that the microsphere lens is positioned in a desired position relative to the base lens. Illuminating the centered and focused microsphere lenses with UV light can cure the pillars formed of optically transparent material with the microspheres at the tips of the pillars. Separating the base lens from the sample enables the microsphere lenses and columns to be lifted off the sample.

In a preferred embodiment, the sample is a known sample. In particular, the sample may be a dedicated calibration sample.

The method may include the step of cleaning off excess optically transparent material after illuminating the back surface of the base lens with UV light. Cleaning may be accomplished by any suitable method including, but not limited to, wiping off excess material using a suitable cloth or paper towel. Additionally or alternatively, cleaning may involve the use of a suitable solvent. The particular solvent selected may vary depending on the particular optically transparent material selected. Suitable solvents may include, but are not limited to, isopropanol, sodium hydroxide (preferably dilute sodium hydroxide), potassium hydroxide (preferably dilute potassium hydroxide), and the like.

In some cases, illuminating the back surface of the base lens with UV light does not result in complete curing of the optically transparent material. In this case, the method may comprise the step of further exposing the optically transparent material to UV light to complete curing. This further exposure to UV light is preferably performed after cleaning. Further exposure to UV light may be provided by an external light source.

In some embodiments, the microsphere lenses may comprise a single microsphere. In other embodiments, the microsphere lenses may comprise an array of microspheres. The array of microspheres may be formed by any suitable method including, but not limited to, self-assembly. Self-assembly may involve the steps of providing a suspension containing a plurality of microspheres in water and evaporating the water. Next, self-assembly may involve applying an adhesive to the array of microspheres to hold the microspheres in place. In some embodiments, the adhesive may be subsequently cured. Curing may involve exposure to UV light or any other suitable method.

The method may include the additional step of truncating the microsphere lenses. The truncation is preferably performed after the assembly is formed. Truncation may be achieved using any suitable method. In one embodiment, truncation may be achieved by cutting one or more microspheres including a microsphere lens at a desired distance using a Focused Ion Beam (FIB) system. In another embodiment, truncation may be achieved by grinding one or more microspheres comprising the microsphere lenses until the desired truncated shape is achieved. The grinding may be performed using a grinding table equipped with diamond paste. To achieve a polished cut surface, various different diamond pastes may be applied sequentially.

According to a third aspect of the present invention there is provided an objective lens or objective lens arrangement comprising a microsphere lens assembly according to the first aspect of the present invention.

The objective lens or objective lens arrangement of the third aspect of the invention may include any or all of the features of the first and second aspects of the invention as required or desired.

According to a fourth aspect of the present invention, there is provided a super-resolution microscopy apparatus comprising: a microscope, and an objective lens or an objective lens arrangement according to the third aspect of the invention.

The apparatus of the fourth aspect of the present invention may include any or all of the features described in the first to third aspects of the present invention as required or appropriate.

The apparatus may comprise illumination means operable to generate light for illuminating the sample. The light produced may be of a monochromatic or broad spectrum, as desired or required. The illumination device is operable to illuminate the sample in a reflective or transmissive mode. In embodiments where the illumination means is operable to illuminate the sample in a reflective mode, the apparatus is provided with a restricted aperture between the illumination means and the microsphere lens assembly. The restricted aperture is operable to provide a narrow illumination beam, thereby improving resolution.

The apparatus may be provided with an imaging device operable to capture an image of the sample viewed through the objective lens. Typically, the imaging device may comprise an optical sensing array, for example a CCD (charge coupled device) array.

The imaging device may be connected to an image processing device operable to process the captured image. The processing operation may include a process for removing radial (pincushion) distortion towards the edge of the microsphere lens. Additionally or alternatively, the processing may include other steps such as filtering, shadow removal, edge detection, inversion, and the like.

The apparatus may comprise a sample holder on which the sample may be placed such that it may be viewed through the microsphere lens assembly. The sample holder is operable to controllably vary a spacing between the microsphere lens assembly and the sample. The sample holder is operable to controllably vary a position of the sample relative to the microsphere lens assembly in a plane perpendicular to an optical axis of the microsphere lens assembly. In this case, the sample holder may comprise a scanning stage. This enables scanning of the sample relative to the microsphere lens assembly such that an increased area of the sample can be imaged.

The apparatus may comprise a plurality of objective lenses. In this case, the sample may include means for switching between the objectives. In such embodiments, each objective lens may comprise a microsphere lens assembly.

The objective lens may be adapted such that the objective lens is removed or replaced. Alternatively, the objective lens arrangement may be adapted such that the front lens is removed or replaced.

The apparatus may be provided with a machining laser beam source. A machining laser beam may be directed through the microsphere lens assembly. This allows the apparatus to be used for micro-machining of target surfaces. In particular, this enables sub-wavelength laser machining of the target surface.

According to a fifth aspect of the present invention, there is provided a super-resolution microscopy method using the microscope of the fourth aspect of the present invention, the method comprising: providing a sample; positioning a microsphere lens assembly relative to the sample and capturing one or more images of the sample.

The method of the fifth aspect of the invention may include any or all of the features of the previous aspects of the invention as required or desired.

