Laser beam diagnostics are necessary to operate and drive the facility. At the same time, laser beam diagnostics will provide data for the software that is dedicated to “performance”; see BPM, LPOM, and VBL. Alignment diagnostics are necessary for the alignment process. Laser beam diagnostics located at the output of the lasers and at the end of the beam transport sections will be used for driving the facility. Diagnostics inside the beam transport will be used for the alignment process.
There are two types of diagnostics that will be included in the beam transport sections: laser beam diagnostics and alignment diagnostics. All other diagnostics that will be located inside the laser sub-systems or that are specific to some experiments are not part of this package. In addition to laser beam diagnostics at the output of the lasers and at the end of the beam transport sections, there will be other diagnostics inside the beam transport, most probably connected to the image-relay telescopes.
Direct measurement of intensity or peak power is not possible. In order to measure the intensities as required in the ultrashort regime, it is necessary to measure the energy of the beam and its pulse duration and to record the profile of the focal spot. A focal spot measurement station is also necessary.
|
Near Field |
Far Field |
Comment |
Sensor type or device |
|
|
Energy |
X |
X |
Absolute measurement possible |
Full aperture calorimeters |
|
Pulse duration |
X |
Direct measurement of fs pulses not possible; only autocorrelation techniques available. Measuring the spectrum may be required. |
Auto-correlators, spectrometers |
|
|
Focal spot |
X |
Relative measurement. Wavefront sensor may be required in the near field. |
Wavefront sensors, CCD cameras |
