Image synchronization without input clock and data transmission clock in a pulsed fluorescence imaging system

1. A system comprising:

an emitter comprising a plurality of electromagnetic sources configured to emit a plurality of pulses of electromagnetic radiation;

an image sensor comprising a pixel array that detects electromagnetic radiation and reads out a plurality of exposure frames according to a sensor cycle that comprises a plurality of variable blanking periods and a plurality of readout periods;

a plurality of bidirectional data pads on the image sensor for outputting image data and receiving configuration data; and

a controller in electronic communication with the image sensor and the emitter;

wherein the configuration data received by the image sensor comprises timing data for reading out the plurality of exposure frames according to the sensor cycle;

wherein a duration of each of the plurality of variable blanking periods of the image sensor is adjustable such that the sensor cycle comprises two or more blanking periods having a different duration;

wherein at least one of the plurality of electromagnetic sources of the emitter is a fluorescence source tuned to pulse electromagnetic radiation within a waveband from about 770 nm to about 795 nm; and

wherein each of the plurality of variable blanking periods is adjustable based on an amount of energy emitted by the emitter during a pulse duration.

2. The system of claim 1 , further comprising:

an oscillator disposed in the controller; and

a frequency detector in electronic communication with the controller to control a clock frequency of the image sensor in response to signals from the controller that correspond to the frequency of the oscillator.

3. The system of claim 1 , wherein electronic communication through each of the plurality of bidirectional pads is performed in defined phases comprising:

a rolling readout phase during which image data is output from the image sensor through the plurality of bidirectional pads to the controller;

a service line phase during which non-image data is output from the image sensor through the plurality of bidirectional pads to the controller; and

a configuration phase during which image sensor configuration data is received by the image sensor from the controller through the plurality of bidirectional pads;

wherein image sensor data output lines are reversed during the configuration phase; and

wherein a clock data recovery circuit is unlocked from an oscillator disposed in the controller when the image sensor data output lines are reversed.

4. The system of claim 3 , wherein clock signal data is transmitted during the service line phase and the configuration phase and is not transmitted during the rolling readout phase.

5. The system of claim 1 , wherein the image sensor does not comprise a dedicated input synchronization clock pad such that a total number of data pads in the image sensor is reduced.

6. The system of claim 1 , further comprising an oscillator disposed in the controller for providing a reference clock frequency to synchronize incoming data received from the image sensor.

7. The system of claim 1 , further comprising at least one transition within pixel serial data created by the pixel array of the image sensor, wherein the pixel serial data is replaced in the pixel array according to synchronization determined by clock signal data.

8. The system of claim 1 , further comprising:

a phase lock loop (PLL) comprising PLL image sensor blocks and PLL controller blocks;

data lines electrically connecting the PLL image sensor blocks and the PLL controller blocks; and

configuration lines electrically connecting the PLL image sensor blocks and the PLL controller blocks;

wherein an oscillator disposed in the controller and a data recovery circuit are used to lock on to incoming data received by the controller from the image sensor.

9. The system of claim 1 , wherein the controller instructs the emitter to emit the plurality of pulses of electromagnetic radiation according to a variable pulse cycle; and

wherein the variable pulse cycle of the emitter is synchronized with the sensor cycle of the image sensor such that the pixel array detects the electromagnetic radiation and reads out data for generating an exposure frame in response to each pulse of electromagnetic radiation emitted by the emitter.

10. The system of claim 1 , wherein the image sensor reads out data during the plurality of readout periods to output the plurality of exposure frames;

wherein the pixel array accumulates electromagnetic radiation during at least a portion of the plurality of variable blanking periods; and

wherein the controller synchronizes operations of the emitter and the image sensor such that the emitter cycles on at least one of the plurality of electromagnetic sources during at least the portion of the plurality of blanking periods; and

wherein the controller synchronizes operations of the emitter and the image sensor such that the emitter cycles off each of the plurality of electromagnetic sources during the plurality of variable blanking periods of the sensor cycle.

11. The system of claim 1 , wherein two more of the plurality of exposure frames are combined to generate an overlay frame comprising color imaging data and fluorescence imaging data.

12. The system of claim 1 , further comprising:

a voltage-controlled oscillator;

a phase lock loop based on a charge pump for driving the voltage-controlled oscillator; and

a phase lock loop based on a digital-to-analog converter for driving the voltage-controlled oscillator.

13. The system of claim 1 , wherein the pixel array detects the electromagnetic radiation and outputs data for one exposure frame subsequent to one pulse duration.

