FemtoFrame-II

SPECIAL FEATURES

• UV extended spectral range using white-light generator
• Excellently compatible with Rainbow 20F tunable laser source
• Optimized for Ti:Sa-kHz Amplified Systems
• Minimum probe pulse chirp
• Dispersion-free mirror optics
• Sub-100fs time resolution
• Easy alignment

APPARATUS

- femtosecond white-light generator

- frequency doubler for Ti:sapphire laser;

- optical delay line with 2-ns travel range and 3 fs resolution

• Optical units:
• Precise imaging spectrometer
• Multi channel CCD detector head, connected to a PC via USB2.0
• Optical shutters or optical chopper,
• Stand-alone or LabView^TM software

FemtoFrame-II is applied in femtosecond or picosecond pump – probe absorption spectroscopy for sensitive absorption changes (optical density changes) measurements. The large area CCD detector head is placed after an imaging spectrometer to measure simultaneously probe and reference pulses, originating from femtosecond white-light continuum and split by a broadband beam splitter.

The exposure conditions are highly variable by the user allowing great flexibility in matching the individual requirements of the sample. The usual opening time for the optical shutter(chopper) is 20 - 120ms and the detection system accumulates several tens of pulses before readout. For increasing the S/N ratio several readout cycles can be applied and typically 4-10 seconds are taken for the spectra averaging.

3D spectral image OD (λ,t) is formed by scanning the optical delay line. Several scans can be averaged to minimize the influence of the laser instabilities.

FemtoFrame-II gives 1.2x10^-4 OD (rms) sensitivity, measured as a base line noise for 5 seconds averaging time.

SOFTWARE FEATURES

• White light adjustment mode
• Real time view mode for easy alignment
• Group velocity (chirp) correction
• Transient absorption spectra preview and 2D/3D export