Nanoimaging with a compact extreme-ultraviolet laser

Abstract

Images with a spatial resolution of 120-150 nm were obtained with 46.9 nm light from a compact capillarydischarge laser by use of the combination of a Sc-Si multilayer-coated Schwarzschild condenser and a freestanding imaging zone plate. The results are relevant to the development of compact extreme-ultraviolet laser-based imaging tools for nanoscience and nanotechnology. © 2005 Optical Society of America OCIS codes: 180.7460, 110.7440, 140.7240. Rapid progress in nanotechnology and nanoscience creates the need for new practical imaging tools capable of resolving nanometer-sized features. Shortwavelength light provides an opportunity to develop optical imaging systems with the highest resolution. The best resolution so far, 20 nm, has been obtained in imaging with soft-x-ray synchrotron radiation at 2.07 nm wavelength. 1 Submicrometer resolution was obtained with a soft-x-ray recombination laser, 2 and 75 nm resolution was reported with a low-repetitionrate (several pulses per day) laboratory-sized soft-xray laser.3 There is, however, a need for the development of more compact and practical nanometerresolution imaging systems. Toward this goal extreme-ultraviolet (EUV) light from high-order harmonic sources was used to demonstrate imaging systems with a resolution of better than 1 m, 4,5 and soft-x-ray imaging with laser-plasma-based sources has been investigated. [6][7][8] In this Letter we report what is to our knowledge the first demonstration of nanometer-scale imaging with a compact capillary-discharge pumped highrepetition-rate EUV laser. Spatial resolution of the 46.9 nm wavelength system is estimated to be 120-150 nm. This is to our knowledge the highest resolution achieved with a compact high-repetitionrate coherent EUV illumination source. The high average power ͑ϳ1 mW͒ and multihertz repetition rate of the Ne-like Ar capillary discharge laser source that we used 9,10 allowed us to perform real-time imaging, for which the image is continuously updated on the computer screen at the rate of the laser pulses.The imaging system is schematically illustrated in Fig. 1. It consists of a compact capillary-discharge 46.9 nm laser, a Sc-Si multilayer-coated reflective condenser, a zone-plate objective, and a CCD detector. The condenser, the imaged sample, and the objective were mounted onto motorized translation stages that were assembled inside a vacuum chamber connected to the EUV laser source with standard vacuum fittings. The illumination source is a compact capillary-discharge Ne-like Ar laser emitting at a wavelength of 46.9 nm with a pulse duration of ϳ1.2 ns. Its short wavelength, narrow spectral bandwidth, high photon fluence, and beam directionality make this source well suited for microscopy. The spectral bandwidth of the laser is ⌬ / Ͻ10 −4 . 9 The laser's output pulse energy and degree of spatial coherence depend on the capillary discharge length. For this experiment the laser was equipped with an 18 cm capillary discharge tube that provided an average pulse energy of ϳ0.1 mJ. This choice of cap...

Water-window microscopy using a compact, laser-plasma SXR source based on a double-stream gas-puff target

“…Recently different approaches have emerged due to the development of smaller scale short-wavelength sources such as HHG [3], EUV lasers [4] and incoherent laser plasma-based sources [5] that have been successfully used for sub-micrometer resolution imaging. Using radiation from a table-top capillary discharge EUV laser images were obtained with a spatial resolution of 120-150 nm [6]. k = 13.2 nm wavelength radiation from Ni-like cadmium EUV laser allowed for a sub-38 nm resolution nano-imaging [7].…”

Imaging and spectroscopy through plasmonic nano-probe

“…The diffraction limit of UV lights itself is down to 100 nm without a near-field probe. It has been reported that a compact capillary discharge UV laser can realize an imaging with a spatial resolution of 120-150 nm [86,87].…”

Development and optimization of a “water window” microscope based on a gas-puff target laser-produced plasma source

“…Since the '90s, significant efforts were made to bring technical capabilities of synchrotron-based microscopes to the development of compact sources [1]- [8], because that the small size and versatility of compact microscopy system offers the possibility to perform imaging experiments, previously restricted to large-scale facilities, in university laboratories. It was already demonstrated that spatial resolution can be increased in nanoscale imaging systems employing short wavelength radiation such as soft X-ray (SXR) [9].…”