The micro-tomography endstation at Taiwan Photon Source (TPS) utilizes an efficient design that incorporates a high-flux source, automated pre-alignment, automated sample loading/unloading and a sample storage system resulting in highly efficient operation. In double crystal monochromator (DCM) mode, the sample can be scanned in full resolution within 2 minutes which Includes loading sample, positioning, scan, and unloading sample, with up to 880 samples continuously scanned in the queue. This endstation was opened to user at 2022. This presentation will also cover the new nano-CT endstation which will be ready in 2024.
The small radius x-ray mirror in the interferometer stitching measurement is needed high angle resolution rotation stage to get reliable angle information. The rotation stage rotary range requirement is not wide, because of the X-ray mirror radius generally large than 200M, and the mirror length small than 1.2M. The angle resolution is needed high resolution, therefore, in interferometer stitching measurement, the interferogram is easily affected by the rotation angle difference. Thus, this study is to design a small angle traveling range (rotation angle maximum ± 1.5 degrees), high angle resolution (10 nrad.), and high loading capacity (loading maximum 75 Kg) rotation stage, the rotation mechanism is applied pivot bearing to get high-resolution rotation angle. The rotation stage design is finished, this article discusses system assembly and test.
Long trace profiler (LTP) is used to measure the large radius mirror surface profile. The in-situ LTP can be used to measure the X-ray mirror of an adaptive mirror bending system inside the vacuum chamber. In this study, the in-situ LTP measure head is outside of vacuum chamber. Therefore, the vacuum chamber and window glass thermal effect can introduce errors into the measurement results. This study calculated temperature distribution and deformation using the finite element method (FEM) software and calculate incident ray through the window glass. The incident ray through window glass with thermal gradient could increase optical path difference (OPD). The calculation resulted in an evaluation of in-situ LTP measurement error by thermal deformation.
The project of transmission x-ray microscope (TXM) with tender x-ray is undergoing as an extension project of the soft x-ray tomography (SXT) endstation at Taiwan Photon Source (TPS). This TXM is aimed for energy from 1.5 keV to 2.4 keV and with phase contrast with the x-ray energy of 2.4 keV. As the extension of current SXT project, the beamline will be equipped with a variable line spacing (VLS) grating with the multi-layer coating which will be optimized for 2.4 keV.
This TXM will be zoneplate based with a phase ring and capillary condenser. In order to match the field of view and numerical aperture (NA) of zoneplate with the emittance of the source in vertical direction, some compromise should be made. To match the low emittance of vertical direction, the NA of zoneplate should be lower and vertical of the secondary source should be larger. This will lower spatial resolution and energy resolution. The targeting resolution of this TXM for phase contrast will be 50nm and FOV is 20 μm. For the detector, which is currently design with a scintillator with a CCD detector. For the future, the direct detector for small pixel and high signal to noise ratio can be obtained. The other components of TXM, such as stages, cryo system, which can be shared with current SXT system which works under the energy of the water window region.
This endstation for tender X-ray will be commission in 2020. The detailed design and current progress will be discussed in this presentation.
The PXM (Projection X-ray Microscope) end station was used to complete a preliminary test at the SPring-8 12B2 beamline. The x-ray through scintillator and knife-edge become visible-light image can get from the sensor. The knifeedge image has an edge shape, which can create the edge response line. The edge response line can be differentiated from the point response line. The point response line can then be transferred by Fourier transformation, and achieve MTF (Modulation Transfer Function). Here we apply Chebyshev polynomials to fit the edge response line and calculate the MTF. We used 20× and 50× objective lenses to generate the knife-edge images and calculate the MTF value. We found that the scintillator design resolution is 1 μm, and following the MTF calculation, the image resolutions are about 3 μm and 1.4 μm in the 20× and 50× objective lens, respectively.
The goal of an in situ Long Trace Profiler (LTP) is to adjust the mirror to 0.1 μrad Root Mean Square (RMS) under thermal load. Here we introduce the measurement configuration for in situ LTP. To avoid lens aberration, the moving optical head keeps the optical paths constant, and the reference beam is used to the correct of the unavoidable air bearing errors. The window glass in this test has a rather high optical quality, with a flatness of 1/150 (RMS) over 120 × 20 mm. The optical quality of the window was specified to be ± 1 μrad slope distortion in an aperture length of 100 mm. The window glass deformation for the air pressure was calculated by the Finite Element Method (FEM) software (ANSYS). The window glass deformation results can be fitting by the Zernike polynomial, and then bring it into the sequential optical ray tracing software (ZEMAX), and evaluating the window glass effect on the LTP measurement results. By this approach, we found that this has a constant error. Thus, the window glass air pressure error can be effectively removed from the measurement result to reveal the real mirror profile. Using the in situ LTP measuring result and the data iteration process, the bendable mirror can control the optical surface locate profile and thereby minimize the thermal distort effect. The slope error will be reduced to 0.1 μrad at the thermal load.
