Needle with Optical Waveguide for Raman Signal Measurement

A method comprising:

• producing, by a Raman spectroscopy system, a pump-Stokes beam of light, wherein the pump-Stokes beam of light comprises a pump beam of light at a pump frequency and a Stokes beam of light at a Stokes frequency, wherein the pump and Stokes frequencies are offset by a frequency offset Ω;
• sending, by the Raman spectroscopy system, the pump-Stokes beam of light to a needle-waveguide apparatus coupled to the Raman spectroscopy system, wherein the needle-waveguide apparatus comprises:
• a needle comprising a substantially cylindrical shaft comprising a tip located at a distal end of the shaft, the tip comprising an opening;
• and
• an optical waveguide located within the shaft of the needle, wherein the optical waveguide is configured to (i) receive the pump-Stokes beam of light produced by the Raman spectroscopy system, wherein the pump-Stokes beam of light is received from an optical fiber having an end face located at a proximal end of the shaft opposite the distal end and (ii) convey the pump-Stokes beam along the optical waveguide to the tip of the needle and through the opening of the needle;
• receiving, by the Raman spectroscopy system, a Raman signal produced by coherent Raman scattering of the pump-Stokes beam of light;
• and
• measuring, by the Raman spectroscopy system, the Raman signal.