Advances in Metrology for X-Ray and EUV Optics VIII, 2019
X-ray optics, desired for beamlines at free-electron-laser and diffraction-limited-storage-ring x... more X-ray optics, desired for beamlines at free-electron-laser and diffraction-limited-storage-ring x-ray light sources, must have almost perfect surfaces, capable of delivering light to experiments without significant degradation of brightness and coherence. To accurately characterize such optics at an optical metrology lab, two basic types of surface slope profilometers are used: the long trace profilers (LTPs) and nanometer optical measuring (NOM) like angular deflectometers, based on electronic autocollimator (AC) ELCOMAT-3000. The inherent systematic errors of the instrument's optical sensors set the principle limit to their measuring performance. Where autocollimator of a NOM-like profiler may be calibrated at a unique dedicated facility, this is for a particular configuration of distance, aperture size, and angular range that does not always match the exact use in a scanning measurement with the profiler. Here we discuss the developed methodology, experimental setup , and numerical methods of transferring the calibration of one reference AC to the scanning AC of the Optical Surface Measuring System (OSMS), recently brought to operation at the ALS X˗Ray Optics Laboratory. We show that precision calibration of the OSMS performed in three steps, allows us to provide high confidence and accuracy low-spatial-frequency metrology and not 'print into' measurements the inherent systematic error of tool in use. With the examples of the OSMS measurements with a state-of-the-art x-ray aspherical mirror, available from one of the most advanced vendors of x˗ray optics, we demonstrate the high efficacy of the developed calibration procedure. The results of our work are important for obtaining high reliability data, needed for sophisticated numerical simulations of beamline performance and optimization of beamline usage of the optics.
Author(s): Kruger-Sehm, R.; Thomsen-Schmidt, P.; Yashchuk, V.; McKinney, W.R.; Takacs, P.Z.; Baku... more Author(s): Kruger-Sehm, R.; Thomsen-Schmidt, P.; Yashchuk, V.; McKinney, W.R.; Takacs, P.Z.; Bakucz, P. | Abstract: A binary pseudo random grating designed to achieve a defined power spectral density (PSD) function is investigated by interference microscopy and an angular resolving scattering light instrument. The PSD of the standard sample is designed to show white noise process characteristics in roughness evaluation and to get information about the amplitude transfer function of the measuring instrument over a defined spatial frequency range. The measured data demonstrate that both instruments influence the slope of the PSD in the wavelength range above twice as much as the grating period (Nyquist wavelength) in different ways permitting conclusions about their filtering behavior.
The autocollimator and moveable pentaprism based DLTP [NIM A 616 (2010) 212-223], a low-budget, N... more The autocollimator and moveable pentaprism based DLTP [NIM A 616 (2010) 212-223], a low-budget, NOM-like profiler at the Advanced Light Source (ALS), has been upgraded to provide fast, highly accurate surface slope metrology for long, side-facing, x-ray optics. This instrument arrangement decreases sensitivity to environmental conditions and removes the gravity effect on mirror shape. We provide design details of an affordable base tool, including clean-room environmental arrangements in the new ALS X-ray Optics Laboratory with advanced temperature stabilization and turbulence reduction, that yield measurements in under 8 hours with accuracy better than 30 nanoradians (rms) for super polished,190 mm flat optics, limited mainly by residual temporal instability of the experimental set-up. The upgraded DLTP has been calibrated for highly curved x-ray optics, allowing same day measurements of a 15 m ROC sphere with accuracy of better than 100 nanoradians (rms). The developed calibration procedure is discussed in detail. We propose this specific 15 m ROC sphere for use as a round-robin calibration test optic.
Verification of the reliability of metrology data from high quality x-ray optics requires adequat... more Verification of the reliability of metrology data from high quality x-ray optics requires adequate methods for test and calibration of the instruments be developed. For such verification of optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1-3] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [4].
An open-source database containing metrology data for X-ray mirrors is presented. It makes availa... more An open-source database containing metrology data for X-ray mirrors is presented. It makes available metrology data (mirror heights and slopes profiles) that can be used with simulation tools for calculating the effects of optical surface errors in the performances of an optical instrument, such as a synchrotron beamline. A typical case is the degradation of the intensity profile at the focal position in a beamline due to mirror surface errors. This database for metrology (DABAM) aims to provide to the users of simulation tools the data of real mirrors. The data included in the database are described in this paper, with details of how the mirror parameters are stored. An accompanying software is provided to allow simple access and processing of these data, calculate the most usual statistical parameters, and also include the option of creating input files for most used simulation codes. Some optics simulations are presented and discussed to illustrate the real use of the profiles fr...
