Method and apparatus for illuminating an object field imaged by a rectangular 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 is an illuminator apparatus for imaging an object field using a rectangular image sensor, where at least one input light beam is transmitted along an optical fiber to a distal end. The distal end couples the at least one input light beam into an integrating element that produces a generally homogenous illumination beam at a rectangular output face. An illumination projector projects an image of the rectangular output face onto the object field to produce a generally rectangular illuminated region.

The invention matches the rectangular illumination geometry to a portion of the object field imaged by the rectangular image sensor. A rectangular image sensor having a first aspect ratio images the portion of the object field, and the rectangular illuminated region of the object field substantially corresponds to the portion of the object field imaged by the rectangular image sensor. In refinements, the generally rectangular illuminated region has a second aspect ratio that is substantially equivalent to the first aspect ratio.

Further refinements extend the illumination and imaging to reduce artifacts and enable spectral effects. The projected image can be projected through a first polarizer so the object field is illuminated by polarized light having a first polarization direction, while images captured by a rectangular image sensor are captured through a second polarizer having a second polarization direction operable to reduce specular reflections. The document also describes using multiple input light beams produced by activating multiple light sources and, in some embodiments, sequentially activating the multiple light sources, synchronizing image sensor frame capture for each illumination, and combining frames.

The document also describes selecting a desired spectral illumination characteristic using a rectangular image sensor with reduced sensitivity to certain spectral components and increasing the associated power level of those spectral components.

Claims Coverage

The patent includes three independent claims: one system claim and two method claims. Across these claims, the core inventive features are the fiber-delivered integrating element producing a homogenous rectangular output face, projection to form a generally rectangular illuminated region that substantially corresponds to a rectangular sensor-imaged portion, and optional refinements addressing polarization-based specular reflection reduction, sequential multi-source illumination with synchronized frame capture and frame combination, and spectral-power selection tied to reduced sensor sensitivity.

Overall, the independent claims cover a system and methods that deliver at least one input light beam through an optical fiber to a distal integrating element to generate a homogenous rectangular output face, project the rectangular output face to form a generally rectangular illuminated region, and image a substantially corresponding portion of the object field with a rectangular image sensor having a specified aspect ratio. Additional claim coverage includes projecting and imaging through polarizers to reduce specular reflections, and refinements including sequential activation with synchronized separate frame capture and frame combination, and spectral-power selection based on reduced sensor sensitivity.

Stated Advantages

Documented Applications