RE-SCAN MICROSCOPE SYSTEM AND METHOD

Abstract

A re-scan microscope for forming an image of a sample is disclosed. The system comprises an illumination optical system for directing, and optionally focusing, illumination light at the sample herewith providing an illumination light spot at the sample. The illumination light spot causes emission light from the sample. The microscope system further comprises a detection optical system for focusing at least part of the emission light onto an imaging plane of an imaging system herewith causing an emission light spot on the imaging plane. The microscope system also comprises a rotatable element for, when rotating, moving the illumination light spot over and/or through the sample and simultaneously moving the emission light spot over said imaging plane of the imaging system. The rotatable element comprises at least two reflective surfaces.

Claims

1. A re-scan microscope system for forming an image of a sample, comprising: an illumination optical system configured to direct, and optionally focus, illumination light at the sample therewith providing an illumination light spot at the sample, the illumination light spot causing emission light from the sample; a detection optical system configured to focus at least part of the emission light onto an imaging plane of an imaging system herewith causing an emission light spot on the imaging plane; and a rotatable element for, when rotating, moving the illumination light spot over and/or through the sample and simultaneously moving the emission light spot over said imaging plane of the imaging system, wherein the rotatable element comprises at least two non-parallel reflective surfaces.

2. The re-scan microscope system according to claim 1, wherein the rotatable element is configured to rotate over an angle of at least 90 degrees about an axis of rotation.

3. The re-scan microscope system according to claim 1, wherein the rotatable element comprises a first reflective surface and a second reflective surface, and wherein the re-scan microscope system is configured such that, in use, during a rotation of the rotatable element, the first reflective surface reflects the illumination light throughout a first time period and changes orientation during said first time period for moving the illumination light spot over and/or through the sample.

4. The re-scan microscope system according to claim 3, wherein the re-scan microscope system is configured such that, in use, during said first time period, the second reflective surface reflects the emission light and changes orientation during said first time period for moving the emission light spot over the imaging plane.

5. The re-scan microscope system according to claim 4, wherein the re-scan microscope system is configured such that, in use, during the rotation of the rotatable element, the second reflective surface reflects the illumination light throughout a second time period and changes orientation during said second time period for moving the illumination light spot over and/or through the sample and configured such that, during said second time period, a further reflective surface of the rotatable element reflects the emission light and changes orientation during said second time period for moving the emission light spot over the imaging plane.

6. The re-scan microscope system according to claim 3, wherein the re-scan microscope system is configured such that, in use, during said first time period, the first reflective surface reflects the emission light and changes orientation during said first time period for moving the emission light spot over the imaging plane and such that, in use, during the rotation of the rotatable element, the second reflective surface reflects the illumination light throughout a second time period and changes orientation during said second time period for moving the illumination light spot over and/or through the sample.

7. The re-scan microscope system according to claim 6, wherein the re-scan microscope system is configured such that, in use, during said second time period, the second reflective surface reflects emission light and changes orientation during said second time period for moving the emission light spot over the image plane.

8. The re-scan microscope system according to claim 1, wherein the rotatable element comprises a rotatable polygon scanner comprising a plurality of reflective facets, wherein the first reflective surface is a first facet of the plurality of reflective facets and the second reflective surface is a second facet of the plurality of reflective facets.

9. The re-scan microscope system according to claim 1, wherein the re-scan microscope system is configured to move the illumination light spot over and/or through the sample at a first velocity and move the emission light spot over the imaging plane at a second velocity, such that the second velocity is different from a baseline velocity, wherein the baseline velocity is defined as the first velocity multiplied by the optical magnification of the re-scan microscope system.

10. The re-scan microscope system according to claim 16, wherein the second velocity is approximately twice as high as the baseline velocity.

11. The re-scan microscope system according to claim 9, comprising an objective configured to gather the emission light from the sample and focus the emission light on a primary image plane of the re-scan microscope system, wherein the detection optical system is configured to image images in the primary image plane onto the imaging plane of the imaging system, preferably with an optical magnification of approximately 0.5.

