WO2013003469A2

WO2013003469A2 - Method and apparatus for automated indexing of pluralities of filter arrays

Info

Publication number: WO2013003469A2
Application number: PCT/US2012/044411
Authority: WO
Inventors: Michael SCARDINA; James Masciotti; Wael HAZIN; Frederick E. Morgan
Original assignee: Bioscan, Inc.
Priority date: 2011-06-27
Filing date: 2012-06-27
Publication date: 2013-01-03
Also published as: WO2013003469A3

Abstract

A system comprises a base defining a plane perpendicular to an axis, a set of elements mounted on a surface of the base parallel to the axis, and a drive assembly in communication with the base. Each element is positionable within a respective guide channel of a mechanical structure containing optical detectors, and each element includes a plurality of sites generally parallel to the axis for securing an optical filter. The drive assembly is configured to move the base along the axis to position a respective site of each element in the set of elements in the respective guide channel relative to an optical detector.

Description

METHOD AND APPARATUS FOR AUTOMATED INDEXING OF

PLURALITIES OF FILTER ARRAYS

TECHNICAL FIELD

The present inventive concepts generally relate to methods and apparatuses for automated indexing of filter arrays, and more particularly, to an optical imaging system employing an automated linear optical filter changing system for collimated photodetectors.

BACKGROUND

Multispectral imaging is a popular technique for capturing image information across different wavelengths, and can be performed by sequentially acquiring image data using filters of varying wavelength bands. For example, filters having varying wavelength bands can be positioned in front of image sensors or detectors to capture image data at specific frequency bands.

One application of multispectral imaging is in- vivo optical imaging. In- vivo optical imaging involves imaging the fluorescent or bioluminescent light that exits small laboratory animals such as mice. This light that exits the animal is usually due to some optical probe, tag, or labeled cells, which allow researchers to detect and study biological processes or disease states. For example, multispectral imaging can be performed on image sources that emit fluorescent or bioluminescent light at different wavelengths, which can be performed to remove unwanted spectral components from an image or to acquire additional information about the location or disposition of the source. Generally, multispectral imaging devices include filter wheels or other types of devices, such as tunable filters, that are used in conjunction with a camera to detect light at different wavelengths. These filter wheels have some advantages in terms of cost and performance over tunable filters, but tend to occupy more space.

One limitation of traditional in-vivo optical imaging, is that the scattering and absorption that occurs in tissue limits the direct usefulness of data that is collected because the amount of light detected exiting the surface of the tissue is not only dependant on the strength of the source emitting light inside tissue, but is also dependant on the size, and location of the source as well as the optical properties. To overcome this limitation and in order to obtain 3D images, tomographic imaging techniques are often employed. Tomographic imaging techniques frequently involve detecting light/radiation at multiple detectors or sensors positioned around the image source or subject. In order to obtain high sensitivity and resolution images, it is often desirable for these detectors and sensors to be closely spaced. However, it can be difficult to package these detectors and sensors closely together due to the space constraints of the devices, especially when using a filter wheel.

SUMMARY

Various methods and apparatuses for automated indexing of filter arrays are described herein. These methods and apparatuses can provide, for example, a filter changing system that can be used with an array of detectors that are closely spaced, and/or a filter changing system for an array of detectors which are closely spaced and collecting light from different directions. In some embodiments, the methods and apparatuses are configured to automatically select, under computer control, a specific filter from linear arrays of filters that are positioned in front of detectors which are closely spaced.

In one aspect, a system comprises: a base defining a plane perpendicular to an axis; a set of elements mounted on a surface of the base parallel to the axis, each element positionable within a respective guide channel of a mechanical structure containing optical detectors, each element including a plurality of sites generally parallel to the axis for securing an optical filter; and a drive assembly in communication with the base, the drive assembly configured to move the base along the axis to position a respective site of each element in the set of elements in the respective guide channel relative to an optical detector.

In some embodiments, the elements are mounted about a circular perimeter of the base. In some embodiments, the filters sample at different angles with respect to an imaging area within an imaging chamber.

In some embodiments, the filters are positioned normal to a reflected, transmitted, and/or emitted beam.

In some embodiments, the filters permit different wavelengths of light to reach the optical detectors.

