# On-Shot Characterization of Single Plasma Mirror Temporal Contrast Improvement

## TL;DR

This paper presents a novel single plasma mirror setup for improving laser temporal contrast, enabling single-shot measurements of pre-plasma formation and demonstrating enhanced proton acceleration with ultra-thin targets.

## Contribution

The study introduces a compact recollimating plasma mirror and a single-shot spectral interferometry method for real-time contrast measurement during laser-proton experiments.

## Key findings

- Single-shot measurement of plasma mirror trigger point achieved.
- High contrast enhancement allows for ultra-thin target proton acceleration.
- Thinnest targets yield highest proton energies, confirming effective contrast improvement.

## Abstract

We report on the setup and commissioning of a compact recollimating single plasma mirror for temporal contrast enhancement at the Draco 150 TW laser during laser-proton acceleration experiments. The temporal contrast with and without plasma mirror is characterized single-shot by means of self-referenced spectral interferometry with extended time excursion (SRSI-ETE) at unprecedented dynamic and temporal range. This allows for the first single-shot measurement of the plasma mirror trigger point, which is interesting for the quantitative investigation of the complex pre-plasma formation process at the surface of the target used for proton acceleration. As a demonstration of high contrast laser plasma interaction we present proton acceleration results with ultra-thin liquid crystal targets of ~ 1 $\mu$m down to 10 nm thickness. Focus scans of different target thicknesses show that highest proton energies are reached for the thinnest targets at best focus. This indicates that the contrast enhancement is effective such that the acceleration process is not limited by target pre-expansion induced by laser light preceding the main laser pulse.