Synchronous multiwavelength fluorescence system

• US 6,429,936 B1
• Filed: 08/06/1999
• Issued: 08/06/2002
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: C L Instruments Limited
• Original Assignee: C L Instruments Limited
• Inventors: Scaduto, Russell
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US09/369,526
• Time in Patent Office: 1,096 Days
• Field of Search: 356/417, 356/418, 250/458.1, 250/459.1, 250/461.1, 250/461.2
• US Class Current: 356/417
• CPC Class Codes: G01N 2021/6471 Special filters, filter wheel
• CPC Class Codes: G01N 21/6458 Fluorescence microscopy fluorescence microscopes per se G02B21/0076 and G02B21/16

Abstract

A multichannel system for synchronizing independently driven filter wheels. The system is comprised of a means for controlling operation of the system by providing appropriate instructions. A clock provides timing signals to assure that instructions are executed at the correct time. A device having a programmable memory with the ability to receive and transmit signals is in communication with the clock and the control means. This programmable memory device, in response to a signal from the control means executes a preselected program and transmits a signal in response to an instruction receive from the control means. Two assemblies, each comprised of a programmable motor controller, a motor driver and a motor are attached to an encoder and a filter wheel having a plurality of filters. The assemblies are connected to a power source. In response to the signal from the programmable memory device, each controller executes a preselected program that permits the controller to resolve the position of the encoder and hence the filter wheel with respect to an indexing means on the encoder at any instant in time. Thus the positions of the filter wheels can be synchronized with one another at any instant of time. In this manner, incident light of a single wavelength filtered by a first filter wheel and incident on a sample in a sample holder, for instance in a fluorescent microscope, can be synchronized with light emitted by the sample and filtered by a second filter wheel. The filtered, emitted light of a single wavelength provides characteristic information about activity within the sample.

Claims

1. A multichannel system for synchronizing independently driven filter wheels, comprising:

a means for controlling operation of the system by providing instructions;

a clock that provides timing signals;

a device with a programmable memory having the ability to receive and transmit signals, the device in communications with the clock and with the means for controlling operation of the system, the device receiving an instruction from the means for controlling operation of the system to execute a first preselected program and to transmit a signal in response to the instruction received from the means for controlling operation of the system;

at least two programmable motor controllers in communication with the clock to receive the timing signals, each being capable of being programmed to receive instructions from the device to run a second preselected program at a preselected time, the time determined by the timing signals from the clock;

at least two motor drivers, each motor driver connected to one of the at least two programmable motor controllers, each motor driver operating in response to an electrical signal from the controller;

a power source to provide power to the motor drivers;

a motor connected to each motor driver, each motor having a shaft;

an encoder rotatably mounted on each motor shaft, each encoder producing a plurality of pulses, and a means for indexing the position of the encoder on the motor shaft, the pulses being sent to the respective controller so that the respective controller can resolve the position of the encoder with respect to the indexing means; and

a filter disk rotatably mounted to each motor shaft having a plurality of filter positions, and having a fixed position in relation to the encoder mounted on the motor shaft, the position of each encoder being synchronized by the timing signal from the clock so that the plurality of filter positions on each filter disk are synchronized with respect to one another.

2. A system for synchronizing a pair of independently driven filter wheels, comprising:

a central processing unit that controls operation of the system;

a clock that provides timing signals;

a programmable logic device with a programmable memory having the ability to receive and transmit signals, the logic device in communication with the clock and with the central processing unit, the logic device receiving an instruction from the central processing unit to execute a first preselected program and transmitting a signal in response to the instruction received from the central processing unit;

a first assembly comprised of a first programmable motor controller, a first motor driver, a first motor, a first encoder and a first filter wheel, the first programmable motor controller in communication with the clock to receive the timing signals and capable of being programmed to receive instructions from the logic device to run a second preselected program at a preselected time, the time determined by the timing signals from the clock, the first motor driver connected to the first programmable motor controller and operating in response to an electrical signal from the first motor controller, the first motor having a shaft and connected to the first motor driver, the first encoder rotatably mounted on the shaft of the first motor, the first encoder being further comprised of a disk having a plurality of slots, a light source positioned on the first side of the disk producing a beam of light incident on the disk as the disk is rotated on the shaft, a detector positioned on a second side of the disk that detects pulses of light transmitted through the slots of the rotating disk and digitizes the pulses, and a means for indexing the position of the first encoder on the shaft of the first motor, the digitized pulses being sent to the first controller so that the first controller can resolve the position of the first encoder with respect to the indexing means and the first filter wheel rotatably mounted to the shaft of the first motor and having a plurality of filter positions, the first filter wheel having a fixed position in relation to the first encoder on the shaft of the first motor, the position of the first encoder being determined by the shaft rotational speed, the timing signal from the clock and the position of the encoder with respect to the indexing pulse, so that one of the plurality of filters on the first filter disk can be positioned in a preselected position at a preselected time;