The method may comprise varying the spacing between the microsphere lens assembly and the sample. The method may comprise changing the position of the sample relative to the microsphere lens assembly in a plane perpendicular to the optical axis of the microsphere lens assembly. In particular, the method may involve scanning the sample relative to the microsphere lens assembly. This allows imaging of an increased area of the sample.

The method may comprise introducing a liquid between the microsphere lens assembly and the sample. The liquid may be introduced by application to the sample.

The method may include processing the captured image. In particular, the method may comprise a process for removing radial distortion. Additionally or alternatively, the method may include other steps such as filtering, shadow removal, edge detection, inversion, and the like.

The method may include the additional step of processing the sample. The processing can be achieved by the following steps: providing a source of a machining laser beam aligned such that it passes through the microsphere lens assembly; and machining the target surface of the sample by exposing the target surface to the machining laser beam. Processing may be performed simultaneously with imaging.

According to a sixth aspect of the present invention, there is provided a machining method using the microscope of the fourth aspect of the present invention, the method comprising: providing a sample; positioning the microsphere lens assembly relative to the sample; providing a machining laser beam source aligned such that a machining laser beam passes through said microsphere lens assembly; and processing the target surface of the sample by exposing the target surface to the processing laser beam.

The method of the sixth aspect of the invention may include any or all of the features of the previous aspects of the invention as required or desired.

Drawings

In order that the technical solution of the invention may be more readily understood, embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a microsphere lens assembly for a microscope comprising a single microsphere in one embodiment of the invention;

FIG. 2 schematically illustrates assembly of the microsphere lens assembly of FIG. 1 onto an objective lens arrangement;

FIG. 3 schematically illustrates a series of steps for manufacturing the microsphere lens assembly shown in FIG. 1;

FIG. 4 illustrates a microsphere lens assembly for a microscope comprising a single truncated microsphere in an alternative embodiment of the invention;

FIG. 5 illustrates a truncated microsphere for use in the microsphere assembly shown in FIG. 4;

FIG. 6 illustrates a microsphere lens assembly for a microscope including an array of microspheres in an embodiment of the invention; and

FIG. 7 illustrates a microsphere lens assembly for a microscope comprising an array of truncated microspheres, in an embodiment of the invention.

Detailed Description

Referring to FIG. 1, a microsphere lens assembly 10 is shown for use with a microscope. The microsphere lens assembly 10 comprises a microsphere lens 1 and a base lens 3 which are connected together by a cylinder of optically transparent material 2. In the example shown in fig. 1, the microsphere lens 1 is in the form of a single microsphere 11.

The cylinder of optically transparent material 2 holds the microsphere lenses 1 in a fixed position relative to the base lens 3. If the microsphere lens 1 is fixed in the correct position with respect to the base lens 3, the assembly 10 may be used in conjunction with a suitable microscope for performing super-resolution microscopy and/or machining.

For practical embodiments, the base lens 3 may comprise the objective lens of a microscope, or the front lens of an objective lens arrangement. In a preferred embodiment, as shown in fig. 2, the base lens 3 is a removable front lens of the objective lens arrangement 6. Such a lens arrangement 6 may typically comprise a series of selected lenses fitted at a fixed distance from each other within a housing 7. The front lens support 5 is releasably attachable to the housing 7, which releasable attachment may be by means of threads or the like. This allows the front lens to be removed for cleaning and/or replaced if it is damaged. This is cheaper and simpler than repairing or replacing the entire objective lens arrangement 6.

In this example, the front lens holder 5 is adapted to engage with the rim 4 of the base lens 3 to releasably retain the base lens 3 and the lens assembly 10 within the holder. Thus, when the lens assembly 10 is damaged, it can be removed for repair or replacement.

Reference is now made to fig. 3(a) -3(f), which schematically illustrate a method of manufacturing the lens assembly of fig. 1. A microsphere lens 10 comprising in this example a single microsphere 11 is placed on a known sample 30. The sample is placed on a scanning stage 21 of a microscope 20. The objective lens 22 to which the microsphere lens assembly 10 is to be mounted is selected. The objective lens 22 comprises an objective lens arrangement 6 as shown in fig. 2 located within a housing 7 and has a removable front lens 3, which front lens 3 will form the base lens 3 of the microsphere assembly. At this stage the objective lens 22 and scanning stage may be adjusted to center the microsphere lens 10 in the field of view of the objective lens 22 and to focus the objective lens 22 so that the specimen 20 viewed through the objective lens 22 and microsphere lens 10 is partially in focus.

As shown in fig. 3(b), an optically transparent UV-curable adhesive (or resin) 40 is applied between the front lens 3 and the microsphere lens 1. This results in the formation of an adhesive body 41 between the front lens 3 and the microsphere lens 1, as shown in fig. 3 (c). The adhesive 40 must be selected to have suitable properties for imaging (or processing) of the sample to be used with the finished assembly. For example, if the assembly 10 is to be used for fluorescence imaging, the adhesive 40 must have very good UV light transparency. Similarly, if the assembly 10 is to be used for imaging or processing using microsphere lenses 1 having a relatively high refractive index (e.g., 1.5 or higher), the adhesive 40 must have very good IR light transparency.

