An apparatus (500) for spectral measurements comprises: - an illuminating unit (110) to form
narrowband light pulses (B2t1, B2t2) at different wavelengths (λ1,λ2) for illuminating an object (OBJ1) with the
narrowband light pulses (B2t1, B2t2) - a sensor (SEN1) to detect light (B3) received from the object (OBJ1), - a
control unit (CNT1) to control operation of the sensor (SEN1), wherein the illuminating unit (110) comprises: - a
broadband light source (LS1) to generate
broadband light pulses (B1), - a Fabry-Perot interferometer (FPI1) to form
narrowband light pulses (B2) by filtering the
broadband light pulses (B1), wherein the
broadband light source (LS1) is arranged to generate a first broadband light pulse (B1t1) at a first trigger time (t1), and to generate a second broadband light pulse (B1t2) at a second trigger time (t2), wherein the Fabry-Perot interferometer (FPI1) is tunable by moving a mirror (M2) of the Fabry-Perot interferometer (FPI1), wherein the illuminating unit (110) is arranged to operate such that a movement of the mirror (M2) is not stopped between the first trigger time (t1) and the second trigger time (t2), wherein a
start time (tA1) of a first
exposure time (ΔtEX1) of the sensor (SEN1), and a duration of the first
exposure time (ΔtEX1) are controlled such that the illuminating unit (110) forms the first broadband light pulse (B1t1) and the second broadband light pulse (B1t2) during the first
exposure time (ΔtEX1).