12. The re-scan microscope system according to claim 1 that is configured such that, in use, an angle between a travel direction of the illumination light that is incident on the rotatable element and a travel direction of the emission light that is incident on the rotatable element for moving the emission light spot over the imaging plane is less than 90 degrees.

13. The re-scan microscope system according to claim 1, wherein the rotatable element is configured to reflect the illumination light in a first variable direction and to reflect the emission light for moving the emission light spot over the imaging plane in a second variable direction, wherein the angle between the first and second variable direction is larger than 90 degrees.

14. The re-scan microscope system according to claim 1, wherein the system comprises an aperture configured to pass emission light and an optical system for focusing the emission light onto the aperture.

15. A method for forming an image of a sample using a re-scan microscope system, the re-scan microscope system comprising an illumination optical system for directing, and optionally focusing, illumination light at the sample therewith providing an illumination light spot at the sample, the illumination light spot causing emission light from the sample, and the re-scan microscope system comprising a detection optical system focusing at least part of the emission light onto an imaging plane of an imaging system herewith causing an emission light spot on the imaging plane, and a rotatable element comprising at least two non-parallel reflective surfaces, and in that the method comprises rotating the rotatable element for moving the illumination light spot over and/or through the sample and simultaneously moving the emission light spot over said imaging plane of the imaging system.

16. The re-scan microscope system according to claim 9, wherein the second velocity is higher than the baseline velocity.

17. The re-scan microscope system according to claim 11 wherein the detection optical system is configured to image images in the primary image plane onto the imaging plane of the imaging system with an optical magnification of approximately 0.5.

18. The re-scan microscope system according to claim 12 wherein the imaging plane is less than 60 degrees.

19. The re-scan microscope system according to claim 18 wherein the imaging plane is less than 30 degrees.

20. The re-scan microscope system according to claim 13 wherein the angle between the first and the second variable direction is larger than 120 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Aspects of the invention will be explained in greater detail by reference to exemplary embodiments shown in the drawings, in which:

[0068] FIG. 1 schematically shows a re-scan microscope system according to an embodiment;

[0069] FIG. 2 schematically shows, in three dimensions, a re-scan microscope system according to an embodiment;

[0070] FIGS. 3A-3C illustrate scanning and re-scanning as performed by the rotatable element during a rotation according to an embodiment, wherein the scanning and re-scanning functions are performed by different reflective surfaces;

[0071] FIGS. 4A-4C illustrate scanning and re-scanning as performed by the rotatable element during a rotation according to an embodiment, wherein the scanning and re-scanning functions are performed by a single reflective surface;

[0072] FIGS. 5A-5C illustrate scanning and re-scanning as performed by the rotatable element during a rotation according to an embodiment, wherein the scanning and re-scanning functions are performed by two parallel reflective surfaces;

[0073] FIGS. 6A-6B illustrate the movement of illumination light in a primary image plane and corresponding movement of the emission light spot in the imaging plane of the imaging system according to an embodiment;

[0074] FIGS. 7A-7B show rotatable elements according to two different embodiments;

[0075] FIG. 8 shows a data processing system according to an embodiment that may be used in a re-scan microscope system according to an embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0076] In the figures, identical reference numerals indicate identical or similar elements.

[0077] FIG. 1 schematically shows a re-scan microscope system 10 for forming an image of a sample 32 according to one embodiment. A light source, such as a laser 11, generates illumination light 16. An optical fiber cable 12 may be used to guide the illumination light 16 from light source 11 to the re-scan microscope system 10. A collimating lens 14 converts the divergent illumination light as output by the optical fiber cable 12 into a parallel beam.

