# Z-scan confocal method for indirect focusing location

## TL;DR

The paper introduces the z-scan confocal method, a technique for accurately locating and sizing the focal spot of ultrashort laser pulses, enabling fast target positioning in laser plasma experiments.

## Contribution

It presents a novel, rapid method for determining the absolute focal position and size, improving automation in laser plasma target alignment.

## Key findings

- Accurately locates the focal spot in ultrashort laser pulses.
- Enables fast positioning of targets in laser experiments.
- Demonstrates measurement of defocusing in a rotating disc.

## Abstract

We present a new technique that we have defined as the z-scan confocal method to determine the absolute location and size of the focal spot in a tight focused ultrashort laser pulse. The method permits to accurately position a target in the focal spot with a fast response. The technique is designed to help to automatize the location of an overdense target in focus in a laser plasma experiment. The method allows for a fast localization of the focal position and the relative motion of the target with respect to it. As an example of the capacities we measure the defocusing of a fast rotating disc in several radius to reconstruct the motion of the disc at focus.

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Source: https://tomesphere.com/paper/1704.08766