SUPPORT | Frequently Asked Questions
Welcome to the Frequently Asked Questions (FAQ page). Below, we have tried to answer the most common questions visitors to our Web site may have. If you find that your question is not answered on this page, please email us.
• FROG Scan is a real-time scanning FROG measurement system that uses a highly accurate, high speed mechanical optical delay that is at least 10X (ten times) faster than comparable optical delay lines. We seamlessly integrate a fast spectrometer with a 16-bit detector to provide unprecedented dynamic range on a commercial, off-the-shelf system.
Why do I need to know the pulse chirp? Isn’t an autocorrelation good enough?
Well, I guess if all you need is some high-power, wide bandwidth photon hose, then you could just use a power meter and a spectrometer. BUT, if you want to determine peak intensities, need experimental repeatability, are doing pulse shaping, using nonlinear optics, then you need to have an accurate measurement of the pulse shape and chirp. No form of autocorrelation will provide the pulse shape or the chirp. Usually, autocorrelation fools you into thinking that your pulses are shorter than they really are, and that they are smoother than they really are.
What do you mean that the complete range cannot be covered by a “Single Configuration”?
Covering the entire visible range and the entire range of pulse widths is not possible with any one spectrometer and any single doubling crystal. For example, a spectrometer that is ideal for pulse shaping will have a high resolution. However, if a spectrometer has a high resolution, then the spectral window will be too small to cover the spectral range needed for an OPA. Also, there are limitations to the bandwidth of the crystals that are used to generate the FROG signal. Typically, 3 crystals are required to cover the spectral range from ~450 nm to 1800 nm.
Even though we can’t cover the entire range, and you don’t want to buy a FROG Scan for each laser that you have, we have FROG Scan with the idea that you can swap out the crystals and the spectrometers depending on what your current needs are. Thus, FROG Scan can grow with your research group.
What are the differences between FROG Scan and single shot (SS) geometries?
FROG Scan is a scanning, multi-shot geometry. Rather than use two large beams that are crossed at an angle, FROG Scan uses two beams that are focused at the crystal. Advantages of FROG Scan: