A birefringent interferometer for measuring photoluminescence properties of samples

Data di pubblicazione






Data di priorità



Italy, US, EP, PCT


Politecnico di Milano


Department of Physics


Dario Polli; Giulio Cerullo; Fabrizio Preda; Antonio Perri; Jürgen Hauer


This innovative device enables one to measure fluorescence Excitation–Emission–Matrix (EEM) and, in parallel, absorption, fluorescence and fluorescence excitation spectra of samples over a broad bandwidth in any spectral region. The EEM and the absorption spectra are retrieved by means of a Fourier transform of the interference signal between two replicas of the excitation light, whose relative delay is scanned by changing the insertion of a birefringent wedge. This device requires a light source (i.e. a lamp or a laser), one or two polarizers, two birefringent wedges, one birefringent plate, one spectrometer and at least one detector. A modified device based on the very same principle of measurement comprises a light source, three or four polarizers, four birefringent wedges, two birefringent plates and at least one detector. A third version of the device comprises a light source, at least two polarizers, two birefringent wedges, one birefringent plates and at least one detector.

Campo di applicazione

This device will be mostly considered and exploited in biological and pharmaceutical areas, where fluorescence and EEM are performed regularly in order to retrieve crucial information about the sample chemical composition. The EEM has been also used to detect and quantitatively assess dissolved organic matter in water and contaminants of jet fuels with aero-turbine lubricating oil, indicating that this device can be exploited in general industry quality test with unprecedented performances.


<p> This device enhances the sensitivity, the resolution and shortens the acquisition time of EEM compared to currently commercial available devices. </p> <p> <ul> <li> This device does not require a monochromator in the excitation beam to select sequentially different excitation wavelength. On the contrary, it employs a common–path interferometer that modulates in parallel a broadband excitation light; </li> <li> This device does not require a monochromator in the detection beam to select sequentially different detection wavelength; </li> <li> This device illuminates the sample and collects the emitted fluorescence with all the light colors simultaneously, so that it measure the entire EEM at once; </li> <li> With this device it is possible to vary the excitation spectral resolution just by varying the scan range of the moving wedge in the excitation beam; </li> <li> Since this device is based on the employment of at least one interferometer instead of monochromators, the throughput is dramatically increased (Jacquinot’s advantage), so that higher sensitivities can be reached. </li> </ul> </p>

Stadio di sviluppo

Working prototype