Method and apparatus for illuminating an object field imaged by an image sensor

Inventors

Chinnock, Randal B. • Weber, William L.

Assignees

Conavi Medical Inc • Ximedica LLC

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 describes an illuminator apparatus and method for illuminating an object field using an integrating element that produces a generally homogenous illumination beam at a rectangular output face. At least one input light source is coupled to an input end of the integrating element, and an illumination projector projects an image of the output face of the integrating element onto the object field to produce an illuminated region. An imaging apparatus including an image sensor is configured to image a portion of the object field corresponding to the illuminated region.

The system is configured so that images captured by the image sensor are captured through a polarizer having a polarization direction operable to reduce specular reflections from objects within the object field. The described framework further supports refinements in which the illuminated region is sized relative to the image sensor and may be overfilled, and wherein illumination and capture are coordinated across different light sources. In particular, the approach includes sequential activation of multiple input light sources, synchronization of the image sensor to capture separate image frames, and combining the frames into a single combined image.

Additional refinements specify multi-light-source illumination with differing spectral properties, including selected options that include red, green, blue, and tunable light sources. The image sensor may be structured with multiple sensor elements that are responsive to light having spectral properties spanning those of corresponding input light beams, with the separate image frames captured using all sensor elements. A desired spectral illumination characteristic may be selected to enhance features in the object field.

Claims Coverage

The independent claims cover two aspects: (i) an imaging system that projects an integrating element output face image onto an object field, images the illuminated region, and captures images through a polarizer to reduce specular reflections; and (ii) a corresponding method for illuminating an object field using an integrating element projection onto the object field, with imaging through a polarizer to reduce specular reflections. Across these independent claims and their dependents, the claims incorporate multiple inventive features related to integrating-element homogeneity, projection of the output face, sensor-region correspondence, specular reflection reduction via polarizer use, and optional geometry matching and multi-spectral/sequential acquisition.

Overall, the claim coverage centers on producing a generally homogeneous illumination beam with an integrating element, projecting an image of the integrating element output face to define an illuminated region on the object field, imaging a corresponding portion of the object field with an image sensor, and capturing images through a polarizer operable to reduce specular reflections. Dependent claim coverage further adds region/sensor geometry constraints and optional sequential multi-light-source operation with synchronized frame capture and combining, including sensor spectral-responsivity matching and selection of a desired spectral illumination characteristic to enhance features.

Stated Advantages

Documented Applications