14. The system of claim 1 , wherein the controller instructs the emitter to actuate the plurality of electromagnetic sources according to a variable pulse cycle comprising a plurality of independent pulse durations, and wherein the controller instructs the emitter to pulse two or more wavelengths simultaneously or independently during at least one pulse duration of the plurality of independent pulse durations.

15. The system of claim 1 , wherein the plurality of electromagnetic sources of the emitter comprises:

a visible source tuned to pulse electromagnetic radiation within a visible waveband of the electromagnetic spectrum; and

the fluorescence source;

wherein the pixel array detects the electromagnetic radiation and outputs data for generating a fluorescence exposure frame in response to the fluorescence source pulsing the electromagnetic radiation within the near-infrared waveband.

16. The system of claim 15 , wherein the fluorescence source is finely tuned to emit electromagnetic radiation only within the waveband from about 770 nm to about 795 nm.

17. The system of claim 15 , wherein the controller is configured to:

provide the fluorescence exposure frame to a corresponding system that determines one or more of an identity or a location of a tissue structure within a scene based on the data for the fluorescence exposure frame;

receive one or more of the identity or the location of the tissue structure from the corresponding system;

generate an overlay frame comprising an overlay highlighting the location of the tissue structure overlaid on a color image frame depicting the scene to indicate the location of the tissue structure within the scene.

18. The system of claim 17 , wherein the tissue structure comprises one or more of a nerve, a ureter, a blood vessel, an artery, a blood flow, or a tumor.

19. The system of claim 1 , wherein each of the plurality of variable blanking periods of the sensor cycle corresponds to a time between a readout of a last row of active pixels in the pixel array and a beginning of a next subsequent readout of active pixels in the pixel array; and

wherein the duration of each of the plurality of variable blanking periods is adjustable to ensure sufficient exposure in a corresponding exposure frame read out by the image sensor.

20. The system of claim 1 , wherein the two or more blanking periods having the different duration comprises a first blanking period having a first duration and a second blanking period having a second duration;

wherein the emitter pulses a first emission during the first blanking period;

wherein the emitter pulses a second emission during the second blanking period; and

wherein the first duration and the second duration are determined at least in part based on relative intensities of the first emission and the second emission.

21. The system of claim 1 , wherein the image sensor comprises a first image sensor and a second image; and

wherein simultaneous outputs from the first image sensor and the second image sensor are utilized to generate a three-dimensional image.

22. The system of claim 1 , wherein the emitter pulses the plurality of pulses of electromagnetic radiation according to a variable pulse cycle, and wherein the emitter repeats the variable pulse cycle at a speed sufficient for generating a video stream comprising color imaging data and fluorescence imaging data.

23. The system of claim 1 , wherein the emitter pulses the plurality of pulses of electromagnetic radiation according to a variable pulse cycle comprising two or more different wavelengths of electromagnetic radiation:

wherein the controller adjusts the variable pulse cycle based on user input; and

wherein the variable pulse cycle alternates between the two or more different wavelengths of electromagnetic radiation.

24. The system of claim 1 , wherein the fluorescence source is tuned to emit a fluorescence excitation emission that excites a fluorescent reagent; and

wherein the image sensor detects the electromagnetic radiation and reads out a fluorescence exposure frame in response to the emitter pulsing the fluorescence excitation emission; and

wherein the fluorescence exposure frame comprises data for identifying a location of the fluorescent reagent within a scene.

25. The system of claim 1 , wherein at least a portion of the plurality of pulses of electromagnetic radiation emitted by the emitter is an excitation wavelength for fluorescing a reagent, and wherein the pixel array detects a relaxation wavelength of the reagent in response to the emitter pulsing the excitation wavelength.

26. The system of claim 1 , wherein the controller instructs the emitter to cycle the plurality of electromagnetic sources according to a variable pulse cycle, wherein the variable pulse cycle comprises:

a visible pulse comprising white light; and

a fluorescence pulse emitted by the fluorescence source, wherein the fluorescence pulse comprises electromagnetic radiation within the waveband from about 770 nm to about 795 nm;

wherein the pixel array detects the electromagnetic radiation and outputs a color exposure frame corresponding with the visible pulse and a fluorescence exposure frame corresponding with the fluorescence pulse; and

wherein the color exposure frame and the fluorescence exposure frames are processed to generate a Red-Green-Blue (RGB) image comprising an overlay highlighting a location of a target tissue structure within a scene.

27. The system of claim 1 , further comprising a filter that filters electromagnetic radiation having a wavelength from about 770 nm to about 795 nm.