Low-loss polarized light diversion

A method for using an endovascular catheter that provides lateral viewing while maintaining light polarization, the method comprising:

• inserting the endovascular catheter into a target of interest;
• conducting light from a light source through a waveguide within the sensor toward the distal end of the sensor,
• refracting light laterally from the sensor toward the target using a refractive optical element;
• refracting light scattered from the target using the refractive optical element within the sensor and conducing the light scattered from the sensor toward the proximal end of the sensor through the waveguide, wherein the refractive optical element is configured to lose less than about 40% of the polarization of refracted light polarization of the light is maintained during refraction by the refractive optical element.

A catheter that provides lateral viewing while maintaining light polarization, the catheter comprising:

• a catheter body configured to be inserted into a vessel within a human body;
• a light source is configured to provide cross-polarized light and is coupled with the catheter body;
• at least one fiber optic including a distal end and proximal end, wherein the proximal end of the fiber optic is coincident near the proximal end of the catheter body, the distal end of the fiber optic is coincident at a point near the distal end of the catheter body, the fiber optic is positioned within the catheter body, and the fiber optic receives light from the light source at the proximal end of the fiber optic and guides the light to the distal end of the fiber optic;
• and
• at least two prisms positioned within the catheter near the distal end of the fiber optic, wherein the at least two prisms are configured to refract light received from the distal end of the fiber optic outward from the catheter, wherein the at least two prisms are configured such that the polarization state of light loses less than about 40% of polarization of refracted light.