FROG Scan


	Mesa Photonics


	Latest News

	September 1, 2007 We are pleased to announce our new ultrafast laser pulse measurement system: FROG Scan


	January 1, 2007 Version 7 of VideoFROG has just been released. With a new look and user interface, pulse measurement has never been easier.


	News

	Mesa Photonics is pleased to announce the issuing of US Patent 7,130,052.


		FROG Scan measures pulses with time-bandwidth products up to 100!

	We couple our VideoFROG software with an advanced high-speed translation stage to provide fast, versatile and high range pulse measurement. With our FROG Scan, you can tweak a laser system or measure highly chirped pulses to calculate the amount of dispersion compensation you might need for recompression. Measure a short pulse that has been chirped out to several picoseconds, or measure pulses as short as 15 fs. The spectrometer and crystals are field changeable so you can tailor FROG Scan to your exact needs. Check out our FROG Scan Data page!

FROG Scan is a new workhorse pulse measurement system. Whether you are tweaking up a laser system or measuring shaped pulses, FROG Scan is just right for your needs. Our new FROG Scan pulse measurement system can measure pulses from 450 nm to 1800 nm less than 15 fs* in length to more than 10 picoseconds. The high speed translation stage coupled with our VideoFROG software (included with the system) means that FROG Scan can make pulse measurements at better than 2 Hz (32 x 32 grid, ~70 spectra/second).


	Our new FROG Scan is a scanning second harmonic generation (SHG) FROG system that uses what is known as a “multi-shot” configuration. That is, like a standard autocorrelator, it uses a translation stage to scan through different pulse delays. The translation stage uses a new technology that gives it unprecedented speed and accuracy.

		Shown on right is a picture of the FROG Scan. Your laser beam enters from the right through two alignment irises. A beam splitter sends one pulse replica though a fixed delay. The other replica is sent to the high-speed, high accuracy translation stage. Both beams are reflected back to a focussing mirror to be focussed into the second harmonic generation crystal. The SHG signal from the pulse overlap region is spectrally resolved using an Ocean Optics USB4000 or USB2000 spectrometer, which can be changed as your pulse measurement needs change.

		Pictured to the right is a view of the software front panel. (For more example data, click here.) It is the same simple VideoFROG interface that we are known for. Shown is measured pulse with high order spectral chirp from a pulse shaper. FROG scan can easily measure complex pulses. The ease of use of our device is easy to see. Do not be fooled by it’s simplicity, however. Because of your seamless ability to change the time span of a scan, a single configuration of our FROG Scan can replace 3 or more competing FROG devices.

Our device can also accomplish measurements competing devices cannot do. For example, just try to measure a 20 fs laser pulse chirped to 400 fs with competing FROG devices. You can’t. The combination of the pulse length and the bandwidth cannot be handled by any device that uses the SHG crystal as the dispersive element. FROG Scan makes such a measurement easy. Time scan ranges can be changed on the fly, and wavelength too--all by software control. A single USB connection to your computer is all that is required. With software included, it is the best value available for pulse measurement.


	The 16-bit spectral data obtained by the USB4000 spectrometer also provides unprecedented dynamic range and sensitivity. Changeable integration time means that weak signals can be integrated.


	Specifications

Input Pulse Wavelength Range	450 nm - 1800 nm
Pulse Length Range	< 15 fs - 10 ps (see below)
Temporal Range	30 ps
Temporal Resolution	2 fs or better
Delay Increment	1 fs
Spectral Resolution	0.20 nm - 1 nm
Spectral Range	100 nm - 600 nm
Pulse Complexity	TBWP > 50
Intensity Accuracy	2%
Phase Accuracy	0.01 radians
Realtime Sensitivity (I_peakI_ave)	4 W²
Averaged Sensitivity (I_peakI_ave)	< 0.1 W²
Input Beam Size	2 - 4 mm collimated
Nominal Polarization	Horizontal (Vertical by rotating crystal)
Acquisition Speed	> 1 Hz 64 x 64 grid
Spectra required for measurement	number in grid
Size on table	6.3 in x 12 in (16 cm x 30.5 cm)
Software	VideoFROG -- Included in price


	The complete range cannot be covered with a single configuration. Spectrometer ranges and resolution determine the wavelength range and the longest transform limited pulse that can be measured, respectively. Crystal and spectrometers are user/field changeable. Spectrometer changes are automatically recognized by the software.


	*A 30 micron thick crystal comes standard. The time smearing factor on FROG Scan is about 4 fs. Therefore, a 10 fs pulse will be measured to be (10^2 + 4^2)^0.5 = 10.8 fs in length. If this is acceptable, a thinner crystal can be ordered. Pulses as short as 12.5 fs have been measured using the 30 micron crystal.


	mesaphotonics.com