Abstract:We have demonstrated a new type of high repetition rate 46.9 nm capillary discharge laser that fits on top of a small desk and that it does not require a Marx generator for its excitation. The relatively low voltage required for its operation allows a reduction of nearly one order of magnitude in the size of the pulsed power unit relative to previous capillary discharge lasers. Laser pulses with an energy of ~ 13 µJ are generated at repetition rates up to 12 Hz. About (2-3) x 10 4 laser shots can be generated with a single capillary. This new type of portable laser is an easily accessible source of intense short wavelength laser light for applications. XUV optical constants by reflectometry using a high-repetition rate 46.9-nm laser," IEEE J. Sel. Top.

We present a laser plasma based x-ray microscope for the water window employing a high-average power laser system for plasma generation. At 90 W laser power a brightness of 7.4 x 10(11) photons/(s x sr x μm(2)) was measured for the nitrogen Lyα line emission at 2.478 nm. Using a multilayer condenser mirror with 0.3 % reflectivity 10(6) photons/(μm(2) x s) were obtained in the object plane. Microscopy performed at a laser power of 60 W resolves 40 nm lines with an exposure time of 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W.

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×...

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The temporal coherence of an injection-seeded transient 18.9 nm molybdenum soft x-ray laser was measured using a wavefront division interferometer and compared to model simulations. The seeded laser is found to have a coherence time similar to that of the unseeded amplifier, ~1 ps, but a significantly larger degree of temporal coherence. The measured coherence time for the unseeded amplifier is only a small fraction of the pulsewidth, while in the case of the seeded laser it approaches full temporal coherence. The measurements confirm that the bandwidth of the solid target amplifiers is significantly wider than that of soft x-ray lasers that use gaseous targets, an advantage for the development of sub-picosecond soft x-ray lasers.