Using two femtosecond pulses for which one is the doubled frequency of the other, I performed a cross-correlation in a BBO crystal and saw very poor contrast in the interference fringes. From this and other measurements it seems the evidence is suggesting that I have some pulse-front tilt occurring.
Does anyone have suggestions for what optics or combination of optics might cause such a thing, and how I could mitigate it without buying expensive FROG devices?
I guess, you do collinear cross-correlation, otherwise the angle between the pulse fronts would be the noncollinear angle.
I general pulse front tilt means angular dispersion. One reason could be a miss-aligned pulse compressor. You can see it, if you scan your beam across the input slit of a spectrograph. If the spectrum changes you have at least spatial chirp. If the spatial chirp increases when you measure further downstream, you have angular dispersion.
Wedges definitely! Waveplates usually quite flat, but color filters could have some small wedges as well. The stretcher - compressor systems of CPA lasers also can be a source of angular dispersion.
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