Jonathan L. Kirschman

Bio: Jonathan L. Kirschman is an academic researcher from Lawrence Berkeley National Laboratory. The author has contributed to research in topics: Metrology & Calibration. The author has an hindex of 5, co-authored 7 publications receiving 257 citations.

Sub-microradian surface slope metrology with the ALS Developmental Long Trace Profiler

Abstract: A new low-budget slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently brought to operation at the ALS Optical Metrology Laboratory. The design, instrumental control and data acquisition system, initial alignment and calibration procedures, as well as the developed experimental precautions and procedures are also described in detail. The capability of the DLTP to achieve sub-microradian surface slope metrology is verified via cross-comparison measurements with other high-performance slope measuring instruments when measuring the same high-quality test optics. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.

Performance of the upgraded LTP-II at the ALS Optical Metrology Laboratory

Abstract: The next generation of synchrotrons and free electron laser facilities requires x-ray optical systems with extremely high performance, generally of diffraction limited quality. Fabrication and use of such optics requires adequate, highly accurate metrology and dedicated instrumentation. Previously, we suggested ways to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used to characterize x-ray optics at long spatial wavelengths. The main way is use of a CCD detector and corresponding technique for calibration of photo-response non-uniformity [J. L. Kirschman, et al., Proceedings of SPIE 6704, 67040J (2007)]. The present work focuses on the performance and characteristics of the upgraded LTP-II at the ALS Optical Metrology Laboratory. This includes a review of the overall aspects of the design, control system, the movement and measurement regimes for the stage, and analysis of the performance by a slope measurement of a highly curved super-quality substrate with less than 0.3 microradian (rms) slope variation.

Optimal tuning and calibration of bendable mirrors with slope-measuring profilers

Abstract: We describe a technique to optimally tune and calibrate bendable X-ray optics for submicron focusing. The focusing is divided between two elliptically cylindrical reflecting elements, a Kirkpatrick-Baez pair. Each optic is shaped by applying unequal bending couples to each end of a flat mirror. The developed technique allows optimal tuning of these systems using surface slope data obtained with a slope-measuring instrument, the long trace profiler. Because of the near linearity of the problem, the minimal set of data necessary for the tuning of each bender consists of only three slope traces measured before and after a single adjustment of each bending couple. The data are analyzed with software realizing a method of regression analysis with experimentally found characteristic functions of the benders. The resulting approximation to the functional dependence of the desired shape provides nearly final settings. Moreover, the characteristic functions of the benders found in the course of tuning can be used for retuning to a new desired shape without removal from the beamline and remeasuring. We perform a ray trace using profiler data for the finally tuned optics, predicting the performance to be expected during use of the optics on the beamline.

Flat-field calibration of CCD detector for long trace profiler

Abstract: The next generation of synchrotrons and free electron lasers requires x-ray optical systems with extremely high-performance, generally, of diffraction limited quality. Fabrication and use of such optics requires highly accurate metrology. In the present paper, we discuss a way to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used at synchrotron facilities to characterize x-ray optics at high-spatial-wavelengths from approximately 2 mm to 1 m. One of the major sources of LTP systematic error is the detector. For optimal functionality, the detector has to possess the smallest possible pixel size/spacing, a fast method of shuttering, and minimal nonuniformity of pixel-to-pixel photoresponse. While the first two requirements are determined by choice of detector, the non-uniformity of photoresponse of typical detectors such as CCD cameras is around 2-3%. We describe a flat-field calibration setup specially developed for calibration of CCD camera photo-response and dark current with an accuracy of better than 0.5%. Such accuracy is adequate for use of a camera as a detector for an LTP with performance of ~0.1 microradian (rms). We also present the design details of the calibration system and results of calibration of a DALSA CCD camera used for upgrading our LTP-II instrument at the ALS Optical Metrology Laboratory.

New procedures for the adjustment of elliptically bent mirrors with the long trace profiler

Abstract: Micro-focusing is widely applied at soft and hard x-ray wavelengths. One typical method, in addition to zone plates, is to split the focusing in the tangential and sagittal directions into two elliptically cylindrical reflecting elements, the so-called Kirkpatrick-Baez (KB) pair. In the simplest case each optic is made by grinding and polishing a flat, and applying unequal bending couples to each end. After briefly reviewing the nature of the bending, we show two new methods for optimal adjustment of these mirror systems using our surface normal slope measuring instrument, the long trace profiler (LTP). First, we adapt a method previously used to adjust mirrors on synchrotron radiation beamlines. We measure the slope of the surface before and after a single small adjustment of each bending couple. This permits an approximation to the functional dependence of slope on the adjustments, and allows, by applying the results of a simple matrix calculation, direct adjustment to a nearly final setting. Typically, the near linearity of the problem determines a very fast convergence of the adjustment procedure. Second, we subdivide the slope data from the LTP into three regions on the mirror, and fit a circle to each sub-region by regression. This method also allows rapid iterative adjustment of both bending couples. We show that this method is a particular case of the first one. As an overall indicator of predicted performance, we ray trace, using profiler data, predicting the exact optical performance to be expected during use of the system.

