We used the new FLI back illuminated CCD to take the FROG picture. I found this new CCD camera very sensitive to the UV light compared with our old CCD. For the old one, we had to expose about 5 seconds to take Hg I 248 nm line, for this new one, it's only about 30 ms.
When we were taking the FROG images, the signal was very strong. I had to use a ND filter (~0.005 transimission) to attenuate the light. The retrieved data is almost match the raw data. But for the old CCD camera, it's not well to match these data.