Single-Shot Real-Time Ultrafast Imaging of Femtosecond Laser Fabrication

Abstract

Femtosecond laser fabrication outperforms the traditional fabrication techniques with high precision, high efficiency, low collateral damage and wide applicability, which has shown to be a powerful tool in precision machining. Imaging the ultrafast dynamics of femtosecond laser fabrication is necessary for understanding the processing mechanism and for establishing the corresponding physical models. Up to now, ultrafast measurement techniques based on the pump−probe strategy are the most used methods. However, they are limited by laser energy stability and materials surface uniformity, which have a heavy impact on the dynamic measurement precision of femtosecond laser fabrication. To overcome this limitation of the traditional pump−probe techniques, we developed chirped spectral mapping ultrafast photography (CSMUP), which can achieve single-shot real-time ultrafast imaging with a frame rate of about 250 billion frames per second (temporal frame interval of 4 ps) and a spatial resolution of less than 833 nm. We experimentally imaged the dynamics of femtosecond laser ablation in silicon under a 400 nm femtosecond laser exposure with CSMUP, and the experimental result agreed well with previous theoretical models. CSMUP provides a new strategy to improve the efficiency and accuracy of femtosecond laser fabrication by a single-shot dynamic measurement of the interaction between the femtosecond laser and materials, and it is expected to work as a real-time detection method for various ultrafast phenomena.

Exploring Femtosecond Laser Ablation by Snapshot Ultrafast Imaging and Molecular Dynamics Simulation

“…To overcome these shortcomings, here we conduct a single-shot chirped spectral mapping ultrafast photography (CSMUP) to record the transient images of single-pulse FLA on a bulky gold with a temporal range covering about 100 ps. The principle of CSMUP can be found in our previous work [37]. CSMUP utilizes a broadband laser pulse with temporally positive chirp to illuminate the ablation area and employs a hyperspectral camera as an image receiver.…”

Acousto-optically driven single-shot ultrafast optical imaging

“…Nevertheless, such frame rates are not sufficient to resolve many ultrafast events and single-shot techniques with frame intervals in the picosecond range -or less -are required for imaging e.g. laser-induced phenomena [11,12] or light propagation itself [13,14]. Single-shot methods can be separated between passive and active detection and further between direct imaging and reconstruction imaging [15,6], each family having its strengths and limitations.…”

Lensless ultrafast optical imaging

“…High-speed transient dynamic phenomena widely exist and affect nearly all areas of human society, such as industry, defense, biomedicine, and scientific research 1 , 2 . Visualization of the high-speed transient dynamic process plays a pivotal role in discovering, understanding, and applying the underlying laws 3 – 7 . Yet, capturing and recording blur-free images of the transient dynamics requires high temporal resolution with balanced spatial resolution, which imposes demanding conditions on imaging acquisition techniques.…”

“…To circumvent the technical hurdles from the pump-probe method, various single-shot ultrafast optical imaging solutions have been developed in recent years 3 – 7 , 16 . These technologies enable the visualization of non-repetitive ultrafast dynamic processes in real time with an imaging speed of 100 Mfps or higher.…”