[0078] The system 10 comprises an illumination optical system for directing the illumination light 16 at the sample. In the depicted embodiment, the illumination optical system comprises a dichroic mirror 18, a y-axis scan system 20a, relay optics comprising lenses 22a and 22b, a first reflective surface 24a, such as a mirror, of a rotatable element 25, a scan lens 26, a tube lens 28 and an objective 30. The illumination optical system is configured to direct, and optionally focus, the illumination light 16 at the sample. Herewith, an illumination light spot 34 is provided at the sample 32. In this example, the illumination light spot is positioned in plane 36 through the sample 32. The sample may be fluorescently labelled and may be a biological sample.

[0079] The illumination light spot 34 at the sample 32 causes emission light 46 from the sample. In one example, the illumination light spot causes optical excitations in the sample 32, which optical excitations, upon decaying to lower energy levels, cause the emission light. In this example, the illumination light 16 may be regarded as excitation light and the emission light as fluorescent light. In another example, the illumination light spot causes emission light from the sample 32 in the sense that the illumination light is reflected by the sample 34. The reflected light may also be regarded as emission light 46, in particular as reflection emission light.

[0080] The re-scan microscope system 10 further comprises a detection optical system for focusing the emission light onto an imaging plane 56 of an imaging system 52. Herewith an emission light spot 54 is caused on the imaging plane 56. The imaging system may be a camera, such as a CCD camera. The imaging plane preferably comprises a plurality of pixels that are arranged in a predefined manner. e.g. in a 2D lattice. In the depicted embodiment, the detection optical system comprises scan lens 26, reflective surface 24a, relay lenses 22a and 22b, y-axis scan system 20a, mirror 38, a pinhole 42, lenses 40a and 40b positioned on either side of pinhole 42, mirror 44, y-axis scan unit 20b, relay lenses 22c and 22d, a second reflective surface 24g and re-scan lens 50. However, it should be appreciated that the depicted detection optical system is merely an example and that the detection optical system used for the invention may in principle comprise less, or more, optical elements, such as mirrors and lenses, than depicted in FIG. 1.

[0081] The depicted embodiment comprises a dichroic mirror 18 that is configured to reflect illumination light 16 travelling towards the sample 32 and to pass emission light 46 travelling from sample 32 to the imaging system 52.

[0082] The rotatable element 25 is configured to rotate over an angle of at least 360 degrees and herewith move the illumination light spot 34, provided by the illumination optical system, over and/or through the sample 32. In the depicted embodiment, the illumination light spot 34 moves over plane 36 that lies through sample 32. The rotatable element 25 also performs another function. Due to its rotation, the rotatable element 25 namely simultaneously moves the emission light spot 54, caused by the detection optical system, over the imaging plane 56. In one embodiment, the rotatable element 25 is configured to consecutively make a plurality of full rotations. Preferably, the rotatable element can rotate infinitely.

[0083] For each rotation of the rotatable element, each reflective surface of the rotatable element may perform a scanning function and/or a re-scanning function at least once, preferably once.

[0084] It should be understood that the reflective surface 24a may both scan the illumination light so that the illumination light spot moves over and/or through the sample 32 as well as de-scan the emission light 46 from the sample 32 so that a static light beam of emission light is formed between reflective surface 24a and reflective surface 24g. Static may be understood as not moving with respect to the rotational axis 60 of the rotatable element 25.

[0085] Each reflective surface 24a-24h of the rotatable element 25 has a normal vector. Preferably, the respective normal vectors of the reflective surfaces lie in the same plane. Preferably, this plane is perpendicular to the axis of rotation of the rotatable element. In one embodiment, the normal vectors of the reflective surfaces make equal angles with respect to each other.

[0086] In an embodiment, adjacent reflective surfaces of the rotatable element are oriented at an angle with respect to each other that is smaller than 90 degrees, i.e. the respective normal vectors of the adjacent surfaces make an angle with respect to each other that is smaller than 90 degrees. Note that in the depicted example, the normal vectors are directed away from the rotational axis of the rotatable element.

[0087] The reflective surfaces may be fixed onto the rotatable element. In an embodiment, the orientation of each of the reflective surfaces with respect to the rotatable element may be adaptable in order to ease alignment of the optical system.

