Method and apparatus for concurrent imaging at visible and infrared wavelengths

1. A method of operating an imaging system, the method comprising:

applying a fluorescent dye to a target tissue;

providing a near infrared (NIR) excitation light source operable to produce NIR excitation light having an excitation wavelength;

providing a surgical lamp operable to produce continuous visible illumination light having visible wavelengths;

concurrently illuminating the target tissue with the NIR excitation light produced by the NIR excitation light source and the continuous visible illumination light produced using the surgical lamp;

collecting fluorescent emission from the target tissue;

collecting visible light reflected from the target tissue;

passing the collected fluorescent emission and the reflected visible light through the imaging system, wherein the imaging system comprises:

a single image sensor;

a first filter operable to reduce an intensity of light at the excitation wavelength; and

a visible light attenuator disposed between the target tissue and the single image sensor and operable to reduce an intensity of the reflected visible light;

forming an image of the target tissue using the single image sensor by concurrently detecting the fluorescent emission and attenuated reflected visible light; and

adjusting the NIR excitation light source to modify a contrast of the image of the target tissue.

2. The method of claim 1 wherein the first filter is operable to block substantially all light at the excitation wavelength.

3. The method of claim 1 wherein the first filter and the visible light attenuator are integrated as a single dichroic filter.

4. The method of claim 1 wherein the NIR excitation light source comprises a diode laser or light emitting diode.

5. The method of claim 1 wherein the NIR excitation light, the fluorescent emission, and the reflected visible light propagate along a coaxial propagation path.

6. The method of claim 1 wherein the single image sensor comprises a single chip CCD or CMOS sensor.

7. A fluorescent imaging system for concurrently imaging at both NIR and visible wavelengths, the fluorescent imaging system comprising:

a camera head;

a surgical lamp operable to provide continuous visible illumination light to illuminate a tissue;

a controller coupled to the camera head; and

an image display device,

wherein the camera head comprises:

an NIR light source operable to generate NIR excitation light to illuminate the tissue, wherein NIR fluorescent light is emitted from the tissue;

a first filter operable to reduce an intensity of the NIR excitation light;

a visible light attenuator operable to reduce an intensity of reflected visible light; and

a single image sensor operable to detect an intensity of the NIR fluorescent light and the intensity of the reflected visible light concurrently, wherein the visible light attenuator is disposed between the tissue and the single image sensor.

8. The fluorescent imaging system of claim 7 wherein the NIR light source comprises at least one solid state light source and the single image sensor comprises a single chip CCD or CMOS sensor.

9. The fluorescent imaging system of claim 7 wherein the controller is operable to vary an intensity of the NIR excitation light.

10. The fluorescent imaging system of claim 7 wherein:

the NIR excitation light propagates along an illumination path;

the NIR fluorescent light propagates along an imaging path; and

the reflected visible light propagates along the imaging path, wherein the illumination path and the imaging path are coaxial.

11. The fluorescent imaging system of claim 7 wherein:

the NIR excitation light propagates along an illumination path;

the NIR fluorescent light propagates along an imaging path; and

the reflected visible light propagates along the imaging path, wherein the illumination path and the imaging path are oriented at an angle to each other.

12. A method of operating a fluorescent imaging system during an open surgery procedure, the method comprising:

concurrently illuminating a tissue with near infrared (NIR) excitation light provided by a NIR light source and continuous visible light provided by a surgical lamp, wherein NIR fluorescent light is emitted from the tissue;

collecting the NIR fluorescent light and reflected visible light that is reflected from the tissue;

blocking at least a portion of the NIR excitation light reflected from the tissue by a first filter;

attenuating the reflected visible light by a visible light attenuator disposed between the tissue and a single image sensor; and

concurrently imaging, using the single image sensor, the NIR fluorescent light and the attenuated reflected visible light.

13. The method of claim 12 wherein the at least a portion of the NIR excitation light is substantially all of the NIR excitation light.

14. The method of claim 12 further comprising adjusting an intensity of the NIR excitation light to modify a contrast between the NIR fluorescent light and the attenuated reflected visible light.

15. The method of claim 14 wherein adjusting the intensity of the NIR excitation light is performed by a controller coupled to the single image sensor.

16. The method of claim 12 wherein at least a portion of the tissue is exposed to a fluorescent dye.

17. The method of claim 12 wherein the NIR light source is a component of the fluorescent imaging system.

18. The method of claim 12 wherein the single image sensor comprises a single chip CCD or CMOS sensor.