Structures and methods are provided for obtaining depth information regarding a scene being imaged. The scene is illuminated with light having a time varying parameter. Light reflected from the scene is received and values for the time varying parameter associated with different portions of the scene are determined.
1. A filter, comprising:
a plurality of pixelated visible light filter elements, each of which transmits a band of visible light;
a plurality of pixelated invisible light filter elements, each of which transmits a band of invisible light; and,
a plurality of frequency counters, each respectively associated with a respective one of the invisible light filter elements and operable to measure the frequency of intensity modulations of the invisible light respectively transmitted therethrough.
2. The filter as recited in claim 1 , wherein the visible light is red, green, and blue light and the invisible light is infrared light.
3. The filter as recited in claim 1 , wherein the visible light is cyan, yellow, and magenta light and the invisible light is infrared light.
4. The filter as recited in claim 1 , wherein three visible light filter elements and one invisible light filter element define a pixel.
5. An imaging sensor, comprising:
an array of light sensitive elements;
a filter configured to transmit visible light to the array for two dimensional imaging and configured to transmit invisible light to the array for depth imaging; and,
an array of frequency counters, each respectively associated with a selected one of the invisible light sensitive elements and operable to measure the frequency of intensity modulations of the light respectively transmitted thereto.
6. The imager as recited in claim 5 , wherein the light sensitive elements comprise CMOS devices.
7. The imager as recited in claim 5 , wherein the filter comprises an IRGB filter.
8. A camera, comprising:
a source of invisible light associated with the camera that changes in frequency during imaging and is arranged to illuminate a scene being imaged by the camera;
an imaging sensor; and,
a filter configured to selectively transmit visible light to selected pixels of the imaging sensor and configured to transmit invisible light supplied directly thereto from the source combined with invisible light reflected back from the scene to other pixels of the imaging sensor a plurality of frequency counters, each respectively associated with a respective one of the invisible light filter elements and operable to measure the frequency of intensity modulations of the invisible light respectively transmitted there through.
9. The camera as recited in claim 8 , wherein the imaging sensor comprises a CMOS imaging sensor.
10. The camera as recited in claim 8 , wherein the filter comprises an IRGB filter.
11. The camera as recited in claim 8 , wherein the source of invisible light comprises a tunable infrared laser.
12. The camera as recited in claim 8 , further comprising a combiner configured to combine the infrared light reflected from the scene with the infrared light supplied directly thereto from the source and to provide the combined light to the imaging sensor.
13. The camera as recited in claim 8 , further comprising a frequency counter configured to count a beat frequency of the infrared light reflected from a scene after combination with the infrared light supplied directly thereto from the source.
14. The camera as recited in claim 8 , wherein the imaging sensor comprises at least one frequency counter configured to count a beat frequency from selected pixels thereof.
15. The camera as recited in claim 8 , wherein the imaging sensor comprises a dedicated frequency counter configured to count a beat frequency from infrared detecting pixels thereof.
16. A machine vision system, comprising:
a camera, comprising:
a source of invisible light associated with the camera that changes in frequency during imaging and arranged to illuminate an object being imaged by the camera;
an imager;
a filter configured to selectively transmit visible light to selected pixels of the imager and configured to transmit invisible light supplied directly thereto from the source combined with invisible light reflected back from the object to other pixels of the imager; and,
at least one device responsive to the imager a plurality of frequency counters, each respectively associated with a respective one of the invisible light filter elements and operable to measure the frequency of intensity modulations of the invisible light respectively transmitted there through.
17. A method of filtering light, the method comprising:
filtering a portion of a light beam through visible light filter elements of a filter;
filtering a portion of the same light beam through invisible light filter elements of the same filter; and,
counting a beat frequency of the light respectively filtered by the invisible light filter elements with respective frequency counters.