Combination of two led and open port calibration

A method of calibrating a sensing device, the sensing device comprising:

• a. at least one detector element configured for generating at least one detector signal in response to an illumination of the detector element by incident light;
• b. at least one light source configured for emitting light in at least one optical spectral range;
• c. at least one sample interface configured for allowing light from the light source to illuminate at least one sample and configured for allowing light from the sample to propagate to the detector element;
• d. at least one first optical path, wherein the first optical path is configured for allowing light emitted from the light source to propagate to the detector element without passing the sample interface;
• and
• e. at least one second optical path, wherein the second optical path is configured for allowing light emitted from the light source to propagate to the detector element by passing the sample interface at least once,
• the method comprising:
• I. illuminating the detector element via the at least one first optical path to obtain at least one first detector signal S1;
• II. illuminating the detector element via the at least one second optical path with no sample applied to the sample interface to obtain at least one open port detector signal S2;open;
• and
• III. determining at least one item of operation calibration information by using the first detector signal S1, the open port detector signal S2;open and at least one item of factory calibration information, wherein the item of factory calibration information comprises a predefined relation between the open port detector signal S2;open and a reference signal of the second optical path.