[0088] In an embodiment, the rotatable element 25 comprises a rotatable polygon scanner comprising a plurality of reflective facets 24a. 24g, wherein the first reflective surface 24a is a first facet 24a of the plurality of reflective facets and the second reflective surface 24g is a second facet 24g of the plurality of reflective facets. In principle, the polygon scanner may comprise any number of facets. In the depicted embodiment, other facets are indicated by 24b. 24c. 24d, 24e, 24f. 24h.

[0089] The depicted re-scan microscope system 10 is configured such that, in use, during a rotation of the rotatable element 25, the first reflective surface 24a reflects the illumination light 16 throughout a first time period and changes orientation during said first time period for moving the illumination light spot 34 over and/or through the sample 32. In one embodiment, the re-scan microscope system 10 is configured such that, in use, during said first time period, the second reflective surface 24g reflects the emission light 46 and changes orientation during said first time period for moving the emission light spot 54 over the imaging plane 56.

[0090] In the depicted embodiment, the re-scan microscope system 10 is configured such that, in use, during the rotation of the rotatable element 25, the second reflective surface 24g reflects the illumination light 16 throughout a second time period and changes orientation during said second time period for moving the illumination light spot 34 over and/or through the sample 32 and configured such that, during said second time period, a further reflective surface 24e of the rotatable element 25 reflects the emission light 46 and changes orientation during said second time period for moving the emission light spot 54 over the imaging plane 56.

[0091] Preferably, the point where the illumination light 16 reflects from the first reflective surface lies in a focal plane of scan lens 26 so that the illumination light spot 34 neatly moves over plane 36. Also, preferably, the point where the emission light reflects from the second reflective surface lies in a focal plane of re-scan lens 50 so that the focused emission light spot 54 neatly moves over imaging plane 56. The same holds, respectively, for the reflective points of the illumination and emission light on the y-axis scanning mirrors 20a and 20b. If required, these points may be “optically” positioned in the focal plane of the scan lens 26 and re-scan lens 50, respectively, using relay optics known in the art. In the depicted embodiment, relay lenses 22a and 22b are configured to optically position the illumination light's reflective point on the y-axis scanner 20a in the focal plane of scan lens 26 and relay lenses 22c and 22d to optically position the illumination light's reflective point on the y-axis scanner 20b in the focal plane of re-scan lens 50. To summarize, both the reflective point on the first reflective surface 24a and the reflective point on the y-axis scanning system 20a are preferably in a conjugate plane of the back focal plane of the scan lens 26. Also, both the reflective point on the second reflective surface 24g and the reflective point on the y-axis scanning system are preferably in a conjugate plane of the back focal plane of the re-scan lens 50.

[0092] In the depicted embodiment, the re-scan microscope system 10 is configured to move the illumination light spot 34 over and/or through the sample 32 at a first velocity, v.sub.1, and move the emission light spot 54 over the imaging plane at a second velocity, v.sub.2, such that the second velocity is different from, preferably higher than, a baseline velocity. The baseline velocity is defined as the first velocity multiplied by the optical magnification of the re-scan microscope system.

[0093] In the depicted embodiment, the microscope system 10 comprises an objective 30 configured to gather the emission light 46 from the sample 32 and focus the emission light 46 on a primary image plane 27 of the re-scan microscope system 10. In the depicted embodiment, the detection optical system is configured to image images in the primary image plane 27 onto the imaging plane 56 of the imaging system 52.

[0094] The optical magnification of the re-scan microscope system 10 is independent of the respective velocities with which the illumination light spot 34 and the emission light spot 54 move over the sample resp, the imaging plane 56. The optical magnification of the re-scan microscope system may be understood to be determined by the optical magnification provided by the combination of objective 30 and tube lens 28, referred to as M.sub.micr in De Luca, and the optical magnification M.sub.2 of the detection optical system. The optical magnification of the detection optical system is determined by scan lens 26, relay lenses 22a-22c, lenses 40a and 40b and re-scan lens 50. Assuming that the relay lenses 22a-22d have equal focal lengths, the optical magnification M.sub.2 of the detection optical system is given by

M.sub.2=(f.sub.40a×f.sub.50)/(f.sub.26×f.sub.40b), wherein f.sub.40a denotes the focal length of lens 40a, etc.