Advances in X-Ray/EUV Optics and Components III, 2008
State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIX... more State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIXS) require diffraction gratings which can provide extremely high spectral resolution of 10 5-10 6. This problem may be addressed with a sliced multilayer grating with an ultra-high groove density (up to 50,000 mm-1) proposed in the recent publication [Voronov,
Realizing the experimental potential of high-brightness, next generation synchrotron and free-ele... more Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, atwavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing. The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. Visible-light long-trace profilometry was used to pre-align the mirror before installation at the beamline. This work demonstrates that high-accuracy, at-wavelength wavefrontslope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.
Advances in Metrology for X-Ray and EUV Optics VIII, 2019
We investigate and compare the spatial (lateral) resolution, or more generally, the optical/instr... more We investigate and compare the spatial (lateral) resolution, or more generally, the optical/instrumental transfer function (OTF/ITF) of surface slope measuring profilometers of two different types that are commonly used for high accuracy characterization of x-ray optics at the long-spatial-wavelength range. These are an autocollimator based profiler, Optical Surface Measuring System (OSMS), and a long trace profiler, LTP-II, both available at the Advanced Light Source (ALS) X˗Ray Optics Lab (XROL). In the OSMS, an ELCOMAT-3000 electronic auto-collimator, vertically mounted to the translation carriage and equipped with an aperture of 2.5 mm diameter, is scanned along the surface under test. The LTP˗II OTF has been measured for two different configurations, a classical two-beam pencil-beam-interferometry and a single-Gaussian-beam deflectometry. For the ITF calibration, we apply a recently developed method based on test surfaces with one-dimensional (1D) linear chirped height profiles of constant slope amplitude. Analytical expressions for the OTFs, empirically deduced based on the experimental results, are presented. We also discuss the application of the results of the ITF measurements and modeling to improve the surface slope metrology with state-of-the-art x-ray mirrors. This work was supported by the U. S. Department of Energy under contract number DE-AC02-05CH11231.
NATO Science Series II: Mathematics, Physics and Chemistry
ABSTRACT Resonant enhancement of optical Kerr and higher order nonlinearities in multilevel syste... more ABSTRACT Resonant enhancement of optical Kerr and higher order nonlinearities in multilevel systems under the conditions of electromagnetically-induced transparency might be useful for quantum signal processing. The main problem with these schemes is related to the selective measurement of high-order atomic coherences that requires multiphoton interactions for the production and detection. In this paper we present a method in which a single laser beam is used for the creation of required nonlinear interactions. It is based on the nonlinear magneto-optical rotation with frequency-modulated light. Using this technique, we measure the nonlinear Faraday rotation caused by four-photon atomic coherence in M-type system. The method is also applicable to the selective control of higher order atomic coherences.
We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) o... more We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) on the sensitivity of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of N atomic spins by detecting optical rotation of far-detuned light. We show that for very short measurement times, the optimal sensitivity scales as N ÿ3=4 ; if strongly squeezed probe light is used, the Heisenberg limit of N ÿ1 scaling can be achieved. However, if the measurement time exceeds rel =N 1=2 in the former case, or rel =N in the latter, where rel is the spin relaxation time, the scaling becomes N ÿ1=2 , as for a standard shot-noise-limited magnetometer.
Nonlinear magneto-optical Faraday rotation (NMOR) on the potassium D1 and D2 lines was used to st... more Nonlinear magneto-optical Faraday rotation (NMOR) on the potassium D1 and D2 lines was used to study Zeeman relaxation rates in an antirelaxation paraffin-coated 3-cm diameter potassium vapor cell. Intrinsic Zeeman relaxation rates of γ N M OR /2π = 2.0(6) Hz were observed. The relatively small hyperfine intervals in potassium lead to significant differences in NMOR in potassium compared to rubidium and cesium. Using laser optical pumping, widths and frequency shifts were also determined for transitions between ground-state hyperfine sublevels of 39 K atoms contained in the same paraffincoated cell. The intrinsic hyperfine relaxation rate of γ hf expt /2π = 10.6(7) Hz and a shift of −9.1(2) Hz were observed. These results show that adiabatic relaxation gives only a small contribution to the overall hyperfine relaxation in the case of potassium, and the relaxation is dominated by other mechanisms similar to those observed in previous studies with rubidium.
