Method and system for multiple f-number lens

A method of operating an imaging system the method comprising:

• emitting, using a near infrared (NIR) light source of the imaging system, a plurality of NIR light pulses toward one or more first objects, wherein a portion of each of the plurality of NIR light pulses is reflected off of the one or more first objects;
• receiving and transmitting, using a first set of lens elements of the imaging system, the portion of each of the plurality of NIR light pulses reflected off of the one or more first objects and visible light from an ambient light source reflected or scattered off of one or more second objects;
• receiving, using a wavelength-selective filter positioned at an aperature stop of the imaging system, the portion of each of the plurality of NIR light pulses reflected off of the one or more first objects and the visible light from an ambient light source reflected or scattered off of one or more second objects transmitted by the first set of lens elements, wherein the wavelength-selective filter includes:
• a central region with a first linear dimension, the central region configured to transmit both the portion of each of the plurality of NIR light pulses reflected off of the one or more first objects and the visible light from an ambient light source reflected or scattered off of one or more second objects transmitted by the first set of lens elements;
• and
• an outer region surrounding the central region with a second linear dimension greater than the first linear dimension, the outer region configured to transmit only the the portion of each of the plurality of NIR light pulses reflected off of the one or more first objects transmitted through the first set of lens elements;
• directing, using a dichroic beam splitter of the imaging system, the portion of each of the plurality of NIR light pulses transmitted through the wavelength-selective filter along a first optical path;
• receiving and transmitting, using a second set of lens elements of the imaging system positioned along the first optical path, the portion of each of the plurality of NIR light pulses, wherein the first set of lens elements, the aperature stop, the wavelength-selective filter, and the second set of lens elements form a first lens system, the first lens system defining a first focal plane;
• detecting, using a first image sensor of the imaging system that is disposed along the first optical path at the first focal plane of the first lens system, the portion of each of the plurality of NIR light pulses;
• forming a three-dimensional image of the one or more first objects by determining a time of flight for the portion of each of the plurality of NIR light pulses from emission to detection;
• directing, using the dichroic beam splitter, the visible light transmitted through the wavelength-selective filter along a second optical path;
• and
• detecting, using a second image sensor of the imaging system that is disposed along the second optical path, a two-dimensional intensity image of the one or more second objects.