An optical measurement instrument comprising: - a plurality of sample wells for storing samples (103-109, 203-210) to be measured, - at least one excitation light source (101, 102) each of which being arranged to produce an excitation beam for at least one of samples (103-109, 203-210) to be measured, each sample to be measured being stored in one of the plurality of sample wells, - at least one detector (119, 120) each of which being arranged to detect an emission beam emitted by one of the samples to be measured and to produce a detection signal responsive to the detected emission beam, - a processing device for producing a measurement result for each sample to be measured on the basis of the detection signal related to that sample, and - a temperature sensor arranged to measure sample well specific temperatures from the sample wells, the temperature sensor being capable of measuring different temperatures from different sample wells, and the processing device is arranged to correct the measurement result related to each sample to be measured on the basis of the sample well specific temperature measured from the particular sample well containing that sample, wherein the plurality of the sample wells are movable with respect to the temperature sensor so as to enable the temperature sensor to measure the sample well specific temperatures from more than one sample well, characterized in that the temperature sensor is arranged to measure the sample well specific temperature from a particular one of the sample wells that is in such a mechanical position that the at least one detector (119, 120) is able to detect the emission beam emitted by the sample stored in that particular sample well. - a plurality of sample wells for storing samples (103-109, 203-210) to be measured, - at least one excitation light source (101, 102) each of which being arranged to produce an excitation beam for at least one of samples (103-109, 203-210) to be measured, each sample to be measured being stored in one of the plurality of sample wells, - at least one detector (119, 120) each of which being arranged to detect an emission beam emitted by one of the samples to be measured and to produce a detection signal responsive to the detected emission beam, - a processing device for producing a measurement result for each sample to be measured on the basis of the detection signal related to that sample, and - a temperature sensor arranged to measure sample well specific temperatures from the sample wells, the temperature sensor being capable of measuring different temperatures from different sample wells, and the processing device is arranged to correct the measurement result related to each sample to be measured on the basis of the sample well specific temperature measured from the particular sample well containing that sample, wherein the plurality of the sample wells are movable with respect to the temperature sensor so as to enable the temperature sensor to measure the sample well specific temperatures from more than one sample well, characterized in that the temperature sensor is arranged to measure the sample well specific temperature from a particular one of the sample wells that is in such a mechanical position that the at least one detector (119, 120) is able to detect the emission beam emitted by the sample stored in that particular sample well.