In Taiwan photon source facilities, soft x-ray beamlines are equipped with self-developed active high-precision mirrors or gratings. It is crucial to establish more advanced optical surface metrology instruments to satisfy the demands of optical production, installation, and testing in synchrotron optics. A long trace profiler (LTP) is an instrument used to measure the optical surface’s slope. This assists in monitoring the installation processes of optical instruments to ensure that the final optical components satisfy the required specifications in terms of quality. In this study, we propose a new air-bearing slide design to achieve nanometer-level precision for the LTP. This new design replaces ceramic and granite structures and addresses rail deformation and surface imperfections. This LTP features a specially designed bendable linear slide comprising four airbrushes, two shafts, and eight end mounts. The motion stage, supported and guided by four airbrushes against two parallel steel shafts, carries the optical head. End mounts are installed on the tilting stage at both ends, using flexure guides with manually adjusted screws and fine-tuning piezo. The rail system can be bent to a third-order polynomial rail profile to compensate for the effect of gravity when moving the optical head, enabling the achievement of the desired rail pitch variation within a distance of 400 mm with 2.5 μrad (RMS). To further enhance the precision, dynamic correction methods can be employed by utilizing PZT actuators and bender mechanisms. These mechanisms enabled rail pitch variation as low as 0.2 μrad (RMS).We introduce a new design for an air-bearing slide and its corresponding performance. This slide design is employed in LTP measurements. The outcomes of our study demonstrate a correlation between the observed results and the rail pitch profile.
To achieve an ultrahigh-resolution for soft X-ray beamlines, the slope error of a highly precise grating is required on the level of 0.1 μrad root-mean-square (RMS) under thermal loading. To realize the goal, a specially designed 25-actuator optical surface bender for the gratings and mirrors is developed and operated at Taiwan Photon Source (TPS) [1]. In this paper, the construction and operation of the in situ LTP measuring system is described[2]. This LTP consists of a switchable optical reflection system that let the LTP can switch to measure horizontal or vertical mounting mirrors/gratings in the beamline. The other is a low optical distortion and bakeable to 120 ˚C glass viewport which is used for the ultra-high vacuum[3,4] interface for the beamlines optics and LTP. The surface slope error being reduced down to 0.1 and 0.15 μrad (RMS) by the 25-actuator bender without/with the glass viewport as verified by the in situ LTP measurements in the beamline.
To achieve an ultrahigh resolution for soft X-ray beamlines at Taiwan Photon Source (TPS), the slope error of a highly precise grating is required on level of 0.1 μrad (rms) under thermal loading with various curvatures. On the beamline, some optics are usually operating under high power density from undulator magnet, the thermal load will introduce a thermal bump on the optics profile and degrade the beamline performance, such as energy resolution and beam size.
To realize the high resolution goal, a specially designed bender with 25 actuators for the grating is designed and a In situ long trace profiler (LTP) with precision of 0.1 μrad (rms) has been developed to measure the mirror profile in soft X-ray beamlines.
This article introduces the design and construction of in situ LTP. It can provide a feedback guideance for the adjustment of actuators of bender mechanism to achieve the optium profile. A suitable adjustment procedure from the input of in-situ LTP , performance of bender and energy spectrums are presented.
There are several benders as the active mirrors and active gratings in operation in TPS 41A resonant inelastic X-ray scattering (RIXS) and TPS 45A angle-resolved photoemission spectroscopy (ARPES) beamlines. In the meantime, three in situ LTPs have been developed to monitor the grating profile under the thermal load in the beamlines. They are providing a feedback to measure the surface figure and to find the optimal surface profile. They would increase our efficiency to reach the energy resolving power of 35,000 and 28,000 in the RIXS and ARPES beamlines, respectively.
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