A dual beam tunable spectrometer comprises a radiation source, generating means, a detector, and a shutter arrangement. The radiation source generates an incident radiative beam. The generating means, which includes an acousto-optic tunable filter, receives the incident radiative beam and generates therefrom a reference beam and a sample beam. The detector detects at least part of the reference beam, and detects at least part of the sample beam emitted from a sample following illumination of the sample with the sample beam. The shutter arrangement includes a first shutter selectively permitting passage therethrough of the part of the reference beam and a second shutter selectively permitting passage therethrough of the part of the sample beam. The shutter arrangement opens the first shutter and closes the second shutter to permit the detector to detect only the part of the reference beam. Similarly, the shutter arrangement closes the first shutter and opens the second shutter to permit the detector to detect only the part of the sample beam.