GEMINI MEASURES FLUORESCENCE SPECTRA WITH UNMATCHED SPEED, RESOLUTION AND SENSITIVITY
COMPARISON WITH MONOCHROMATORS
The GEMINI is designed to be added to your setup to extract the spectrum of any light source, coherent or not. It outperforms monochromators, since GEMINI overcomes their main drawbacks in terms of low throughput, fixed spectral resolution and limited spectral coverage.
We performed a direct comparison of the performances of a standard monochromator and NIREOS’ GEMINI system in terms of resolving the spectrum of the fluorescence emitted by a fluorescent sample. The emitted light was collected at 90° by a lens, sent to either a monochromator or NIREOS’ GEMINI interferometer and detected by the same photomultiplier (PMT).
As can be seen in the following graph, NIREOS’ GEMINI interferometer can reach the same signal to noise (S/N) ratio provided by a monochromator employing ~100 times lower excitation light power, thus preserving the sample against damage. Conversely, for a given excitation power and integration time, NIREOS’ GEMINI interferometer can reach an order of magnitude higher S/N. This also translates in ~100 times faster acquisition time for a given desired S/N and excitation power.
1) Time-Resolved Emission Spectra (TRES)
NIREOS’ compact and ultra-stable GEMINI interferometer can be employed to map a sample’s fluorescence as a function of emission wavelength and decay time with both high temporal and spectral resolution (known under the name TRES).
The sample is illuminated with a pulsed laser in resonance with its optical absorption and the generated fluorescence photons are detected by a single-photon detector, such as a photomultiplier (PMT) or a single-photon avalance detector (SPAD). NIREOS’ GEMINI interferometer provides the spectral resolution, via a Fourier transform (FT) approach, while a time-correlated single photon counting (TCSPC) unit brings the temporal resolution to the table.
This system is remarkably simple, as it only requires the addition of the GEMINI to a standard single-pixel TCSPC system, and it shows a readily adjustable spectral resolution with inherently broad bandwidth coverage.