The project “High loading precision rotation stage design for synchrotron radiation mirror measurement” aims to provide an ultra-high-precision heavy-duty rotation stage and X-ray mirror interference optical measurements. Since the shape of an X-ray lens is very different from that of the general visible optical lens, the measurement system is very different from the general visible light optical measurement system. This paper describes a high-load precision rotating platform for obtaining stitching interferometer measurements for a synchrotron radiation mirror. The synchrotron radiation mirror is usually rectangular, and the length is greater than the interferometer measurement size. Therefore, for the mirror measurement, the stitching method is usually used to obtain synchrotron radiation mirror measurements. The interference measurements are obtained at different positions. In order to obtain the measurements, the center line of the interferometer must be perpendicular to the tangent of the mirror surface, so that appropriate interference fringes can be obtained. As the mirror radius becomes smaller, the interferometer rotation angle sensitivity increases. Development of the stitching interferometer high-load precision rotating platform design target requires an angle rotation resolution <10 nrad, considering the weight of the general interferometer plus the reference lens, related accessories, and safety factors is about 50 kg so that the rotating platform design load is 70 kg.
The thermal transfer issue is an important problem associated with the synchrotron radiation optical system. During projection x-ray microscopy (PXM), x-ray light comes from the wiggler insert parts. The vertical collimating mirror (VCM) absorbs 40 W of energy on the mirror surface. The mirror length is 1000 mm, and its width is 87 mm. Here we apply an x-ray optical simulation software, named SHADOW, as well as the finite element method (FEM) software, ANSYS®, to calculate the surface thermal deformation at various thicknesses of VCM. The FEM software calculates the mirror surface deformation from heat absorption, and the surface deformation can be fit by the B-spline curve. The thermal deformation fitting results can be fed back to the SHADOW software and be used to evaluate how mirror thermal deformation affects the optical system performance.
This on-the-fly scanning control system is for the x-ray nanoprobe endstation at Taiwan Photon Source(TPS) and built base-on the high speed Hardware (H/W), high throughput data stream and multi-channel control interfaces. The main idea is to tag each data with information of time and position, which generates by circuit and laser interferometer. The data is then processed by a computer to be analyzed and visualized.
By using high speed FPGA with embedded processer to process the input and output data which includes the DAC, ADC, Gigabit Ethernet (GbE), X-ray fluorescence (XRF) and laser interferometer control interfaces. Three DAC control the X,Y and Z axes of the flexure stage, four ADCs and sensor interfaces gather the data and packet it into data packet. GbE send data back to computer to do image processing then reconstruct the scanning image. The numerous data not only for rebuild the image but also good for information analysis. Including the vibration, time slide analysis.
Our demo system is built by an e-beam source, flexure stage and laser interferometer. The current maximum scanning speed is up to 5 lines/sec which is limited by the mechanical, the sample rate can be as high as 20M samples/sec which limited by laser interferometer, and the maximum data rate is close to 100M bytes/sec which is limited by the GbE. Interferometer information combine with position data in data packet, makes easy for data analysis and also for image stitching. The system is going to commission on beamline at March, 2017. The commission result for this system will be presented.
The diffraction-limited Montel mirrors, equipped at the X-ray Nanoprobe (XNP) at Taiwan Photon Source (TPS), provide a 40 nm focal spot and working distance 55 mm under the total beamline length of 69 m. The underneath holder supporting for the Montel mirrors is a 12 axes flexure based manipulators in which 10 out of the 12 axes are motorized. To monitor the position and stability of individual holder motion, a monitoring system consisted of three optical encoders and three- axes laser interferometers for angle movement is implemented. The gap width between the two mirrors and their orthogonality can be adjusted by a tilting sensor and a high magnification optical microscope. The focusing properties, phase and amplitude, after the Montel mirrors will be investigated by means of coherent Ptychography, as well as by zone plate imaging. An SEM in close cooperation with laser interferometers is equipped to precisely position the samples and conduct the on-the-fly scan. A high speed FPGA based circuit is developed to address signal from XRF, XAS, XEOL and XRD. Data is in tag with position and time information and been processed by computers to allow 5nm precision stage scanning free from mechanical feedback. The XNP at TPS is under commissioning since February 2017. The commissioning result, particularly the performance of the Montel mirrors will be reported in this presentation.
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