At this stage, final adjustments may be made to the objective lens 22 and the scanning stage 21 to center the microsphere lens 10 in the field of view of the objective lens 22 and to focus the objective lens 22 so that the specimen 30 viewed through the objective lens 22 and the microsphere lens 10 is partially in focus. After the above final adjustment step is completed, the back of the base lens 3 may be illuminated using the UV light source 50. In the example shown in fig. 3(d), the UV light source is positioned at the eyepiece 23 of the microscope 20. In a more typical embodiment, a UV light source may be coupled to a camera port (not shown) or other port for illuminating the sample.

UV light from the light source 50 is focused on the microsphere lenses 1 by the base lens 3 and the objective lens arrangement 6. The UV light cures the cylinder 2 within the body 41 as shown in fig. 3 (e). The duration and intensity of UV light exposure will depend on the nature of the UV adhesive selected to form body 41. The geometry of the cylinder 2 is determined by the optical properties of the base lens 3. Typically, the cylinder 2 has a generally conical shape that tapers between the edge of the base lens 3 and the edge of the microsphere lens 1.

After the cylinder 2 is formed, the uncured material forming the remainder of the body 41 may be removed, leaving the microsphere assembly 10. Typically, removal of excess optically transparent material can be accomplished by washing with a solvent. The pillars 2 may then be illuminated with a second UV light source 55 for an extended period of time for further curing, as shown in fig. 3 (f). The cylinder 2 and/or microsphere lenses 1 may then optionally be further cleaned and polished as needed or desired.

Thus, the above method provides a simple and effective method of construction of a microsphere lens assembly 10 for super resolution microscopy or machining. Because this method is relatively simple, it may be used to form a plurality of microsphere lens assemblies 10 using spare base lenses 3. This allows for easy replacement of a component 10 that is damaged during use. Additionally or alternatively, a plurality of microsphere lens assemblies 10 may be formed from different combinations of base lenses 3 and microsphere lenses 1. This allows for the formation of different microsphere lens assemblies 10 with optimized performance for different sample imaging or processing.

For example, as shown in fig. 4, the microsphere lens 1 of the microsphere lens assembly 10 comprises truncated microspheres 12. Such an assembly 10 may be formed using microspheres 11 by the same steps as in fig. 3(a) -3(f) and an additional step of removing the spherical cap portion from the front of the microsphere 11 leaving a truncated front surface 13.

This removal may be performed by any suitable method. In one example, this removal operation may be accomplished by cutting the microspheres 11 using a focused ion beam. In an alternative example, this removal may be accomplished by grinding the microspheres 11 using a grinding table. The grinding table may utilize different diamond slurries one after the other to enable rapid removal of material at the beginning of the process and polishing of the front surface 13 at the end of the process.

An assembly 10 having a shorter sample to microsphere lens 1 separation distance than the assembly 10 shown in fig. 1, as shown in fig. 4, may be effectively utilized. The reduction in separation distance is related to the amount of material cut away to form truncated microspheres 12. FIG. 5 shows how truncated microspheres 12 are defined by two variables (a and h); the distances h and a can reach a maximum length equal to the radius r of the microspheres. In the case where a ═ r, the truncated microspheres 12 are hemi-microspheres.

The larger the value of h, the smaller the numerical aperture for a given microsphere diameter, refractive index and wavelength. The effective field of view (a) of truncated microspheres 12 without aberrations is given by: a ═ pi a²。

In addition to an assembly 10 comprising a single microsphere 11 or truncated microspheres 12, an assembly 10 comprising an array of microspheres 11 of the microsphere lens 1 may also be provided, as shown in fig. 6. Such an assembly may be formed using the same method as described above for FIGS. 3(a) -3(f), except that the initial step is to place microsphere array 14 on sample 30. The array of microspheres 11 may be formed by any suitable method. In this example, for a relatively small array, the array may be formed by self-assembly after placement of a droplet (typically a water droplet) of microspheres 11 suspended at a suitable concentration. As the water evaporates, the microspheres 11 self-assemble into a dense array.

In another embodiment shown in fig. 7, the microsphere lens 1 comprises an array of truncated microspheres 12. Such an assembly 10 may be formed using the same method as described above in connection with fig. 3(a) -3(f) and the initial step of providing an array of microspheres 11 on a sample 30 as mentioned above in connection with fig. 6. The method of manufacturing the assembly 10 shown in fig. 7 also includes the additional step of removing the spherical cap portion from the front of each microsphere 11 leaving a truncated front surface 13. This removal may be accomplished by using a focused ion beam or a polishing table as described above with respect to fig. 4.

The microsphere lens assembly 10 described above may be used to image the sample 30 and/or process the sample 30 as desired or needed.

Although the above embodiments have been described primarily based on forming the microsphere lens assembly 10 on a base lens 3 comprising a front lens of an objective lens arrangement, it will be understood by those skilled in the art that such an assembly 10 may also be formed on a base lens comprising a single objective lens.

The above embodiments have been described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.