a second assembly comprised of a second programmable motor controller, a second motor driver, a second motor, a second encoder and a second filter wheel, the second programmable motor controller in communication with the clock to receive the timing signals and capable of being programmed to receive instructions from the logic device to run a second preselected program at a preselected time, the time determined by the timing signals from the clock, the second motor driver connected to the second programmable motor controller and operating in response to an electrical signal from the second motor controller, the second motor having a shaft and connected to the second motor driver, the second encoder rotatably mounted on the shaft of the second motor, the second encoder being further comprised of a disk having a plurality of slots, a light source positioned on a first side of the disk producing a beam of light incident on the disk as the disk is rotated on the shaft, a detector positioned on a second side of the disk that detects pulses of light transmitted through the slots of the rotating disk and digitizes the pulses, and a means for producing an indexing pulse for determining the initial position and subsequent positions of the second encoder on the shaft of the second motor, the digitized pulses being sent to the second controller so that the second controller can resolve the position of the second encoder with respect to the indexing means, and the second filter wheel rotatably mounted to the shaft of the second motor and having a plurality of filter positions, the second filter wheel having a fixed position in relation to the second encoder on the shaft of the second motor, the position of the second encoder being determined by the shaft rotational speed, the timing signal from the clock and the position of the second encoder with respect to the indexing pulse, so that one of the plurality of filters on the second filter disk can be positioned in a preselected position at the preselected time corresponding to the preselected position of the one of the filters on the first filter disk at the preselected time; and

a power source to provide power to the motor drivers.

3. The system of claim 2 wherein the clock operates at a speed of at least about 100 kilohertz.

4. The system of claim 3 wherein the clock operates at a speed of about 1.8 megahertz.

5. The system of claim 2 wherein the first encoder disk and the second encoder disk each include a ring having a plurality of radial slots.

6. The system of claim 5 wherein the first encoder disk and the second encoder disk are further comprised of a pair of concentric rings, a first ring having a smaller diameter than a second ring, each ring having a plurality of radial slots, the radial slots of the first ring not being co-radial with the slots of the second ring.

7. The system of claim 6 wherein each ring of each encoder has 512 radial slots.

8. The system of claim 2 wherein the first filter wheel includes 8 filter positions and 8 filters.

9. The system of claim 2 wherein the second filter wheel includes 8 filter positions and 8 filters.

10. The system of claim 8 wherein each of the filters produces a single wavelength of light different than the wavelengths of the other filters.

11. The system of claim 9 wherein each of the filters produces a single wavelength of light different than the wavelengths of the other filters.

12. A fluorometer for observing activity of a reaction occurring in a sample, comprising:

a central processing unit to control the operations of the microscope;

a clock that provides timing signals;

a programmable logic device the receives instructions from the central processing unit and timing signals from the clock, and that provides instructions;

a light source that produces a broadband beam of light;

an infrared filter to remove, by filtering, light from the infrared spectrum;

a first focusing lens to focus the filtered light;

an excitation assembly upon which the filtered light is focused, the excitation assembly comprised of a first programmable motor controller, a first motor driver, a first motor, a first encoder and a first filter wheel, the first programmable motor controller in communication with the clock to receive the timing signals and programmed to receive instructions from the programmable logic device to run a second preselected program at a preselected time, the time determined by the timing signals from the clock, the first motor driver connected to the first programmable motor controller and operating in response to an electrical signal from the first motor controller, the first motor having a shaft and connected to the first motor driver, the first encoder rotatably mounted on the shaft of the first motor, the first encoder being further comprised of a disk having a plurality of slots, a light source positioned on the first side of the disk producing a beam of light incident on the disk as the disk is rotated on the shaft, a detector positioned on a second side of the disk that detects pulses of light transmitted through the slots of the rotating disk and digitizes the pulses, and a means for indexing the position of the first encoder on the shaft of the first motor, the digitized pulses being sent to the first controller so that the first controller can resolve the position of the first encoder with respect to the indexing means and the first filter wheel rotatably mounted to the shaft of the first motor and having a plurality of filter positions, the first filter wheel having a fixed position in relation to the first encoder on the shaft of the first motor, the position of the first encoder being determined by the shaft rotational speed, the timing signal from the clock and the position of the encoder with respect to the indexing pulse, causing a preselected one of the plurality of filters on the first filter disk to be positioned in a preselected position at a preselected time so that infrared-filtered light from the focusing lens is filtered by the one preselected filter at the preselected time to produce light of a single wavelength;

a first light guide to receive, guide and transmit the light of the single wavelength from the filter;

a collimating lens to receive the light transmitted from the light guide and collimate the light;

a sample chamber that receives the single wavelength light, directs the single wavelength of light onto the sample, thereby exciting the sample that acts as a second source of light as it is emits light as it decays;

a second focusing lens to focus the light emitted by the sample;

a second light guide to receive, guide and transmit the light emitted from the sample;

