The acceleration of super-heavy ions (SHIs, mass number of about 200) from plasmas driven by ultrashort (tens of femtoseconds) laser pulses is a challenging topic awaiting a breakthrough. Detecting and controlling the ionization process and adopting the optimal acceleration scheme are crucial for the generation of highly energetic SHIs. Here, we report the experimental results on the generation of deeply ionized super-heavy ions (Au) with unprecedented energy of 1.2 GeV utilizing ultrathin targets and ultrashort laser pulses at an intensity of ${10}^{22}\mathrm{W}/{\mathrm{cm}}^2$. A novel self-calibrated diagnostic method was developed to acquire the absolute energy spectra and charge-state distributions of Au ions abundant at the charge state of $51+$ and extending to $61+$. The measured charge-state distributions supported by 2D particle-in-cell simulations serve as an additional tool to inspect the ionization dynamics associated with SHI acceleration, revealing that the laser intensity is the crucial parameter over the pulse duration for Au acceleration. Achieving a long acceleration time without sacrificing the strength of the acceleration field by utilizing composite targets can substantially increase the maximum energy of Au ions.

The use of vortex laser beams has increased in various areas of optics and photonics, necessitating enhanced beam quality for wide usage. In the field of high-power lasers, a range of methods to implement vortex laser beams has been proposed. Nonetheless, enhancing beam quality becomes more challenging as the laser power increases. This study presents the successful implementation of a high-quality, high-intensity vortex laser beam exceeding 10²⁰W/cm²—an essential advancement for enhancing the performance and applicability of high-power lasers. We achieved this by integrating a spiral phase mirror (SPM) with an orbital angular momentum of l=1, specially designed for the vortex beam, along with an adaptive optical system, into a 150-TW femtosecond Ti:sapphire laser. Importantly, SPM, featuring a modulation structure to correct for a 45° incidence angle, was utilized to produce the vortex beam. The adaptive optical system, comprising a Shack–Hartmann wavefront sensor and a deformable mirror, employed a feedback loop to correct wavefront aberrations distorting the vortex beam. Notably, the negligible difference between the Hartmanngrams of the Gaussian and vortex beams (l=1) allowed the Gaussian beam’s Hartmanngram to serve effectively as the input reference for wavefront correction, resulting in a successfully corrected vortex beam wavefront. Experimental results, both pre- and post-wavefront correction, were compared with simulation results obtained via field-tracing. The peak intensity of the focused high-quality vortex laser beam ultimately reached 1.8×10²⁰W/cm², exceeding previously reported experimental results. The results of this study could significantly contribute to the exploration of high-intensity angular momentum transfer in relativistic laser-plasma interactions.

Photothermal imaging is useful for detecting individual nanoparticles and obtaining the absorption spectra. This study presents a wide‐field photothermal reflectance spectroscopy technique achieved by incorporating a pump beam, a probe beam, and a charge‐coupled device (CCD) camera into a commercial microscopic setup. The presented design does not require precise alignment between the pump and the probe beams and enables the observation of numerous individual nanoparticles during image acquisition. Despite the use of a simple imaging processing method, i.e., a four‐bucket method using a CCD camera, sufficient sensitivity for the spectral imaging of a single gold nanorod (20 nm diameter and 84 nm length) is demonstrated. Numerous individual nanoparticles within a wide field of view (240 μm × 180 μm) are detected in an image captures at an imaging measurement speed of 0.02 mm ² min ⁻¹ . Furthermore, the proposed photothermal reflectance spectroscopy technique can detect the variation in the absorption peak of the measured spectra depending on the aspect ratio of individual nanoparticles within a spectral resolution of 1 nm.

Wavelength-tunable spiral-phase-contrast (SPC) imaging was experimentally accomplished in the visible wavelengths spanning a broad bandwidth of ∼200 nm based on a single off-axis spiral phase mirror (OSPM). By the rotation of an OSPM, which was designed with an integer orbital angular momentum (OAM) of l = 1 at a wavelength of 561 nm and incidence angle of 45°, high-quality SPC imaging was obtained at different wavelengths. For the comparison with wavelength-tunable SPC imaging using an OSPM, SPC imaging using a spiral phase plate (manufactured to generate an OAM of l = 1 at 561 nm) was performed at three wavelengths (473, 561, and 660 nm), resulting in clear differences. Theoretically, based on field tracing simulations, high-quality wavelength-tunable SPC imaging could be demonstrated in a very broad bandwidth of ∼400 nm, which is beyond the bandwidth of ∼200 nm obtained experimentally. This technique contribute to developing high-performance wavelength-tunable SPC imaging by simply integrating an OSPM into the current optical imaging technologies.

Wavelength-tunable optical vortices with a topological charge equal to l = 1 of orbital angular momentum (OAM) were experimentally realized using a single off-axis spiral phase mirror (OSPM) with lasers of various visible-light wavelengths. Using an OSPM designed for 561 nm and an incidence angle of 45°, circular doughnut-shaped l = 1 optical vortices were obtained at 561, 473, and 660 nm by rotating the OSPM to modify the laser incidence angle. Wavelength-tunable l = 1 optical vortices were obtained at the respective incidence angles of 45°, 53.4°, and 33.7°, because the effective geometrical thickness of the OSPM, which determines the order of OAM, was identical at each wavelength. This flexible OSPM which operates over a wide wavelength range will provide continuously wavelength-tunable optical vortices for applications in the fields of advanced optics and photonics in which optical vortices with wide wavelength tunability are in demand.

We developed a 193-nm deep ultraviolet (DUV) microscope system based on the reflection mode for a precise inspection of various types of defects/cracks on large optical surfaces of the order of one meter in size. Without preprocessing the sample at room temperature and atmospheric pressure, which is commonly necessary for electron microscopy, the reflective 193-nm DUV microscope was used to directly observe optical surface defects in a manner similar to conventional optical microscopes. In addition, the limitations on the selection of materials and thickness of optical samples of transmittive DUV microscopes were overcome. DUV microscope imaging and the analysis on the spatial resolution were verified using a 1D grating structure with a 225-nm line width. This system could be widely applied as an inspection tool because it provides high resolution at the 200-nm scale that is close to the diffraction limit of a 193-nm DUV beam. In the near future, it is expected that our system would be extended to nano/bio imaging as well as the inspection of large optical surfaces.