Method and apparatus for illuminating an object field imaged by an image sensor
Inventors
Chinnock, Randal B. • Weber, William L.
Assignees
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Publication Number
US-11051686-B2
Publication Date
2021-07-06
Expiration Date
Abstract
An illuminator apparatus and method for illuminating an object field imaged by a rectangular image sensor having a first aspect ratio is disclosed. The apparatus includes an optical fiber having a proximal end disposed to receive a plurality of input light beams, each light beam having differing spectral properties, the optical fiber being operable to transmit the light beams along the fiber to a distal end of the optical fiber. The apparatus also includes an integrating element disposed to receive the light beams from the distal end of the fiber and combine the light beams to produce a generally homogenous illumination beam at a rectangular output face of the integrating element. The apparatus further includes an illumination projector operable to project an image of the output face of the integrating element into the object field to produce a generally rectangular illuminated region of the object field substantially corresponding to the portion of the object field imaged by the rectangular image sensor.
Core Innovation
The invention provides an imaging system that includes at least one input light source and an integrating element having an input end and an output face. The integrating element receives the input light source at the input end and produces a generally homogenous illumination beam at the output face. An illumination projector projects an image of the output face of the integrating element onto an object field to produce an illuminated region of the object field.
The invention further uses polarizers in the illumination and imaging paths to reduce specular reflections. The illumination projector includes a first polarizer configured to cause the illuminated region to be illuminated by polarized light having a first polarization direction. Images captured by the image sensor are captured through a second polarizer having a second polarization direction that is operable to reduce specular reflections from objects within the object field.
In the related claim set, multiple light sources are used and may be sequentially activated, with an image sensor capturing separate image frames and combining the captured frames to produce a combined image of the object field. The integrating-element projection defines the illuminated region that corresponds to a portion of the object field imaged by the image sensor, and the claims also specify geometric correspondence using aspect ratios and may size the illuminated region to cause the image sensor to be at least partially overfilled in at least one direction.
Claims Coverage
The document includes three independent claims: an imaging system claim, a method claim, and an imaging system claim with sequential activation of multiple light sources. Across these independent claims, the coverage centers on an integrating element with a projected output-face image to define an illuminated region, image capture through a second polarizer to reduce specular reflections, and controller-driven sequential illumination with synchronized multi-frame capture and frame combination.
Homogenous illumination beam from integrating element output face
An integrating element configured to receive at least one input light source at the input end and to produce a generally homogenous illumination beam at the output face.
Projected image of integrating element output face to define illuminated region
An illumination projector being configured to project an image of the output face of the integrating element onto an object field to produce an illuminated region of the object field.
Polarized illumination via first polarizer with first polarization direction
The illumination projector comprising a first polarizer configured to cause the illuminated region to be illuminated by polarized light having a first polarization direction.
Image capture through second polarizer to reduce specular reflections
Images captured by the image sensor are captured through a second polarizer having a second polarization direction operable to reduce specular reflections from objects within the object field.
Sequential activation, synchronized capture, and frame combination for combined image
A controller being configured to sequentially activate each of the plurality of light sources to cause the object field to be sequentially illuminated by each of the respective input light beam; synchronize the image sensor to capture separate image frames while the object field is being illuminated by each of the respective input light beam; and combine the captured separate image frames to produce a combined image of the object field.
Overall, claim coverage focuses on generating generally homogenous illumination with an integrating element, projecting an image of the integrating element output face to create an illuminated region on an object field, and using a first polarizer for illumination polarization and a second polarizer in image capture to reduce specular reflections. A further independent claim adds controller-driven sequential activation of multiple light sources with synchronized separate-frame capture and combination into a combined image.
Stated Advantages
Improved efficiency.
Reduced heat/glare.
Reduced sensitivity spectral components.
Reduced specular reflections from objects within the object field.
Documented Applications
Applicability to enclosed-space imaging such as laparoscopic surgery.
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