A low-light-power theory of nonlinear magneto-optical rotation of frequency-modulated light reson... more A low-light-power theory of nonlinear magneto-optical rotation of frequency-modulated light resonant with a J = 1 → J ′ = 0 transition is presented. The theory is developed for a Doppler-free transition, and then modified to account for Doppler broadening and velocity mixing due to collisions. The results of the theory are shown to be in qualitative agreement with experimental data obtained for the rubidium D1 line.
Systematic error and instrumental drift are the major limiting factors of sub-microradian slope m... more Systematic error and instrumental drift are the major limiting factors of sub-microradian slope metrology with state-ofthe-art x-ray optics. Significant suppression of the errors can be achieved by using an optimal measurement strategy suggested in [Rev. Sci. Instrum. 80, 115101 (2009)]. Here, we report on development of an automated, kinematic, rotational system that provides fully controlled flipping, tilting, and shifting of a surface under test. The system is to be integrated into the Advanced Light Source long trace profiler, LTP-II, allowing for complete realization of the advantages of the optimal measurement strategy method. We describe in detail the system"s specification, design operational control and data acquisition. The performance of the system is demonstrated via the results of high precision measurements with a number of super-polished mirrors.
We describe a revolutionary new approach to high spectral resolution soft x-ray optics. Conventio... more We describe a revolutionary new approach to high spectral resolution soft x-ray optics. Conventionally in the soft x-ray energy range, high spectral resolution is obtained by use of a relatively low line density grating operated in 1 st order with small slits. This severely limits throughput. This limitation can be removed by use of a grating either in very high order, or with very high line density, if one can maintain high diffraction efficiency. We have developed a new technology for achieving both of these goals which should allow high throughput spectroscopy, at resolving powers of up to 10 6 at 1 keV. Such optics should provide a revolutionary advance for high resolution lifetime free spectroscopy, such as RIXS, and for pulse compression of chirped beams. We report recent developmental fabrication and characterization of a prototype grating optimized for 14.2 nm EUV light. The prototype grating with a 200 nm period of the blazed grating substrate coated with 20 Mo/Si bilayers with a period of 7.1 nm demonstrates good dispersion in the third order (effective groove density of 15,000 lines per mm) with a diffraction efficiency of more than 33%.
The X-Ray Optics Laboratory (XROL) at the Advanced Light Source (ALS), a unique optical metrology... more The X-Ray Optics Laboratory (XROL) at the Advanced Light Source (ALS), a unique optical metrology lab, has been recently moved to a new, dedicated clean-room facility that provides improved environmental and instrumental conditions vitally required for high accuracy metrology with state-of-the-art X-ray optics. Besides the ALS, the XROL serves several DOE labs that lack dedicated on-site optical metrology capabilities, including the Linac Coherent Light Source (LCLS) at SLAC and LBNL’s Center for X-Ray Optics (CXRO). The major role of XROL is to proactively support the development and optimal beamline use of x-ray optics. The application of different instruments available in the lab enables separate, often complementary, investigations and addresses of different potential sources of error affecting beamline performance. At the beamline, all the perturbations combine to produce a cumulative effect on the performance of the optic that makes it difficult to optimize the optic's operational performance. Ex situ metrology allows us to address the majority of the problems before the installation of the optic at a beamline, and to provide feedback on design and guidelines for the best usage of optics. We will review the ALS XROL mission, lab design and arrangement, ex situ metrology capabilities and performance, as well as the future plans for instrumentation upgrades. The discussion will be illustrated with the results of a broad spectrum of measurements of x-ray optics and optical systems performed at the XROL.
A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with... more A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with active participation of the HBZ-BESSY-II optics group has been established to work together on a new slope measuring profiler-the optical slope measuring system (OSMS). The slope measurement accuracy of the instrument is expected to be <50 nrad for the current and future metrology of x-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable; and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).