[0095] It should be appreciated that the velocity of the illumination light spot's image in primary image plane 27, v.sub.1P, is given by the multiplication of the first velocity, i.e. the actual velocity of the illumination light spot 34 over and/or through the sample, with the optical magnification of the combination of objective 30 and tube lens 28, i.e. v.sub.1P=v.sub.1×M.sub.micr.

[0096] The baseline velocity, v.sub.B, in the depicted embodiment, assuming equal focal lengths of the relay lenses 22a-22d, is then given by v.sub.B=v.sub.1×M.sub.micr×M.sub.2.

[0097] In one embodiment, the second velocity is approximately twice as high as the baseline velocity, v.sub.2≈2×v.sub.B. This can for example be achieved by configuring the detection optical system such that it images an image in the primary image plane 27 onto the imaging plane 56 of the imaging system 52 with an optical magnification of approximately 0.5, M.sub.2≈2 0.5. In this manner, the second velocity is twice as high as the baseline velocity if v.sub.1P and v.sub.2 are equal.

[0098] In the depicted embodiment, the system 10 comprises an aperture 42, such as a pinhole or slit, for passing emission light 46 and an optical system, in this example comprising lens 40a, for focusing the emission light 46 onto the aperture 42.

[0099] Further, the depicted embodiment comprises a data processing system 100 that comprises means for controlling the rotatable element and/or for controlling the y-axis scanning system 20a and/or 20b and/or for controlling the light source 11 and/or for controlling the imaging system 52.

[0100] FIG. 2 shows an embodiment of the re-scan microscope system 10 in three dimensions. For clarity, the sample and optional further lenses after primary image plane 27 are not shown. The illumination light 16 is incident on dichroic mirror 18, which reflects the illumination light 16 towards y-axis scanning system 20a, in the depicted embodiment towards mirror 20a that is configured to rotate around axis 62. The illumination light 16 is subsequently incident on the rotatable element 25, in the depicted embodiment on polygon scanner 25, that is configured to infinitely rotate around rotational axis 60. Scan lens 26 subsequently focuses the illumination light onto the primary image plane 27. The further lens system that further focuses the illumination light on the sample is not shown. However, it should be appreciated that any movement of the illumination light over primary image plane 27 corresponds to a similar movement of the illumination light spot 34 over and/or through the sample 32. To illustrate, if the illumination light in plane 27 moves in the x-direction, then the illumination light spot 34 will move over and/or through the sample in the x-direction as well, yet with a lower velocity determined by the magnification of said further lens system.

[0101] The emission light 46 from the sample travels back from the sample to the rotatable element 25, which de-scans the emission light 46 so that a static emission light beam is formed that travels back to mirror 20a. Mirror 20a then reflects the emission light 46 to the dichroic mirror 18 that passes the emission light 46 so that the emission light is incident on static mirror 38 and static mirror 44 that are arranged to guide the emission light 46 to scanning mirror 20b. Scanning mirror 20b is also configured to rotate around axis 62. Preferably, the scanning mirrors 20a and 20b are configured to move synchronously. In one embodiment, a single y-axis scanning mirror may be used instead of the two scanning mirrors 20a and 20b.

[0102] After being reflected by mirror 20b, the emission light 46 is incident on a reflective surface of the rotatable element so that the emission light is re-scanned. Herewith, the emission light spot 54 is moved over imaging plane 56 of imaging system 52.

[0103] A rotation of the y-axis scanning mirror 20a causes the illumination light in plane 27 to move the in the y-direction as indicated and thus causes the illumination light spot 34 to move in the y-direction as well over and/or through the sample 32.

