FASTLITE
45-47 RUE CROULEBARBE
75013 PARIS
FRANCE

Tel.: +33 (0)1 45 30 12 96
Fax : +33 (0)1 45 30 12 97
 
info@fastlite.com
www.fastlite.com
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FREQUENTLY ASKED QUESTIONS: DAZZLER

Q1: Is the acoustic wavefront parallel to the plane of the transducer ?

A1: Yes at the transducer position, but the acoustic wave is later reflected on the optical input face so that the acoustic group velocity in the region of interaction is perpendicular to the optical input face


Q2: Why is the ordinary optical beam deflected ?

A2: The optical output face is not parallel to the input face. The resulting prism effet is designed so that the corresponding dispersion cancels the small angular variations in the Dazzler diffraction angle with wavelength, resulting in negligible angular dispersion in the output beam.


Q3: To get zero dispersion, what dispersion (SOD, TOD, FOD) setting should we have in the Dazzler?

A3: Above the green phase section of the software front panel there is a button labeled selfc (self compensation) which will load the proper programmed dispersions for zero dispersion inside the Dazzler. Starting from this selfc setting, one can alter the polynomial phase terms and/or add an arbitrary phase (edited in file.txt) in order to minimize the pulse duration or generate any spectral phase within the dazzler accessible delay range.


Q4: What are the limits for generating /correcting SOD, TOD and FOD terms?

A4: This depends on your bandwidth, because the limit is defined as a maximum programmable delay. Check that the temporal pattern (time graph) at the bottom right of your panel is kept within the temporal window defined by the blue limit edge. If it exceeds this limit the black and red spectra in the spectrum graph will not coincide.

Q5: Does the Dazzler introduce any kind of spatial chirp ?

A5: As discussed for Q2 there is no angular spatial chirp, i.e. if the beam is focused there is a single focal point whatever the wavelength. However, if the different wavelengths are diffracted in different points in the crystal they are shifted parallel to each other (a walk-off effect). The maximum shear effect is 0.8mm, corresponding to the case where extreme wavelengths are diffracted at each end of a 25mm crystal.