Advances in Metrology for X-Ray and EUV Optics VIII, 2019
X-ray optics, desired for beamlines at free-electron-laser and diffraction-limited-storage-ring x... more X-ray optics, desired for beamlines at free-electron-laser and diffraction-limited-storage-ring x-ray light sources, must have almost perfect surfaces, capable of delivering light to experiments without significant degradation of brightness and coherence. To accurately characterize such optics at an optical metrology lab, two basic types of surface slope profilometers are used: the long trace profilers (LTPs) and nanometer optical measuring (NOM) like angular deflectometers, based on electronic autocollimator (AC) ELCOMAT-3000. The inherent systematic errors of the instrument's optical sensors set the principle limit to their measuring performance. Where autocollimator of a NOM-like profiler may be calibrated at a unique dedicated facility, this is for a particular configuration of distance, aperture size, and angular range that does not always match the exact use in a scanning measurement with the profiler. Here we discuss the developed methodology, experimental setup , and numerical methods of transferring the calibration of one reference AC to the scanning AC of the Optical Surface Measuring System (OSMS), recently brought to operation at the ALS X˗Ray Optics Laboratory. We show that precision calibration of the OSMS performed in three steps, allows us to provide high confidence and accuracy low-spatial-frequency metrology and not 'print into' measurements the inherent systematic error of tool in use. With the examples of the OSMS measurements with a state-of-the-art x-ray aspherical mirror, available from one of the most advanced vendors of x˗ray optics, we demonstrate the high efficacy of the developed calibration procedure. The results of our work are important for obtaining high reliability data, needed for sophisticated numerical simulations of beamline performance and optimization of beamline usage of the optics.
Author(s): Kruger-Sehm, R.; Thomsen-Schmidt, P.; Yashchuk, V.; McKinney, W.R.; Takacs, P.Z.; Baku... more Author(s): Kruger-Sehm, R.; Thomsen-Schmidt, P.; Yashchuk, V.; McKinney, W.R.; Takacs, P.Z.; Bakucz, P. | Abstract: A binary pseudo random grating designed to achieve a defined power spectral density (PSD) function is investigated by interference microscopy and an angular resolving scattering light instrument. The PSD of the standard sample is designed to show white noise process characteristics in roughness evaluation and to get information about the amplitude transfer function of the measuring instrument over a defined spatial frequency range. The measured data demonstrate that both instruments influence the slope of the PSD in the wavelength range above twice as much as the grating period (Nyquist wavelength) in different ways permitting conclusions about their filtering behavior.
The autocollimator and moveable pentaprism based DLTP [NIM A 616 (2010) 212-223], a low-budget, N... more The autocollimator and moveable pentaprism based DLTP [NIM A 616 (2010) 212-223], a low-budget, NOM-like profiler at the Advanced Light Source (ALS), has been upgraded to provide fast, highly accurate surface slope metrology for long, side-facing, x-ray optics. This instrument arrangement decreases sensitivity to environmental conditions and removes the gravity effect on mirror shape. We provide design details of an affordable base tool, including clean-room environmental arrangements in the new ALS X-ray Optics Laboratory with advanced temperature stabilization and turbulence reduction, that yield measurements in under 8 hours with accuracy better than 30 nanoradians (rms) for super polished,190 mm flat optics, limited mainly by residual temporal instability of the experimental set-up. The upgraded DLTP has been calibrated for highly curved x-ray optics, allowing same day measurements of a 15 m ROC sphere with accuracy of better than 100 nanoradians (rms). The developed calibration procedure is discussed in detail. We propose this specific 15 m ROC sphere for use as a round-robin calibration test optic.
Verification of the reliability of metrology data from high quality x-ray optics requires adequat... more Verification of the reliability of metrology data from high quality x-ray optics requires adequate methods for test and calibration of the instruments be developed. For such verification of optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1-3] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [4].
An open-source database containing metrology data for X-ray mirrors is presented. It makes availa... more An open-source database containing metrology data for X-ray mirrors is presented. It makes available metrology data (mirror heights and slopes profiles) that can be used with simulation tools for calculating the effects of optical surface errors in the performances of an optical instrument, such as a synchrotron beamline. A typical case is the degradation of the intensity profile at the focal position in a beamline due to mirror surface errors. This database for metrology (DABAM) aims to provide to the users of simulation tools the data of real mirrors. The data included in the database are described in this paper, with details of how the mirror parameters are stored. An accompanying software is provided to allow simple access and processing of these data, calculate the most usual statistical parameters, and also include the option of creating input files for most used simulation codes. Some optics simulations are presented and discussed to illustrate the real use of the profiles fr...
