Videostroboscopy of vocal cords with CMOS sensors
The disclosure relates and extends to a light source having a strobing or pulsing sequence suitable for use with a CMOS sensor that does not require, have, or use a global shutter. Instead, the CMOS sensor synchronizes the strobing input with the blanking portion of the sensor readout pattern and disables the strobing during sensor readout, or when the strobing would otherwise leave artifacts in the image. The CMOS sensor freezes its readout during the strobing.
1. An endoscopic system comprising:
an endoscope for use in a videostroboscopy procedure;
a strobing light source configured to strobe a plurality of pulses of light in an environment at a desired frequency;
an imaging device comprising a CMOS sensor for imaging the environment by receiving one or more pulses of light of the plurality of pulses of light from the strobing light source as strobing input during a readout sequence comprising a pixel readout period and a blanking period;
a control unit for communicating with the CMOS sensor and the strobing light source;
wherein information obtained by the CMOS sensor is read out during the pixel readout period, and
wherein the pixel readout period is suspended at least once, creating a suspension period during the pixel readout period, and a pulse of light of the plurality of pulses of light from the strobing light source is pulsed during the suspension period.
2. The system of claim 1 , wherein at least one of the plurality of pulses of light from the strobing light source is suppressed during one or both of the pixel readout period-of the readout sequence and the blanking period of the readout sequence.
3. The system of claim 1 , wherein the light pulses that straddle the pixel readout period and the blanking period are suppressed.
4. The system of claim 1 , wherein the endoscope comprises a distal portion comprising a tip, wherein the CMOS sensor is located at the distal portion at the tip of the endoscope.
5. The system of claim 1 wherein the control unit is an imaging device control unit located remotely with respect to the CMOS sensor.
6. The system of claim 1 , wherein the strobing light source is independent from the CMOS sensor.
7. The system of claim 1 , wherein the strobing light source is pulsed during the blanking period of the readout sequence of the CMOS sensor.
8. The system of claim 1 , wherein the number of light pulses that occur during a single blanking period is the same as the number of light pulses that occur during the next, successive single blanking period.
9. The system of claim 1 , wherein the readout sequence is suspended a plurality of times, creating a plurality of suspension periods during the pixel readout period, and one pulse of light of the plurality of pulses of light from the strobing light source is pulsed during each suspension period of the plurality of suspension periods.
10. The system of claim 1 , wherein the system further comprises a microphone for continuously determining a frequency of a patient's vocal cords during the videostroboscopy procedure.
11. The system of claim 10 , wherein the desired frequency of the strobing light source is set to substantially match the patient's vocal cord frequency.
12. The system of claim 1 , wherein a plurality of images obtained during the readout sequence are superimposed to obtain a resultant image;
wherein each of the plurality of images corresponds to one of the plurality of pulses of light.
13. The system of claim 12 , wherein a digital gain is applied to a subset of rows in the resultant image in relation to a corresponding light pulse position.
14. The system of claim 1 , wherein a plurality of digital gains is applied to a plurality of subsets of rows in the resultant image in relation to corresponding light pulse positions.
15. The system of claim 1 , wherein a dedicated digital gain is applied to all rows in the resultant image in relation to corresponding light pulse positions.
16. The system of claim 12 , wherein a light deficiency for each row of the CMOS sensor is tracked in each superimposed image.
17. The system of claim 16 , wherein a digital gain is applied to normalize the resultant image into an artifact-free image.