Imaging system for combined full-color reflectance and near-infrared imaging
View Patent ↗An imaging system for acquisition of NIR and full-color images includes a light source providing visible light and NIR light to an area under observation, such as living tissue, a camera having one or more image sensors configured to separately detect blue reflectance light, green reflectance light, and combined red reflectance light/detected NIR light returned from the area under observation. A controller in signal communication with the light source and the camera is configured to control the light source to continuously illuminate area under observation with temporally continuous blue/green illumination light and with red illumination light and NIR excitation light. At least one of the red illumination light and NIR excitation light are switched on and off periodically in synchronism with the acquisition of red and NIR light images in the camera.
1. A method for acquisition of NIR and full-color images, comprising the steps of:
illuminating a sample area with blue light and green light continuously, and, at the same time, illuminating the sample area with red light and NIR light according to a predetermined timing scheme in which at least one of the red light and the NIR light is switched on and off periodically;
directing blue reflectance light to a blue light detector, directing green reflectance light to a green light detector, and directing red reflectance light and NIR fluorescence light to a red/NIR light detector, wherein the red reflectance light and/or NIR fluorescence is detected by the red/NIR light detector in synchronism with the predetermined timing scheme;
simultaneously acquiring first image signals from the blue light detector, second image signals from the green light detector, and third image signals from the red/NIR light detector, the third image signals being multiplexed red light and NIR fluorescence image signals;
determining from the third image signals and the predetermined timing scheme red reflectance light image signals and NIR fluorescence image signals separate from one another;
generating a full-color image of the sample area from the first image signals and the second image signals and the separately determined red reflectance light signals;
generating an NIR image from the separately determined NIR fluorescence image signals; and
simultaneously displaying the full-color image and the NIR image.
2. The method of claim 1 , wherein the sample area is alternatingly illuminated with red light and NIR light.
3. The method of claim 2 , wherein a time duration of red light illumination is different from a time duration of NIR light illumination.
4. The method of claim 3 , wherein the time duration of red light illumination is longer than the time duration of NIR light illumination.
5. The method of claim 2 , wherein a time duration of red light illumination is substantially identical to a time duration of NIR light illumination.
6. The method of claim 1 , wherein the sample area is continuously illuminated with red light and periodically illuminated with NIR light.
7. The method of claim 1 , wherein the sample area is continuously illuminated with NIR light and periodically illuminated with red light.
8. The method of claim 1 , wherein the red light or NIR light, or both, are switched at video rates.
9. The method of claim 2 , wherein image fields lacking the red reflectance light spectral component or the detected NIR light spectral component are interpolated from temporally adjacent image fields that include a corresponding red reflectance light spectral component or detected NIR light spectral component.
10. The method of claim 7 , wherein the NIR light spectral component obtained in the absence of red light illumination is subtracted from the combined red reflectance light/detected NIR light to obtain the separate red reflectance light spectral component.
11. The method of claim 1 , wherein spatial information of the sample area is primarily derived from the blue reflectance light and the green reflectance light.
12. The method of claim 1 , wherein the detected NIR light is fluorescence light.
13. The method of claim 1 , wherein the step of simultaneously displaying further includes displaying the full-color image and the NIR image in real time.
14. An imaging system for acquisition of NIR images and full-color images comprising:
a light source providing visible light and NIR light to a sample area;
a camera having a blue light detector configured to detect blue reflectance light, a green light detector configured to detect green reflectance light, and a red/NIR light detector configured to detect red reflectance light and NIR fluorescence returned from the sample area:
a controller in signal communication with the light source and the camera for:
illuminating the sample area with blue light and green light continuously and, at the same time, illuminating the sample area with red light and NIR light according to a predetermined timing scheme in which at least one of the red light and the NIR light is switched on and off periodically,
simultaneously acquiring first image signals from the blue light detector, second image signals from the green light detector, and third image signals from the red/NIR light detector,
determining from the third image signals and the predetermined timing scheme the red reflectance light image signals and NIR fluorescence image signals separately from one another, wherein red reflectance light image signals and the NIR fluorescence image signals are determined in synchronism with the switched red light and NIR light; and
a display receiving the first image signals, the second image signals, and the separately determined red reflectance light image signals of the third image signals and rendering therefrom a full-color reflectance image of the sample area, the display further receiving the separately determined NIR fluorescence image signals of the third image signals and rendering therefrom an NIR image of the sample area.
15. The imaging system of claim 14 , wherein the sample area is alternatingly illuminated by the light source with red light and NIR light.
16. The imaging system of claim 14 , wherein the light source comprises
an illuminator emitting a substantially constant intensity of visible light and NIR light over a continuous spectral range, and
a plurality of filters disposed between the illuminator and the sample area for transmitting temporally continuous blue/green light and temporally discontinuous red light and discontinuous NIR light.
17. The imaging system of claim 14 , wherein the light source comprises
an illuminator emitting a substantially constant intensity of visible light and NIR light over a continuous spectral range,
first dichroic means for separating the visible light and NIR light into blue/green and red light and NIR light,
shutter means for transforming the separated red light and NIR light into temporally discontinuous red light and discontinuous NIR light, and
second dichroic means for combining the blue/green light, the temporally discontinuous red light and the temporally discontinuous NIR light for transmission to the sample area.
18. The imaging system of claim 14 , wherein the light source comprises
a first illuminator emitting a substantially constant intensity of green and blue light,
a second illuminator producing switched red light,
a third illuminator producing switched NIR light, and
dichroic means for combining the switched red light and the switched NIR light with the green and blue light for transmission to the sample area.
19. The imaging system of claim 18 , wherein the switched red light and the NIR light are produced by interrupting a continuous intensity light beam of the red light and the NIR light by a shutter or chopper.
20. The imaging system of claim 18 , wherein the switched red light and the NIR light are produced by electrically switching the second illuminator and the third illuminator on and off.
21. The imaging system of claim 14 , wherein the image sensors employ an interlaced scan.
22. The imaging system of claim 14 , wherein the image sensors employ a progressive scan.
23. The imaging system of claim 14 , further comprising a dichroic prism assembly spectrally separating the blue reflectance light, the green reflectance light and the combined red reflectance light/detected NIR light returned from the sample area and directing the separated light to different exit faces of the dichroic prism assembly, wherein the one or more image sensors comprise three image sensors, each mounted on a different exit face.
24. The imaging system of claim 14 , wherein the one or more image sensors comprise a single image sensor having pixels, each pixel responsive to one of the blue reflectance light, the green reflectance light and the combined red reflectance light/detected NIR light returned from the sample area.
25. The imaging system of claim 24 , wherein the single image sensor comprises a mosaic blue/green/red-NIR filter array disposed before the sensor pixels.
26. The imaging system of claim 14 , wherein the one or more image sensors comprise a single image sensor having a plurality of stacked layers, each layer having pixels responsive to one of the blue reflectance light, the green reflectance light and the combined red reflectance light/detected NIR light returned from the sample area.
27. The imaging system of claim 14 , wherein the imaging system is configured as an endoscope.
28. The imaging system of claim 14 , wherein the detected NIR light is fluorescence light.
29. The imaging system of claim 14 , wherein the display is configured to render the full-color reflectance image of the sample area and the NIR image of the sample area in real time.