Needle with Optical Fiber for Raman Signal Measurement

An apparatus comprising:

• a needle comprising a substantially cylindrical shaft and a lumen, wherein the lumen comprises a hollow space located within the shaft, and the shaft comprises a tip located at an end of the shaft;
• an optical fiber comprising an end face, wherein the end face and at least a portion of the optical fiber are located within the lumen, and the optical fiber is configured to transmit a pump-Stokes beam of light along the optical fiber toward the tip of the needle and to the end face, wherein the pump-Stokes beam is emitted from the end face and directed to a sample located in the lumen, wherein the pump-Stokes beam is configured to produce a Raman signal by coherent Raman scattering of the pump-Stokes beam while propagating through the sample;
• and
• a mirror configured to reflect at least the Raman signal to direct the Raman signal to the end face of the optical fiber, wherein:
• the optical fiber is further configured to receive at least a portion of the Raman signal via the end face and transmit the received Raman signal along the optical fiber in a direction opposite the pump-Stokes beam.