A measurement system (5) comprises a radiation source (10) and a detection system (15), wherein the radiation source is arranged such that radiation from the radiation source is incident on a sample (25) and the detection system is configured to receive at least part of the radiation via the sample, wherein the system is reconfigurable so as to vary a path length that the radiation travels through the sample and/or a reflectance of at least one surface upon which the radiation is incident after passing through at least part of the sample. A property of the sample may be determined based on at least the first and second measurements.