A dedicated superbend x-ray microdiffraction beamline for materials, geo-, and environmental sciences at the advanced light source.

Abstract: A new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the advanced light source of the Lawrence Berkeley National Laboratory. This beamline benefits from the hard x-radiation generated by a 6 T superconducting bending magnet (superbend). This provides a hard x-ray spectrum from 5 to 22 keV and a flux within a 1 microm spot of approximately 5x10(9) photons/s (0.1% bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored by two pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick-Baez (KB) mirrors placed in a vacuum tank refocuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirror focusing. Focus spots around 1 microm are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (approximately 0.2 microm) is limited by a convolution of beam size, scan-stage resolution, and stage stability. A four-bounce monochromator consisting of two channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between white-beam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce two-dimensional maps of crystal-phases, -orientation, -texture, and -strain/stress. Typically achieved strain resolution is in the order of 5x10(-5) strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si-drift detector serves as a high-energy-resolution (approximately 150 eV full width at half maximum) fluorescence detector. Fluorescence scans can be collected in continuous scan mode with up to 300 pixels/s scan speed. A charge coupled device area detector is utilized as diffraction detector. Diffraction can be performed in reflecting or transmitting geometry. Diffraction data are processed using XMAS, an in-house written software package for Laue and monochromatic microdiffraction analysis.

Ultra-precise characterization of LCLS hard X-ray focusing mirrors by high resolution slope measuring deflectometry.

Abstract: We present recent results on the inspection of a first diffraction-limited hard X-ray Kirkpatrick-Baez (KB) mirror pair for the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). The full KB system – mirrors and holders - was under inspection by use of high resolution slope measuring deflectometry. The tests confirmed that KB mirrors of 350mm aperture length characterized by an outstanding residual figure error of <1 nm rms has been realized. This corresponds to the residual figure slope error of about 0.05µrad rms, unprecedented on such long elliptical mirrors. Additional measurements show the clamping of the mirrors to be a critical step for the final – shape preserving installation of such outstanding optics.

Sub-microradian surface slope metrology with the ALS Developmental Long Trace Profiler

Abstract: A new low-budget slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently brought to operation at the ALS Optical Metrology Laboratory. The design, instrumental control and data acquisition system, initial alignment and calibration procedures, as well as the developed experimental precautions and procedures are also described in detail. The capability of the DLTP to achieve sub-microradian surface slope metrology is verified via cross-comparison measurements with other high-performance slope measuring instruments when measuring the same high-quality test optics. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.

Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler

Abstract: Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler Valeriy V. Yashchuk, a Samuel Barber, a Edward E. Domning, a Jonathan L. Kirschman, a Gregory Y. Morrison, a Brian V. Smith, a a Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA Frank Siewert, b Thomas Zeschke, b b Helmholtz Zentrum Berlin fur Materialien und Energie, Elektronenspeicherring BESSY-II, Albert- Einstein-Str. 15, 12489 Berlin, Germany Ralf Geckeler, c Andreas Just c c Physikalische-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany 1. Introduction Development of X-ray optics for 3rd and 4th generation X-ray light sources with a level of surface slope precision of 0.1-0.2 μrad requires the development of adequate fabrication technologies and dedicated metrology instrumentation and methods. Currently, the best performance of surface slope measurement has been achieved with the NOM (Nanometer Optical Component Measuring Machine) slope profiler at BESSY (Germany) [1] and the ESAD (Extended Shear Angle Difference) profiler at the PTB (Germany) [2]. Both instruments are based on electronic autocollimators (AC) precisely calibrated for the specific application [3] with small apertures of 2.5 - 5 mm in diameter. In the present work, we describe the design, initial alignment and calibration procedures, the instrumental control and data acquisition system, as well as the measurement performance of the Developmental Long Trace Profiler (DLTP) slope measuring instrument recently brought into operation at the Advanced Light Source (ALS) Optical Metrology Laboratory (OML). Similar to the NOM and ESAD, the DLTP is based on a precisely calibrated autocollimator. However, this is a reasonably low budget instrument used at the ALS OML for the development and testing of new measuring techniques and methods. Some of the developed methods have been implemented into the ALS LTP-II (slope measuring long trace profiler [4]) which was recently upgraded and has demonstrated a capability for 0.25 µrad surface metrology [5]. Performance of the DLTP was verified via a number of measurements with high quality reference mirrors. A comparison with the corresponding results obtained with the world’s best slope measuring instrument, the BESSY NOM, proves the accuracy of the DLTP measurements on the level of 0.1-0.2 μrad depending on the curvature of a surface under test. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed. 2. DLTP Design Figure 1 illustrates the DLTP design. Figure 1: The main DLPT parts are an autocollimator “Elcomat 3000 special” (Moeller Wedel Optical [6]) calibrated at the PTB and a movable pentaprism mounted on the air-bearing carriage translated along a ceramic beam with a Nanomotion motor. The adjustable AC holder, pentaprism kinematic stage, and specially designed permanent magnet adapter for an adjustable diaphragm are used for precision alignment of the DLTP parts to ensure minimal systematic error of the slope measurement [7]. The surface under test (SUT) must be oriented face-up.