[0104] A rotation of the y-axis scanning mirror 20b causes the emission light spot 54 to move in the y-direction as indicated over the imaging plane 56.

[0105] The rotatable element 25 may thus be configured to move the illumination light spot 34 in a particular direction. The first velocity of the illumination light spot 34 as used herein may be understood to be the velocity component in this particular direction. Similarly, the rotatable element 25 may be configured to move the emission light spot 54 in a particular direction. The second velocity of the emission light spot 54 may be understood to be the velocity component in this particular direction.

[0106] In the depicted embodiment, the angle between the travel direction of the illumination light that is incident on the rotatable element and the travel direction of the emission light that is incident on the rotatable element for moving the emission light spot over the imaging plane is the same, i.e. the emission light 46 travels in the −x direction towards the rotatable element and the illumination light 16 also travels in the −x direction towards the rotatable element. Preferably, such angle is less than 90 degrees, preferably less than 60 degrees, more preferably less than 30 degrees.

[0107] In the depicted embodiment, the rotational axis is aligned with the y-axis as indicated on the bottom right. A radial surface may be understood to be a surface that is perpendicular to the rotational axis 60. In the depicted embodiment, any radial surface is thus parallel to the x-z plane as indicated on the bottom right.

[0108] Depending on the orientation of the y-axis scanners 20a and 20b and of the reflective surfaces of the rotatable element, the respective directions of the re-scanned emission light 46 and of the scanned illumination light 16 varies. In particular, the angle between a radial surface of the rotatable element and the direction of the re-scanned emission light depends on the orientation of the y-axis scanning mirror 20b, wherein the angle between a radial surface of the rotatable element and the direction of the scanned illumination light 16 depends on the orientation of the y-axis scanning mirror 20a. Preferably, these angles, during the scanning of the sample are at most 10 degrees.

[0109] FIGS. 3, 4 and 5 show top views of the rotatable element at different time instances during a rotation. FIGS. 3A, 3B, 3C depict three respective time instances during the first time period throughout which the reflective surface 24a scans the illumination light 16.

[0110] FIG. 3 shows an embodiment wherein the re-scan microscope system 10 is configured such that, in use, during said first time period, the second reflective surface 24g reflects the emission light 46 and changes orientation during said first time period for moving the emission light spot 54 over the imaging plane 56.

[0111] For clarity, the de-scanning of the emission light 46 is not shown. Typically, the emission light 46, before passing a dichroic mirror 18, and the illumination light 16 travel along the same path, yet in opposite directions.

[0112] In the depicted embodiment, the illumination light 16 and emission light 46 travel in the same direction before being incident on the rotatable element 25, at least as viewed from the top as depicted.

[0113] Further, in the depicted embodiment, the rotatable element is configured to reflect the illumination light 16 in a first variable direction and to reflect the emission light 46 for moving the emission light spot over the imaging plane in a second variable direction. In the depicted embodiment, the scanned illumination light 16 and the re-scanned emission light 46 travel in substantially opposite directions, i.e. the angle between the travel directions is approximately 180 degrees. Preferably, this angle is larger than 90 degrees, preferably larger than 120 degrees, more preferably larger than 150 degrees so that the imaging system 52 and sample 32 can be positioned on either side of the rotatable element. This for example allows the re-scan microscope system to comprise only two fixed mirrors 38, 44, because no mirrors are required for guiding the scanned illumination light or re-scanned emission light to the sample resp, the imaging system.

[0114] FIGS. 3A, 3B and 3C illustrate that due to the rotation of the rotatable element 25, the orientations of the first and second reflective surfaces change causing the respective reflected light beams 16 and 46 to move as well.

[0115] Because the reflective surfaces 24 of the rotatable element 25 do not rotate around an axis that goes through the reflective surfaces themselves, but around a common axis 60, the respective positions of the reflective point of the illumination light 16 that is scanned and the reflection point of the emission light 46 that is re-scanned may slightly vary. However, the applicant has found that these variations do not deteriorate the formed images outside of acceptable limits. Optionally, these variations may be compensated for by means of appropriate post processing software.