In some embodiments, the elements surround an imaging chamber.

In some embodiments, the system further comprises a plurality of optical detectors positioned relative to the sites.

In some embodiments, the mechanical structure is a collimator plate in a plane parallel to the base plane.

In some embodiments, the drive assembly is a motor driving three or more mounting points.

In some embodiments, the three or more mounting points are screw-drives.

In some embodiments, the drive assembly includes a dummy pulley and/or an active pulley for each drive point. In some embodiments, the system further comprises a second base with a second set of elements.

In some embodiments, the second base moves in a direction parallel to the axis and either in an opposite direction or the same direction as the (first) base.

In some embodiments, the mechanical structure defines a hollow inner area that is in the shape of a polygon, circle, or other general shape and is either open or closed.

In another aspect, an apparatus comprises: a base defining a plane perpendicular to an axis; a plurality of linear stages parallel to the axis and positioned relative to the base; a drive motor in communication with the plurality of linear stages, the drive motor actuating each of the plurality of linear stages to move the base and the plane along the axis.

In some embodiments, the linear stages are screw-drives and the drive motor drives a belt that turns each of the screw-drives.

In another aspect, a method comprises: providing a filter array comprising a plurality of filter holders disposed about a surface of a base defining a first plane perpendicular to the plurality of filter holders, each filter holder defining a plurality of sites linearly indexed along a length of each filter holder for positioning one or more filters, each site of the plurality of sites of a filter holder generally coplanar with a corresponding site of the other filter holders in the plurality of filter holders to form a plurality of indexed planar positions; and controllably moving the base along an axis parallel to the plurality of filter holders to position at least one of the plurality of indexed planar stages within a plurality of channel guides of a collimator apparatus relative to a plurality of optical detectors.

In some embodiments, the plurality of filters in an indexed planar stage filter the same wavelengths of light.

In some embodiments, the plurality of filters in an indexed planar stage filter different wavelengths of light.

In another aspect, an optical imaging system comprises: an imaging chamber; a light source for illuminating an interior of the imaging chamber; a plurality of detectors disposed about a perimeter of the imaging chamber; a structure defining a plurality of channels disposed relative to the detectors for illumination reflected, transmitted, or emitted from the subject and passing the collimated illumination to the plurality of detectors, the structure including an opening within at least a subset of the plurality of channels for passing a filter holder therethrough; and an array of linear filter holders each containing a plurality of filters, the array moveable relative to the structure to pass the filter holders through respective openings of the subset in response to actuation by a drive mechanism for positioning the filter holders adjacent to the plurality of detectors. In some embodiments, the illumination is collimated illumination.

In some embodiments, the collimated illumination is from a laser source.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of embodiments of the present inventive concepts will be apparent from the more particular description of preferred embodiments, as illustrated in the accompanying drawings in which like reference characters refer to the same elements throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the preferred embodiments.

FIG. 1 is a perspective view of an imaging device comprising two independent and movable linear filter ring assemblies, in accordance with embodiments of the present inventive concepts;

FIG. 2 is a perspective sectioned view of an optical collimator with features for collimation of light, in accordance with embodiments of the present inventive concepts;

FIGs. 3-11 are top, bottom, and side perspective views of an electromechanical drive assembly for controlling the position of movable linear filter rings, in accordance with embodiments of the present inventive concepts;

FIG. 12 is a sectioned view of the imaging device shown in FIG. 1 , which illustrates a collimator and two independent linear filter ring assemblies, in accordance with other embodiments of the present inventive concepts; and

FIGs. 13-14 are views of an individual filter holder, in accordance with other embodiments of the present inventive concepts. DETAILED DESCRIPTION OF EMBODIMENTS

It will be understood that, although the terms first, second, third etc. may be used herein to describe various limitations, elements, components, regions, layers and/or sections, these limitations, elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one limitation, element, component, region, layer or section from another limitation, element, component, region, layer or section. Thus, a first limitation, element, component, region, layer or section discussed below could be termed a second limitation, element, component, region, layer or section without departing from the teachings of the present application.

