Surgical lighting system co-illumination detection

1. A method for operating a lighting system having a first lighthead and a second lighthead distinct from the first lighthead, the second lighthead having associated therewith a light sensor configured to detect an intensity of visible light incident on the target surface in the region where the second lighthead is focused, the method comprising:

varying a characteristic of visible light emitted by the first lighthead according to a predefined profile;

fixing a characteristic of visible light emitted by the second lighthead;

detecting by the light sensor a characteristic of visible light incident on the target surface over a period of time;

comparing the characteristic of the light detected by the light sensor over the period of time to the characteristic of light defined in the predetermined profile; and

determining if the first and second lighthead are operating in a co-illumination state or an independent state based on the comparison.

2. The method according to claim 1 , further comprising setting a mode of operation of the first and second lighthead based on the determined operating state.

3. The method according to claim 1 , wherein setting comprises setting the mode of operation of the first and second lighthead to co-illumination mode when the comparison indicates the characteristic of the light detected by the light sensor is sufficiently well correlated with the characteristic of light defined by the predetermined profile.

4. The method according to claim 1 , wherein setting comprises setting the mode of operation of the first and second lighthead to independent mode when the comparison indicates the characteristic of the light detected by the light sensor is substantially non-varying.

5. The method according to claim 1 , further comprising upon setting co-illumination mode of operation, ramping an intensity of light emitted by the first and second lightheads down such that a combined light intensity produced by the first and second lightheads is at a predetermined intensity.

6. The method according to claim 1 , wherein the predetermined profile comprises a characteristic of light that has a sinusoidal profile.

7. The method according to claim 1 , wherein the predetermined profile has a characteristic of light that varies in frequency.

8. The method according to claim 6 , wherein the predetermined profile has a frequency less than 1 Hertz.

9. The method according to claim 1 , wherein the characteristic comprises an intensity of light.

10. The method according to claim 9 , wherein the characteristic is an intensity of light, and varying includes varying a peak-to-peak intensity of light by about 30 percent relative to a nominal intensity.

11. A surgical lighting system, comprising:

a first lighthead configured to selectively emit a first visible light in a first direction;

a second lighthead distinct from the first lighthead, the second lighthead configured to selectively emit a second visible light in a second direction;

a sensor corresponding to the second lighthead and configured to sense visible light in a focal area of the second lighthead; and

a controller operatively coupled to the first lighthead, the second lighthead, and the sensor, the controller configured to

vary a characteristic of the first visible light over a period of time according to a predefined profile,

fix a characteristic of the second visible light over the period of time, and

compare a characteristic of the light detected by the light sensor over the predetermined time to a characteristic of light in the predetermined profile; and

determine if the first and second lighthead are operating in a co-illumination state or an independent state based on the comparison.

12. The surgical light according to claim 11 , wherein the controller is configured to set a mode of operation of the first and second lighthead based on the determined operating state.

13. The surgical light according to claim 10 , wherein the controller is configured to set the mode of operation of the first and second lighthead to co-illumination mode when the comparison indicates the characteristic of the light detected by the light sensor is sufficiently well correlated with the characteristic of light in the predetermined profile.

14. The surgical light according to claim 11 , wherein the controller is configured to set the mode of operation of the first and second lighthead to independent mode when the comparison indicates the characteristic of the light detected by the light sensor is substantially non-varying.

15. The surgical light according to claim 11 , wherein the controller, upon setting co-illumination mode, is configured to ramp an intensity of light emitted by the first and second lightheads down such that a combined light intensity produced by the first and second lightheads is at a predetermined intensity.

16. The surgical light according to claim 11 , wherein the predetermined profile is a sinusoidal profile.

17. The surgical light according to claim 11 , wherein the predetermined profile varies a frequency of a characteristic of the emitted light.

18. The surgical light according to claim 16 , wherein a frequency of the predetermined profile is less than 1 Hertz.

19. The surgical light according to claim 11 , wherein a peak-to-peak intensity of light set by the predetermined profile varies by up to about 30 percent relative to a nominal intensity.