[0116] FIGS. 4A, 4B, 4C depicts three respective time instances during a first time period throughout which the reflective surface 24a scans the illumination light 16 and re-scans the emission light 46.

[0117] FIG. 4 shows an embodiment wherein the re-scan microscope system is configured such that, in use, during the first time period, the first reflective surface 24a reflects the emission light and changes orientation during said first time period for moving the emission light spot 54 over the imaging plane 56 and is configured such that, in use, during the rotation of the rotatable element 25. In this embodiment, a second reflective surface 24g reflects the illumination light 16 throughout a second time period and changes orientation during said second time period for moving the illumination light spot 34 over and/or through the sample 32. In the depicted embodiment, the re-scan microscope system is configured such that, in use, during said second time period, the second reflective surface 24g reflects emission light 46 and changes orientation during said second time period for moving the emission light spot 54 over the image plane 56. Here, the second time period occurs after the first time period, when the reflective surface 24g is positioned to receive the illumination light 16 and the emission light 46.

[0118] At respectively the first, second, third time instance (respectively shown in FIG. 4A. 4B, 4C), the first reflective surface 24a is oriented such that the scanned illumination light 16 respectively follows path (i), path (ii), path (iii) towards the sample 32 and such that re-scanned emission light 46 respectively follows path (iv), path (v), path (vi).

[0119] FIGS. 5A, 5B, 5C show three respective time instances during a first time period wherein a first reflective surface 24a reflects illumination light 16 and a second reflective surface 24g reflects emission light 46. In the depicted embodiment, reflective surfaces 24a and 24g are parallel, in particular oriented at 180 degrees with respect to each other. In this embodiment, the rotatable element comprises a third reflective surface 24h that is not parallel with surface 24a nor with surface 24g. Reflective surface 24h will, upon further rotation of the rotatable element, reflect the illumination light 16 for scanning, during a third time period. During the third time period, another surface, in this example reflective surface 24c, will reflect the emission light 46 for re-scanning.

[0120] FIGS. 6A and 6B respectively show the movement of illumination light 16 in the primary image plane 27 and of the emission light spot 68 in the imaging plane 56.

[0121] When the illumination light 16 passes through plane 27 it is focused and has a point spread function having a width indicated by W. The emission light spot 68 is focused onto imaging plane 56 and the resulting emission light spot 68 has, in the depicted embodiment, a width W/2. As explained above, this difference in size may be due to the lenses in the detection optical system.

[0122] FIG. 6A shows that the illumination light 16 is scanned over the primary image plane 27 with a velocity in the x direction of v.sub.1P. As a result, the illumination light spot 34 moves with a velocity over and/or through the sample in the x direction as well, yet with a lower velocity in the x direction due to the magnification caused by further lenses between the primary image plane 27 and the sample 32. In particular. FIG. 6A illustrates that the illumination light is scanned over the plane 27 so that the illumination light moves along several scan lines 64 over plane 27. As a result, the illumination light spot is also scanned line by line over and/or through the sample 32. Typically, the illumination light scans over each scan line 64 in the same direction, in this example from left to right. After the illumination light has scanned a line. e.g. line 64a, it is moved. e.g. by an incremental rotation of a y-axis scanner 20a, in the −y direction, so that the next line 64b can be scanned. Preferably, y-axis scanner moves incrementally in order to change the y-position of the illumination light and remains steady when the illumination light is scanned by the rotatable element in the x direction.

[0123] FIG. 6B shows that the emission light spot 68 is re-scanned over the imaging plane 56. Similarly, the emission light spot 68 is moved in the x direction by the rotatable element 25 over re-scan lines 66. Preferably, the illumination light 16 in primary image plane 27 and the emission light spot 68 on the imaging plane 56 move synchronously in the sense that the emission light spot 68 starts on a re-scan line 66 (on the left hand side) at the moment the illumination light 16 starts on a corresponding scan line 64 and that the illumination light 16 and emission light spot 68 reach the end of their respective lines at the same time.