It will be further understood that when an element is referred to as being "on" or "connected" or "coupled" to another element, it can be directly on or above, or connected or coupled to, the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly on" or "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). When an element is referred to herein as being "over" another element, it can be over or under the other element, and either directly coupled to the other element, or intervening elements may be present, or the elements may be spaced apart by a void or gap.

FIG. 1 is a perspective view of an imaging device comprising two independent and movable linear filter ring assemblies. The imaging device 100 shown comprises a mechanical assembly including an upper linear filter ring assembly 120, a collimator 130 and a lower linear filter ring assembly 150. The imaging device 100 is constructed and arranged to image a subject or specimen positioned within an imaging volume IV. For example, the subject or specimen can be positioned within the inner bore IB of the collimator 130.

The collimator 130 is mounted within the imaging device 100, and includes an array of light collimating channels (133 of FIG. 2) arranged about an inner perimeter of the collimator 130. In some embodiments, the collimator 130 includes an array of forty-eight light collimating channels. During operation of the imaging device 100, light enters each of these light collimating channels through entrance apertures (134 of FIG. 2) arranged about an inner perimeter of the collimator 130. The inner perimeter of the collimator 130 defines the inner bore IB. The imaging device 100 further includes an array of electronic circuit boards 140, which are positioned about the outer perimeter of the collimator 130. The electronic circuit boards 140 include photodetectors and supporting electronics for collecting collimated light exiting the collimator 130. In some embodiments, the imaging device 100 includes an array of twelve electronic circuit boards 140 including a total of forty-eight photodetectors (four photodetectors per board).

The upper linear filter ring assembly 120 includes a first filter ring 114 and first filter holders 110. The first filter holders 110 are coupled to the first filter ring 114, for example, by screw fasteners. In some embodiments, the upper linear filter ring assembly 120 includes twenty four individual first filter holders 110, and each first filter holder can include, for example, sixteen separate filters. As described below, the upper linear filter ring assembly 120 can be translated along an axis 102 perpendicular to a surface of the base 101 of the imaging device 100 such that the first filter holders 110 move relative to the collimator 130. This vertical motion allows for any of the up to sixteen filters in each of the first linear filter holders 110 to be positioned in the optical path of collimated light that exits the exit apertures (135 of FIG. 2) of the light collimating channels (133 of FIG. 2). This collimated light then passes through filters of the first filter holders 110 before being projected onto the photodetectors of the electronic circuit boards 140.

The lower linear filter ring assembly 150 includes a second filter ring 154 and second filter holders 111. The second filter holders 111 are coupled to the second filter ring 1 4, for example, by screw fasteners. In some embodiments, the lower linear filter ring assembly 150 includes twenty four individual second filter holders 111, and each second filter holder can include, for example, sixteen separate filters. As described below, the lower liner filter ring assembly 150 can be translated along the axis 102 perpendicular to the surface of the base 101 of the imaging device 100 such that the second filter holders 111 move relative to the collimator 130. This vertical motion allows for any of the up to sixteen filters in each of the second linear filter holders 111 to be positioned in the optical path of collimated light that exits the exit apertures (135 of FIG. 2) of the light collimating channels (133 of FIG. 2). This collimated light then passes through filters of the first filter holders 110 before being projected onto the photodetectors of the electronic circuit boards 140.

FIG. 2 is a perspective sectioned view of an optical collimator with features for collimation of light. The inner perimeter of the collimator 130 defines the inner bore IB of the imaging device 100. The collimator 130 includes an array of collimating channels 133 arranged radially about the inner perimeter of the collimator 130. In some embodiments, the collimator 130 includes an array of forty-eight light collimating channels 133 (equal to the number of first and second filter holders 110, 111). Each collimating channel 133 includes an entrance aperture 134 positioned at a first end of the collimating channel 133 and an exit aperture 135 positioned at a second end of the collimating channel 133. The collimator 130 further includes an array of filter holder guide channels 132 that are aligned with the exit apertures 135 of the light collimating channels 133. The filter holder guide channels 132 accept the first and second linear filter holders 110, 111, and align filers of the first and second linear filter holders 110, 111 with the light collimating channels of the collimator 130.

