Open-field handheld fluorescence imaging systems and methods
An imaging device having an imaging field of view, the imaging device including at least one illumination port configured to output light for illuminating a target; an imaging sensor to detect light traveling along an optical path to the imaging sensor; and a first movable window positioned upstream of the sensor with respect to a direction of travel of light along the optical path, wherein the first movable window is configured to move into the optical path in a deployed position for modifying light received from the target.
1. A system for imaging a target, the system comprising:
one or more processors;
memory; and
one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for, within a period:
activating an excitation light source to generate an excitation pulse to illuminate the target;
receiving an ambient light intensity signal from a non-imaging sensor during a portion of the period in which the excitation light source is not activated;
exposing an image sensor for a fluorescent exposure time during the excitation pulse;
receiving outputs from the image sensor;
compensating for ambient light based on the ambient light intensity signal; and
storing a resultant image in the memory,
wherein the one or more programs include instructions for determining a periodic frequency of the ambient light intensity,
wherein compensating for ambient light comprises:
synthesizing or extracting, from one or more received ambient light intensity signals, a complete periodic cycle of ambient light intensity having the determined periodic frequency,
extending the ambient light intensity periodic cycle to a time period corresponding to the fluorescence exposure time,
calculating a first accumulated ambient light value corresponding to an area under the curve of ambient light intensity during a background exposure time,
calculating a second accumulated ambient light value corresponding to an area under the curve of the ambient light intensity during the fluorescence exposure time,
scaling the received image sensor output for the background exposure time and the received image sensor output for the fluorescence exposure time based on a ratio of the first and second accumulated ambient light values, and
subtracting the scaled image sensor output for the background exposure time from the scaled image sensor output for the fluorescence exposure time to form the resultant image.
2. The system of claim 1 , wherein the one or more programs include instructions for, within the period:
activating a white light source to generate a white light pulse to illuminate the target such that the white light pulse does not overlap the excitation pulse; and
exposing the image sensor for a visible exposure time during at least one white light pulse.
3. The system of claim 1 , wherein the one or more programs include instructions for exposing the image sensor for a background exposure time when the target is not illuminated.
4. The system of claim 1 , wherein the one or more programs include instructions for receiving an ambient light intensity signal from the non-imaging sensor during the background exposure time.
5. The system of claim 1 , wherein the one or more programs include instructions for extending the ambient light intensity periodic cycle to the time period corresponding to the fluorescence exposure time.
6. A method for imaging a target, the method comprising:
at a system having one or more processors and memory:
activating an excitation light source to generate an excitation pulse to illuminate the target;
receiving an ambient light intensity signal from a non-imaging sensor during a portion of the period in which the excitation light source is not activated;
exposing an image sensor for a fluorescent exposure time during the excitation pulse;
receiving outputs from the image sensor;
determining a periodic frequency of the ambient light intensity;
compensating for ambient light based on the ambient light intensity signal, wherein compensating for ambient light comprises:
synthesizing or extracting, from one or more received ambient light intensity signals, a complete periodic cycle of ambient light intensity having the determined periodic frequency,
extending the ambient light intensity periodic cycle to a time period corresponding to the fluorescence exposure time,
calculating a first accumulated ambient light value corresponding to an area under the curve of ambient light intensity during a background exposure time,
calculating a second accumulated ambient light value corresponding to an area under the curve of the ambient light intensity during the fluorescence exposure time,
scaling the received image sensor output for the background exposure time and the received image sensor output for the fluorescence exposure time based on a ratio of the first and second accumulated ambient light values, and
subtracting the scaled image sensor output for the background exposure time from the scaled image sensor output for the fluorescence exposure time to form the resultant image; and
storing a resultant image in the memory.
7. The method of claim 6 , further comprising, within the period:
activating a white light source to generate a white light pulse to illuminate the target such that the white light pulse does not overlap the excitation pulse; and
exposing the image sensor for a visible exposure time during at least one white light pulse.
8. The method of claim 6 , further comprising exposing the image sensor for a background exposure time when the target is not illuminated.
9. The method of claim 6 , further comprising receiving an ambient light intensity signal from the non-imaging sensor during the background exposure time.
10. The method of claim 6 , further comprising extending the ambient light intensity periodic cycle to the time period corresponding to the fluorescence exposure time.
11. The method of claim 6 , wherein the non-imaging sensor is configured to detect a periodic frequency of the ambient light intensity that results from a frequency of an ambient light power source.
12. The system of claim 1 , wherein the non-imaging sensor is configured to detect a periodic frequency of the ambient light intensity that results from a frequency of an ambient light power source.