an emission assembly to receive light from the light guide emitted by the sample, the emission assembly comprised of a second programmable motor controller, a second motor driver, a second motor, a second encoder and a second filter wheel, the second programmable motor controller in communication with the clock to receive the timing signals and capable of being programmed to receive instructions from the logic device to run a second preselected program at a preselected time, the time determined by the timing signals from the clock, the second motor driver connected to the second programmable motor controller and operating in response to an electrical signal from the second motor controller, the second motor having a shaft and connected to the second motor driver, the second encoder rotatably mounted on the shaft of the second motor, the second encoder being further comprised of a disk having a plurality of slots, a light source positioned on a first side of the disk producing a beam of light incident on the disk as the disk is rotated on the shaft, a detector positioned on a second side of the disk that detects pulses of light transmitted through the slots of the rotating disk and digitizes the pulses, and a means for producing an indexing pulse for determining the initial position and subsequent positions of the second encoder on the shaft of the second motor, the digitized pulses being sent to the second controller so that the second controller can resolve the position of the second encoder with respect to the indexing means, and the second filter wheel rotatably mounted to the shaft of the second motor and having a plurality of filter positions, the second filter wheel having a fixed position in relation to the second encoder on the shaft of the second motor, the position of the second encoder being determined by the shaft rotational speed, the timing signal from the clock and the position of the second encoder with respect to the indexing pulse, so that one of the plurality of filters on the second filter disk can be positioned in a preselected position at the preselected time corresponding to the preselected position of the one of the filters on the first filter disk at the preselected time causing a preselected one of the plurality of filters on the second filter disk to be positioned in a preselected position at the preselected time so that light emitted by the sample is filtered by the preselected one filter at the preselected time to produce a second light of a single wavelength;

a third focusing lens to focus the second single wavelength of light from the emission assembly; and

means for observing the light from the third focusing lens.

13. The fluorometer of claim 12 wherein the means for observing includes an optical objective.

14. The fluorometer of claim 12 further including a photomultiplier tube to amplify the second single wavelength of light from the third focusing lens and convert the light to a signal.

15. The fluorometer of claim 14 wherein the means for observing includes a storage device to store the signal from the photomultiplier tube for later observation.

16. The fluorometer of claim 12 wherein the means for observing the light includes a CCD camera for observing the light and a display for visual display of the signal from the camera.

17. The fluorometer of claim 16 further including means for storing the signal received by the display from the camera.

18. The fluorometer of claim 12 wherein the sample chamber is a fluorescent microscope that additionally includes a dichroic mirror and an objective, the dichroic mirror directing the received single wavelength of light through an objective onto the sample.

19. A method for synchronizing at least a first and a second independently operated filter wheel assembly, each assembly including an associated motor and motor controller, used in conjunction with a light source to excite a sample and a detector to observe rapidly occurring activity in the sample, comprising the steps of:

placing the sample in an observation chamber;

providing a signal from a central control unit to move the first filter wheel assembly and the second filter wheel assembly to preselected initial positions;

providing light from a light source;

providing a signal from the control unit to the motor controllers to load a preselected program into a memory of the motor controller;

then

providing a signal from the control unit to the motor controllers to simultaneously execute the preselected program, thereby moving the filter wheel assemblies by activating the motors to predetermined locations at predetermined times;

transmitting light of a predetermined wavelength through one of a plurality of filters on the first filter wheel assembly onto the sample, thereby exciting the sample;

detecting light emitted by the sample;

directing the detected emitted light from the sample onto the second filter wheel assembly to filter light from the sample;

observing light having a wavelength characteristic of a reaction on-going in the sample transmitted through one of a plurality of filters on the second filter wheel assembly at a preselected time.

20. A method for observing a sample in fluorometer using at least a first and a second independently operated filter wheel assembly, each assembly being synchronized in operation with the other and including an associated motor and motor controller, used in conjunction with a light source to excite a samples and a detector to observe rapidly occurring activity in the sample, comprising the steps of:

placing the sample in an observation chamber;

providing a signal from a central control unit to move the filter wheel assemblies to preselected initial positions;

providing light from a light source;

providing a signal from the control unit to the motor controllers to load a preselected program into a memory of the motor controller;

then

providing a signal from the control unit to the motor controllers to simultaneously execute the preselected program, thereby moving the filter wheel assemblies by activating the motors to predetermined locations at predetermined times;

transmitting light of a predetermined wavelength through one of a plurality of filters on the first filter wheel assembly onto the sample, thereby exciting the sample;

detecting light emitted by the sample;

directing the detected emitted light from the sample onto the second filter wheel assembly to filter light from the sample;

observing light having a wavelength characteristic of a reaction on-going in the sample transmitted through one of a plurality of filters on the second filter wheel at a preselected time.

21. The method of claim 20 wherein the step of placing the sample in an observation chamber includes placing the sample in a fluorescent microscope.