Spectrometer with built-in calibration path

An in-use calibration method for a spectrometer device, the method comprising:

• a) providing the at least one spectrometer device comprising at least one optical measurement element and at least one optical calibration element having different optical properties, wherein the spectrometer device comprises at least two detectors, wherein the first detector is configured for being illuminated by emitted light via at least one optical measurement path and wherein the second detector is configured for being illuminated by emitted light via at least one optical calibration path;
• b) providing at least one sample;
• c) performing at least two measurements using the spectrometer device, wherein one of the measurements is performed with the sample and one of the measurements is performed without the sample,
• i. wherein performing the measurement with the sample comprises illuminating the first detector of the spectrometer device via the optical measurement path by using the optical measurement element, the optical measurement path comprising at least one reflection at the at least one sample, and
• ii. wherein performing the measurement without the sample comprises illuminating the second detector via the optical calibration path independent from the optical measurement path by using the optical calibration element, the optical calibration path comprising at least one interaction with the optical calibration element without an interaction the sample and wherein the optical calibration path is arranged within the spectrometer device, specifically within a housing of the spectrometer device;
• wherein the two measurements are performed simultaneously;
• d) generating by the at least one detector at least one first detector signal Sd1 according to the measurement without the sample and at least one second detector signal Sd2 according to the measurement with the sample;
• and
• e) deriving at least one calibrated optical property of the at least one sample from the first detector signal Sd1 and the second detector signal Sd2.