Advances in X-Ray/EUV Optics and Components III, 2008
State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIX... more State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIXS) require diffraction gratings which can provide extremely high spectral resolution of 10 5-10 6. This problem may be addressed with a sliced multilayer grating with an ultra-high groove density (up to 50,000 mm-1) proposed in the recent publication [Voronov,
Realizing the experimental potential of high-brightness, next generation synchrotron and free-ele... more Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, atwavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing. The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. Visible-light long-trace profilometry was used to pre-align the mirror before installation at the beamline. This work demonstrates that high-accuracy, at-wavelength wavefrontslope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.
Advances in Metrology for X-Ray and EUV Optics VIII, 2019
We investigate and compare the spatial (lateral) resolution, or more generally, the optical/instr... more We investigate and compare the spatial (lateral) resolution, or more generally, the optical/instrumental transfer function (OTF/ITF) of surface slope measuring profilometers of two different types that are commonly used for high accuracy characterization of x-ray optics at the long-spatial-wavelength range. These are an autocollimator based profiler, Optical Surface Measuring System (OSMS), and a long trace profiler, LTP-II, both available at the Advanced Light Source (ALS) X˗Ray Optics Lab (XROL). In the OSMS, an ELCOMAT-3000 electronic auto-collimator, vertically mounted to the translation carriage and equipped with an aperture of 2.5 mm diameter, is scanned along the surface under test. The LTP˗II OTF has been measured for two different configurations, a classical two-beam pencil-beam-interferometry and a single-Gaussian-beam deflectometry. For the ITF calibration, we apply a recently developed method based on test surfaces with one-dimensional (1D) linear chirped height profiles of constant slope amplitude. Analytical expressions for the OTFs, empirically deduced based on the experimental results, are presented. We also discuss the application of the results of the ITF measurements and modeling to improve the surface slope metrology with state-of-the-art x-ray mirrors. This work was supported by the U. S. Department of Energy under contract number DE-AC02-05CH11231.
NATO Science Series II: Mathematics, Physics and Chemistry
ABSTRACT Resonant enhancement of optical Kerr and higher order nonlinearities in multilevel syste... more ABSTRACT Resonant enhancement of optical Kerr and higher order nonlinearities in multilevel systems under the conditions of electromagnetically-induced transparency might be useful for quantum signal processing. The main problem with these schemes is related to the selective measurement of high-order atomic coherences that requires multiphoton interactions for the production and detection. In this paper we present a method in which a single laser beam is used for the creation of required nonlinear interactions. It is based on the nonlinear magneto-optical rotation with frequency-modulated light. Using this technique, we measure the nonlinear Faraday rotation caused by four-photon atomic coherence in M-type system. The method is also applicable to the selective control of higher order atomic coherences.
We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) o... more We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) on the sensitivity of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of N atomic spins by detecting optical rotation of far-detuned light. We show that for very short measurement times, the optimal sensitivity scales as N ÿ3=4 ; if strongly squeezed probe light is used, the Heisenberg limit of N ÿ1 scaling can be achieved. However, if the measurement time exceeds rel =N 1=2 in the former case, or rel =N in the latter, where rel is the spin relaxation time, the scaling becomes N ÿ1=2 , as for a standard shot-noise-limited magnetometer.
Nonlinear magneto-optical Faraday rotation (NMOR) on the potassium D1 and D2 lines was used to st... more Nonlinear magneto-optical Faraday rotation (NMOR) on the potassium D1 and D2 lines was used to study Zeeman relaxation rates in an antirelaxation paraffin-coated 3-cm diameter potassium vapor cell. Intrinsic Zeeman relaxation rates of γ N M OR /2π = 2.0(6) Hz were observed. The relatively small hyperfine intervals in potassium lead to significant differences in NMOR in potassium compared to rubidium and cesium. Using laser optical pumping, widths and frequency shifts were also determined for transitions between ground-state hyperfine sublevels of 39 K atoms contained in the same paraffincoated cell. The intrinsic hyperfine relaxation rate of γ hf expt /2π = 10.6(7) Hz and a shift of −9.1(2) Hz were observed. These results show that adiabatic relaxation gives only a small contribution to the overall hyperfine relaxation in the case of potassium, and the relaxation is dominated by other mechanisms similar to those observed in previous studies with rubidium.
