Rolling-reset imager

1. A method for capturing an image of a moving object comprising:

setting a minimum frame rate for a rolling-reset imager based on at least a velocity of the moving target, the rolling-reset imager including sensor pixels;

wherein the moving object includes multiple elements, and wherein there is a minimum width in the direction the object moves defined by at least one of the elements;

operating the rolling-reset imager on a rolling-reset basis to create frames having substantially all the sensor pixels in an exposed state, the frames created at a frame rate of at least the minimum frame rate;

pulsing an illumination source during each frame to produce pulsed illumination, where the pulsed illumination has a duration, the duration defines an exposure time for capturing the image of the moving object, and the illumination duration is based on the minimum element width in the direction the object moves and the velocity of the object;

reflecting ambient illumination and the pulsed illumination off the moving object; and

forming a pixelized electronic representation of the moving object on a rolling-reset basis substantially during the exposure time and substantially using the pulsed illumination reflected off the moving object.

2. A method for capturing an image of a moving object according to claim 1 , the pulsed illumination having a predominant frequency range, further comprising:

filtering the illumination reflected off the moving object to attenuate radiation outside the predominant frequency range by a greater attenuation factor than radiation within the predominant frequency range;

wherein forming the pixelized electronic representation of the moving object on a rolling-reset basis substantially uses the filtered illumination.

3. A method for capturing an image of a moving object according to claim 2 wherein the predominant frequency range includes near infrared.

4. A method for capturing an image of a moving object according to claim 3 wherein the predominant frequency range is about 700 nm to about 950 nm.

5. A method for capturing an image of a moving object according to claim 2 wherein the predominant frequency range includes visible light.

6. A method for capturing an image of a moving object according to claim 5 wherein the predominant frequency range is about 400 nm to about 700 nm.

7. A method for capturing an image of a moving object according to claim 1 , wherein the illumination duration is based on the result of dividing the minimum element width in the direction the object moves by the velocity of the object.

8. A method for capturing an image of a moving object comprising:

setting a minimum frame rate for a rolling-reset imager based on at least a velocity of the moving target, the rolling-reset imager including sensor pixels;

operating the rolling-reset imager on a rolling-reset basis to create frames having substantially all the sensor pixels in an exposed state, the frames created at a frame rate of at least the minimum frame rate;

pulsing an illumination source during each frame to produce pulsed illumination, where the pulsed illumination has a duration and the duration defines an exposure time for capturing the image of the moving object;

reflecting ambient illumination and the pulsed illumination off the moving object; and

forming a pixelized electronic representation of the moving object on a rolling-reset basis substantially during the exposure time and substantially using the pulsed illumination reflected off the moving object; and

wherein the rolling-reset imager has a field of view with a width extending in the direction the object moves, the object has a width in the direction the object moves, and the minimum frame rate is based on the velocity at which the object moves, the width of the field of view in the direction the object moves, and the width of the object in the direction the object moves.

9. A method for capturing an image of a moving object according to claim 8 , wherein the minimum frame rate is based on V/(W F −W O ), where V is the velocity at which the object moves, W F is the width of the field of view in the direction the object moves, and W O is the width of the object in the direction the object moves.

10. An imaging system comprising:

a rolling-reset imager having a field of view, the field of view including a width extending in a direction that a moving object moves, the rolling-reset imager forming an image of the moving object on a rolling-reset basis when the object moves through the width of the field of view extending in the direction the object moves, the rolling-reset imager including image sensor pixels, the rolling-reset imager having a minimum frame rate based on at least a velocity at which the object moves;

wherein the moving object includes multiple elements, where there is a minimum width in the direction the object moves defined by at least one of the elements;

a light source illuminating the object with pulsed light having an illumination frequency spectrum and an illumination pulse width, the pulse width defining an effective exposure time for forming the image of the object; and

the illumination pulse width is based on the result of dividing the minimum element width in the direction the object moves by the velocity of the object.

11. An imaging system as set forth in claim 10 , wherein the illumination frequency spectrum contains predominantly visible frequencies.

12. An imaging system as set forth in claim 11 , wherein the illumination frequency spectrum wavelengths in a range of about 400 nm to about 700 nm.

13. An imaging system as set forth in claim 12 , further comprising an optical filter disposed between the object and the rolling-reset imager, the optical filter having a frequency pass band permitting transmission of a significant portion of the illumination frequency spectrum while at least partially inhibiting transmission of at least some light having frequencies outside the illumination frequency spectrum.

14. An imaging system as set forth in claim 11 , further comprising an optical filter disposed between the object and the rolling-reset imager, the optical filter having a frequency pass band permitting transmission of a significant portion of the illumination frequency spectrum while at least partially inhibiting transmission of at least some light having frequencies outside the illumination frequency spectrum.

15. An imaging system comprising:

a rolling-reset imager having a field of view, the field of view including a width extending in a direction that a moving object moves, the rolling-reset imager forming an image of the moving object on a rolling-reset basis when the object moves through the width of the field of view extending in the direction the object moves, the rolling-reset imager including image sensor pixels, the rolling-reset imager having a minimum frame rate based on at least a velocity at which the object moves; and

a light source illuminating the object with pulsed light having an illumination frequency spectrum and an illumination pulse width, the pulse width defining an effective exposure time for forming the image of the object; and

wherein the minimum frame rate is further based on the width of the field of view in the direction the object moves, and the width of the object in the direction the object moves.

16. An imaging system as set forth in claim 15 , wherein the minimum frame rate is based on V/(W F −W O ), where V is the velocity at which the object moves, W F is the width of the field of view in the direction the object moves, and W O is the width of the object in the direction the object moves.