The collimator 130 is constructed and arranged to guide collimated light to the photodetectors of the electronic circuit boards 140. For example, light from the inner bore IB of the imaging device 100 enters the light collimating channels 133 through the entrance apertures 134 of the collimator 130 and travels through the light collimating channels 133. The light exits the exit apertures 135 of the collimator 130 and projects across the filter holder guide channels 132. When first and second filter holders 110, 111 are placed in a vertical orientation in the filter holder guide channels 132, the light can be configured to pass through a filter of the first and second filter holders 110, 11 1. Light passing through the filters of the first and second filter holders 110, 111 exit guide features 131 of the collimator.

FIGs. 3-11 are top, bottom, and side perspective views of an electromechanical drive assembly for controlling the position of movable linear filter rings. FIGs. 3-6 illustrate a first drive mechanism for controlling the vertical motion of the lower linear filter ring assembly 150, and FIGs. 7-1 1 illustrate a second drive mechanism for controlling the vertical motion of the upper liner filter ring assembly 120.

The first drive mechanism includes a fixed mounting plate 170 that is rigidly mounted to the imaging device 100 via standoffs 180. A motor 160 is attached to the mounting plate 170 and drives a timing belt 165. The timing belt 165 drives a series of pulleys 162 that are arranged around the outside circumference of the imaging volume IV so as not to interfere with or occupy imaging volume IV. The first drive mechanism also includes a compact lead screw drive mechanism, which includes, for example, three lead screws 163 with rotary nuts 164 that are rigidly attached to a traveling plate 166. As the motor 160 drives the belt 165 in either rotational direction, the belt in turn rotates the three lead screws 163, which causes the rotary nuts 164 and thus the traveling plate 166 to move in a vertical direction. The lower linear filter ring assembly 150 is rigidly attached to the traveling plate 166 and thus the entire lower linear filter ring assembly 150 is able to move in the vertical direction such that the filters of the array of linear filter holders 1 1 1 are able to be aligned with the exit apertures 135 of the collimator 130.

The second drive mechanism includes a fixed mounting plate 190 that is rigidly mounted to the imaging device 100. A motor 192 is attached to the mounting plate 190 and drives a timing belt 193. The timing belt 193 drives a series of pulleys 197 that are arranged around the outside circumference of the imaging volume IV so as not to interfere with or occupy the imaging volume IV. The second drive mechanism also includes a compact lead screw drive mechanism, which includes, for example, three lead screws 196 with rotary nuts 198. In this embodiment, the rotary nuts 1 8 are rigidly attached to the pulleys 197 that are driven by the timing belt 193. The rotary nuts 198 and pulleys 197 are seated in bearings 200, which are captured between the fixed mounting plate 190 and sub mounting plate 191. The fixed mounting plate 190 and the sub mounting plate 191 are coupled via standoffs 201. The lead screws 196 are attached to a traveling plate 195. As the motor 192 drives the belt 193 in either rotational direction, the belt in turn rotates the pulleys 197 and thus the three rotary nuts 198 around the lead screws 196. This causes the lead screws 196 and the traveling plate 195 to move in a vertical direction. The upper linear filter ring assembly 120 is rigidly attached to the traveling plate 195 and thus the entire upper linear filter ring assembly 120 is able to move the vertical direction such that the filters of the array of linear filter holders 110 are able to be aligned with the exit apertures 135 of the collimator 130.

FIG. 12 is a sectioned view of the imaging device shown in FIG. 1 , and illustrated a sectioned view of the collimator 130. In some embodiments, each of the upper linear filter holders 110 can include up to sixteen separate filters 144, which are positioned in filter slots 142. Similarly, each of the lower linear filter holders 111 can include up to sixteen separate filters 143, which are positioned in the filter slots 141. As described above, the upper linear filter holders 110 are able to be translated in a vertical direction such that a desired filter 144 can be aligned with the light collimating channel exit aperture 135 of the collimator 130. Light from the light collimating channel 133 can be projected through the filter 144 and onto the photodetectors on the electronic circuit boards 140. In this same manner, the lower linear filter holders 111 are able to be translated in a vertical direction such that a desired filter 144 can be aligned with the light collimating channel exit aperture 130 of the collimator 130.