A low-light-power theory of nonlinear magneto-optical rotation of frequency-modulated light reson... more A low-light-power theory of nonlinear magneto-optical rotation of frequency-modulated light resonant with a J = 1 → J ′ = 0 transition is presented. The theory is developed for a Doppler-free transition, and then modified to account for Doppler broadening and velocity mixing due to collisions. The results of the theory are shown to be in qualitative agreement with experimental data obtained for the rubidium D1 line.
Systematic error and instrumental drift are the major limiting factors of sub-microradian slope m... more Systematic error and instrumental drift are the major limiting factors of sub-microradian slope metrology with state-ofthe-art x-ray optics. Significant suppression of the errors can be achieved by using an optimal measurement strategy suggested in [Rev. Sci. Instrum. 80, 115101 (2009)]. Here, we report on development of an automated, kinematic, rotational system that provides fully controlled flipping, tilting, and shifting of a surface under test. The system is to be integrated into the Advanced Light Source long trace profiler, LTP-II, allowing for complete realization of the advantages of the optimal measurement strategy method. We describe in detail the system"s specification, design operational control and data acquisition. The performance of the system is demonstrated via the results of high precision measurements with a number of super-polished mirrors.
We describe a revolutionary new approach to high spectral resolution soft x-ray optics. Conventio... more We describe a revolutionary new approach to high spectral resolution soft x-ray optics. Conventionally in the soft x-ray energy range, high spectral resolution is obtained by use of a relatively low line density grating operated in 1 st order with small slits. This severely limits throughput. This limitation can be removed by use of a grating either in very high order, or with very high line density, if one can maintain high diffraction efficiency. We have developed a new technology for achieving both of these goals which should allow high throughput spectroscopy, at resolving powers of up to 10 6 at 1 keV. Such optics should provide a revolutionary advance for high resolution lifetime free spectroscopy, such as RIXS, and for pulse compression of chirped beams. We report recent developmental fabrication and characterization of a prototype grating optimized for 14.2 nm EUV light. The prototype grating with a 200 nm period of the blazed grating substrate coated with 20 Mo/Si bilayers with a period of 7.1 nm demonstrates good dispersion in the third order (effective groove density of 15,000 lines per mm) with a diffraction efficiency of more than 33%.
The X-Ray Optics Laboratory (XROL) at the Advanced Light Source (ALS), a unique optical metrology... more The X-Ray Optics Laboratory (XROL) at the Advanced Light Source (ALS), a unique optical metrology lab, has been recently moved to a new, dedicated clean-room facility that provides improved environmental and instrumental conditions vitally required for high accuracy metrology with state-of-the-art X-ray optics. Besides the ALS, the XROL serves several DOE labs that lack dedicated on-site optical metrology capabilities, including the Linac Coherent Light Source (LCLS) at SLAC and LBNL’s Center for X-Ray Optics (CXRO). The major role of XROL is to proactively support the development and optimal beamline use of x-ray optics. The application of different instruments available in the lab enables separate, often complementary, investigations and addresses of different potential sources of error affecting beamline performance. At the beamline, all the perturbations combine to produce a cumulative effect on the performance of the optic that makes it difficult to optimize the optic's operational performance. Ex situ metrology allows us to address the majority of the problems before the installation of the optic at a beamline, and to provide feedback on design and guidelines for the best usage of optics. We will review the ALS XROL mission, lab design and arrangement, ex situ metrology capabilities and performance, as well as the future plans for instrumentation upgrades. The discussion will be illustrated with the results of a broad spectrum of measurements of x-ray optics and optical systems performed at the XROL.
A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with... more A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with active participation of the HBZ-BESSY-II optics group has been established to work together on a new slope measuring profiler-the optical slope measuring system (OSMS). The slope measurement accuracy of the instrument is expected to be <50 nrad for the current and future metrology of x-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable; and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).
Uploads
Papers by V. Yashchuk