1 Abstract—The XM-1 soft x-ray microscope is a user-dedicated facility located at the Advanced Light Source at Lawrence Berkeley National Laboratory and has recently been established as a tool for high-resolution imaging of magnetic domains. It is a conventional full field transmission microscope which is able to achieve a resolution of 25 nm by using high-presicion zone plates. It uses off-axis bend magnet radiation to illuminate samples with elliptically polarized light. When the illumination energy is tuned to absorption edges of specific elements, it can be used as an element-specific probe of magnetism on the 25 nm scale with contrast provided by magnetic circular dichroism. The illumination energy can be adjusted between 250-850 eV. This allows magnetic imaging of elements including chromium, iron and cobalt. The spectral resolution has been shown to be E/ΔE = 500 – 700. This spectral resolution allows a high sensitivity so that magnetization has been imaged within layers as thin as 3 nm. Since this is a photon based magnetic microscopy, fields can be applied to the sample even during imaging without affecting the spatial resolution. The current system can apply in-plane or out- of-plane fields of a few kOe. Index Terms—high-resolution, magnetic imaging, x-ray microscopy. I. INTRODUCTION he XM-1 X-ray microscope is located at the Advanced Light Source and provides high spatial resolution imaging of samples. The design allows a high throughput of a variety of samples in a wide variety of applications including Biology, Environmental Science, Materials Science, and Magnetic Imaging [1,2,3]. Magnetic imaging is accomplished by transmission through the sample with elliptically polarized light. The large contrast Manuscript received Oct 13, 2000. This work was supported in part by the U.S. Department of Energy office of Basic Energy Science. G. Denbeaux is with Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA (telephone: 510-486-4051, email: gpdenbeaux@lbl.gov). P. Fischer is with Universität Würzburg, Würzburg Germany (telephone: +49 931 888 5870, email: peter.fisher@physik.uni-wuerzburg,de) G. Kusinski is with UC Berkeley and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (telephone: 510- 495-2455, email: kusinski@uclink4.berkeley.edu). M. A. Le Gros is with Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA (telephone: 510-486-6892, email: malegros@lbl.gov). A. Pearson is with Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA (telephone: 510-486-4079, email: aelucero@lbl.gov). D. Attwood is with Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA (telephone: 510-486-4463, email: dtattwood@lbl.gov) for magnetic materials is provided by x-ray magnetic circular dichroism (X-MCD). This allows element-specific imaging of the magnetization within samples with high sensitivity. Since this is a photon based technique, magnetic fields can be applied to the sample during imaging without affecting the image formation. The illumination is provided by bend magnet radiation from the Advanced Light Source which is projected onto the sample through a condenser zone plate lens. The present condenser zone plate has a diameter of 9 mm, an outer zone width of 55 nm, and 41,000 zones. The illumination energy can be changed by the linear monochromator, which is composed of the condenser zone plate and a pinhole near the sample plane (typically 100 microns from the sample plane). Due to the chromatic aberrations of zone plates, simply shifting the distance between the condenser and the pinhole/sample plane shifts the illumination energy, which can be changed between 250-900 eV, and has been measured to have a spectral resolution of E/ΔE = 500 - 700 [4]. The radiation passing through the sample is projected through the micro zone plate onto a CCD camera. The present micro zone plate has an outer zone width of 25 nm and a diameter of 63 microns. Both the micro zone plate and the condenser zone plate were fabricated by electron beam lithography by Erik Anderson at the Nanofabrication Laboratory in the Center for X-ray Optics [5]. The high-precision optics allow a high spatial resolution which has been shown to be 25 nm [6]. A series of test patterns with various lines and spaces has been imaged. A test pattern with 25 nm lines and 25 nm spaces can easily be resolved with a contrast of 24 %. The CCD camera is a 1024 x 1024 pixel array which is back-thinned and back-illuminated. It has a quantum efficiency of approximately 60-70% in the range of energies that the microscope operates. Samples positions and focus can be pre-selected in a custom Zeiss Axioplan visible light microscope which is mutually indexed with the sample stage of XM-1. X-Y position accuracy is typically 2 microns over a 3 mm field with focal accuracy of 1 micron. This helps to allow the high throughput of samples. During a typical day, hundreds of images are collected. The field of view of the microscope is 10 microns, so for larger samples, there is an automated montage assembly [7]. This automated process builds a larger image based on a series of subfields. Using cross-correlation techniques, the smaller images are placed at the proper locations creating a nearly A Full Field Transmission X-ray Microscope as a tool for High-Resolution Magnetic Imaging Gregory Denbeaux, Peter Fischer, Greg Kusinski, Mark Le Gros, Angelic Pearson, David Attwood T