FIGs. 13-14 are views of an individual filter holder. The first and second linear holders 110, 111 include filter slots 141 for capturing individual filters 143. For example, in some embodiments the linear filter holders 110, 111 each include, for example, sixteen filter slots. Each filter slot 141 can capture an individual filter 143. However, in some embodiments, some of the filter slots 141 are left empty.

While the present inventive concepts have been particularly shown and described above with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art, that various changes in form and detail can be made without departing from the spirit and scope of the present inventive concepts described and defined by the following claims.

Claims

CLAIMS What is claimed is:

1. A system comprising:

a base defining a plane perpendicular to an axis;

a set of elements mounted on a surface of the base parallel to the axis, each element positionable within a respective guide channel of a mechanical structure containing optical detectors, each element including a plurality of sites generally parallel to the axis for securing an optical filter; and

a drive assembly in communication with the base, the drive assembly configured to move the base along the axis to position a respective site of each element in the set of elements in the respective guide channel relative to an optical detector.

2. The system of claim 1 , wherein the elements are mounted about a circular perimeter of the base.

3. The system of any of claims 1-2, wherein the filters sample at different angles with respect to an imaging area within an imaging chamber.

4. The system of any of claims 1-3, wherein the filters are positioned normal to a reflected, transmitted, and/or emitted beam.

5. The system of any of claims 1-4, wherein the filters permit different wavelengths of light to reach the optical detectors.

6. The system of any of claims 1-5, wherein the elements surround an imaging chamber.

7. The system of any of claims 1-6 further comprising a plurality of optical detectors positioned relative to the sites.

8. The system of any of claims 1-7, wherein the mechanical structure is a collimator plate in a plane parallel to the base plane.

9. The system of any of claims 1-8, wherein the drive assembly is a motor driving three or more mounting points.

10. The system of any of claims 1-9, wherein the three or more mounting points are screw- drives.

11. The system of any of claims 1-10, wherein the drive assembly includes a dummy pulley and/or an active pulley for each drive point.

12. The system of any of claims 1-11, further comprising a second base with a second set of elements.

13. The system of claim 12, wherein the second base moves in a direction parallel to the axis and either in an opposite direction or the same direction as the (first) base.

14. The system of any of claims 1-13, wherein the mechanical structure defines a hollow inner area that is in the shape of a polygon, circle, or other general shape and is either open or closed.

15. An apparatus comprising:

a base defining a plane perpendicular to an axis;

a plurality of linear stages parallel to the axis and positioned relative to the base;

a drive motor in communication with the plurality of linear stages, the drive motor actuating each of the plurality of linear stages to move the base and the plane along the axis.

16. The apparatus of claim 15, wherein the linear stages are screw-drives and the drive motor drives a belt that turns each of the screw-drives.

17. A method comprising:

providing a filter array comprising a plurality of filter holders disposed about a surface of a base defining a first plane perpendicular to the plurality of filter holders, each filter holder defining a plurality of sites linearly indexed along a length of each filter holder for positioning one or more filters, each site of the plurality of sites of a filter holder generally coplanar with a corresponding site of the other filter holders in the plurality of filter holders to form a plurality of indexed planar positions; and controllably moving the base along an axis parallel to the plurality of filter holders to position at least one of the plurality of indexed planar stages within a plurality of channel guides of a collimator apparatus relative to a plurality of optical detectors.

18. The method of claim 17, wherein the plurality of filters in an indexed planar stage filter the same wavelengths of light.

19. The method of claim 17, wherein the plurality of filters in an indexed planar stage filter different wavelengths of light.

20. An optical imaging system comprising:

an imaging chamber;

a light source for illuminating an interior of the imaging chamber;

a plurality of detectors disposed about a perimeter of the imaging chamber;

a structure defining a plurality of channels disposed relative to the detectors for illumination reflected, transmitted, or emitted from the subject and passing the collimated illumination to the plurality of detectors, the structure including an opening within at least a subset of the plurality of channels for passing a filter holder therethrough; and

an array of linear filter holders each containing a plurality of filters, the array moveable relative to the structure to pass the filter holders through respective openings of the subset in response to actuation by a drive mechanism for positioning the filter holders adjacent to the plurality of detectors.

21. The system of claim 20, wherein the illumination is collimated illumination.

22. The system of claim 21 , wherein the collimated illumination is from a laser source.