[0124] FIG. 7A shows a polygon scanner having 12 facets. In one embodiment, some of the facets may be reflective while other facets are non-reflective.

[0125] It should be appreciated that by increasing the number of facets, the number of scan lines that are written on the sample and imaging plane per rotation of the rotatable element increases. Herewith, the scan speed may be increased.

[0126] FIG. 7B shows yet another embodiment of the rotatable element 25, wherein two mirrors 24a, 24g are attached to the respective ends of two rods 70a, 70g. Again, the rotatable element is configured to rotate around rotational axis 60.

[0127] FIG. 8 depicts a block diagram illustrating an exemplary data processing system that may be used in a computing system as described with reference to FIG. 2.

[0128] As shown in FIG. 8, the data processing system 100 may include at least one processor 102 coupled to memory elements 104 through a system bus 106. As such, the data processing system may store program code within memory elements 104. Further, the processor 102 may execute the program code accessed from the memory elements 104 via a system bus 106. In one aspect, the data processing system may be implemented as a computer that is suitable for storing and/or executing program code. It should be appreciated, however, that the data processing system 100 may be implemented in the form of any system including a processor and a memory that is capable of performing the functions described within this specification.

[0129] The memory elements 104 may include one or more physical memory devices such as, for example, local memory 108 and one or more bulk storage devices 110. The local memory may refer to random access memory or other non-persistent memory device(s) generally used during actual execution of the program code. A bulk storage device may be implemented as a hard drive or other persistent data storage device. The processing system 100 may also include one or more cache memories (not shown) that provide temporary storage of at least some program code in order to reduce the number of times program code must be retrieved from the bulk storage device 110 during execution.

[0130] Input/output (I/O) devices depicted as an input device 112 and an output device 114 optionally can be coupled to the data processing system. Examples of input devices may include, but are not limited to, a keyboard, a pointing device such as a mouse, or the like. Examples of output devices may include, but are not limited to, a monitor or a display, speakers, or the like. Input and/or output devices may be coupled to the data processing system either directly or through intervening I/O controllers.

[0131] In an embodiment, the input and the output devices may be implemented as a combined input/output device (illustrated in FIG. 8 with a dashed line surrounding the input device 112 and the output device 114). An example of such a combined device is a touch sensitive display, also sometimes referred to as a “touch screen display” or simply “touch screen”. In such an embodiment, input to the device may be provided by a movement of a physical object, such as e.g. a stylus or a finger of a user, on or near the touch screen display.

[0132] A network adapter 116 may also be coupled to the data processing system to enable it to become coupled to other systems, computer systems, remote network devices, and/or remote storage devices through intervening private or public networks. The network adapter may comprise a data receiver for receiving data that is transmitted by said systems, devices and/or networks to the data processing system 100, and a data transmitter for transmitting data from the data processing system 100 to said systems, devices and/or networks. Modems, cable modems, and Ethernet cards are examples of different types of network adapter that may be used with the data processing system 100.

[0133] As pictured in FIG. 8, the memory elements 104 may store an application 118. In various embodiments, the application 118 may be stored in the local memory 108, the one or more bulk storage devices 110, or apart from the local memory and the bulk storage devices. It should be appreciated that the data processing system 100 may further execute an operating system (not shown in FIG. 8) that can facilitate execution of the application 118. The application 118, being implemented in the form of executable program code, can be executed by the data processing system 100. e.g., by the processor 102. Responsive to executing the application, the data processing system 100 may be configured to perform one or more operations or method steps described herein.

[0134] In one aspect of the present invention, the data processing system 100 may represent control module for controlling the re-scan microscope system as described herein.

[0135] Various embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive. ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on the processor 102 described herein.

[0136] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising.” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0137] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.