Raman spectroscopy method and apparatus

A method of performing Raman spectroscopy comprising:

• generating wavelength shifted excitation light for exciting a Raman response from at least one sample, wherein the wavelength shifted excitation light comprises at least two excitation wavelengths;
• providing the wavelength shifted excitation light to the at least one sample and collecting signal light from the at least one sample;
• obtaining response signals from the collected signal light, wherein obtaining the response signals from the collected signal light comprises performing a plurality of measurements corresponding to a plurality of excitation wavelengths;
• processing the obtained response signals to determine a Raman response and a fluorescence response, wherein determining the Raman response uses at least one characteristic of an expected Raman response to the wavelength shifted excitation light and wherein determining the fluorescence response uses at least one characteristic of an expected fluorescence response to the shifted excitation light, and wherein processing the obtained response signals comprises applying a model that permits changes in the intensity of the Raman response and/or the fluorescence response over the plurality of measurements.

A method of performing Raman spectroscopy comprising:

• generating wavelength shifted excitation light for exciting a Raman response from at least one sample, wherein the wavelength shifted excitation light comprises at least two excitation wavelengths;
• providing the wavelength shifted excitation light to the at least one sample and collecting signal light from the at least one sample;
• obtaining response signals from the collected signal light;
• processing the obtained response signals to determine a Raman response and a fluorescence response, wherein determining the Raman response uses at least one characteristic of an expected Raman response to the wavelength shifted excitation light and wherein determining the fluorescence response uses at least one characteristic of an expected fluorescence response to the shifted excitation light, and wherein processing the obtained response signals comprises at least one of a), b:
• a) modelling a bias parameter representative of additive noise from the sensor;
• b) applying a further constraint to ensure that the determined Raman response is non-negative.

A Raman spectroscopy apparatus comprising:

• a shifted wavelength excitation light generator configured to generate shifted wavelength excitation light having at least two excitation wavelengths, wherein the generated shifted wavelength excitation light is for exciting a Raman response in at least one sample;
• a delivery path configured to deliver the generated shifted wavelength excitation light to the at least one sample;
• a collection path configured to collect signal light from the at least one sample;
• a response measurement device for obtaining response signals from the collected signal light;
• and
• a processing resource configured to process the obtained response signals to determine a Raman response and a fluorescence response, wherein determining the Raman response uses at least one characteristic of an expected Raman response to the wavelength shifted excitation light and wherein determining the fluorescence response uses at least one characteristic of an expected fluorescence response to the shifted excitation light, wherein the processing resource is configured to determine the Raman response by performing a model fitting process comprising determining a set of model parameters to minimize a loss function, wherein a value of the loss function is dependent on an estimated Raman response and an estimated fluorescence response.