We have acquired images with a spatial resolution better than 38 nm by using a tabletop microscope that combines 13 nm wavelength light from a high-brightness tabletop laser and Fresnel zone plate optics. These results open a gateway to the development of compact and widely available extreme-ultraviolet imaging tools capable of inspecting samples in a variety of environments with a 15-20 nm spatial resolution and a picosecond time resolution.

We have demonstrated near-wavelength resolution microscopy in the extreme ultraviolet.Images of 50 nm diameter nanotubes were obtained with a single ~1 ns duration pulse from a desk-top size 46.9 nm laser. We measured the modulation transfer function of the microscope for three different numerical aperture zone plate objectives, demonstrating that 54 nm half-period structures can be resolved. The combination of near-wavelength spatial resolution and high temporal resolution opens myriad opportunities in imaging, such as the 2 ability to directly investigate dynamics of nanoscale structures. © 2007 Optical Society of America OCIS codes: 180.7460, 110.7440, 140.7240. Conventional visible light microscopy, the most convenient method to image small objects, is limited in resolution to about 200 nm [1]. A direct approach to overcome this limitation is the use of shorter wavelength extreme ultraviolet (EUV) or soft x-ray (SXR) light [2][3][4][5][6][7][8][9][10][11]. The highest spatial resolution achieved to date was obtained at the Advanced Light Source, a third generation synchrotron, where images with 15 nm half-period spatial resolution were acquired in exposure times of several seconds using 1.52 nm wavelength SXR light [2]. The need for compact and more broadly accessible full-field optical microscopes has motivated the development of microscopes based on high-harmonic light sources [5,6], plasma sources [7], and EUV/SXR lasers [8][9][10][11] . However, in all cases the spatial resolution achieved was several times the wavelength and/or required long exposures.In this letter we report what is to our knowledge the first EUV microscope that can obtain images with a spatial resolution approaching the wavelength of illumination, in this case λ = 46.9 nm (hν = 26.4 eV). Moreover, this microscope can obtain high spatial resolution images with a single laser shot, corresponding to ~1 ns temporal resolution, opening the possibility to investigate dynamics of nanoscale structures. This is possible due to the high brightness of the laser source, the high throughput of the optics, and the ability to tailor the spatial coherence of the laser to reduce coherence effects that can degrade single shot images. The entire microscope is extremely compact, occupying an area of 0.4 m × 2.5 m. The combination of these attributes 3 results in the demonstration of a high-resolution tool that can rapidly acquire full-field images for practical laboratory use in a broad range of applications.The microscope is schematically illustrated in Figure 1. Two spherical Sc/Si multilayer mirrors arranged in a Schwarzschild configuration with 13% throughput condense the light from the output of the laser onto the sample. A freestanding objective zone plate lens projects the image onto a charge-coupled device (CCD) detector with 13.5 µm pixels. The laser beam is created via a highly ionized plasma column that is generated by fast electrical discharge excitation of an argon-filled capillary [12]. It emits laser pulses with ~10 µJ of energy (2.4×...

We report the demonstration of a reflection microscope that operates at 13.2 nm wavelength with a spatial resolution of 55+/-3 nm. The microscope uses illumination from a tabletop extreme ultraviolet laser to acquire aerial images of photolithography masks with a 20 s exposure time. The modulation transfer function of the optical system was characterized.

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...