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One of the critical elements in the Four Laser Guide Star Facility (4LGSF) for the ESO Very Large Telescope (VLT) is the Optical Tube Assembly (OTA), consisting of a stable 20x laser beam expander and an active tip/tilt mirror, the Field Selector Mechanism (FSM). This paper describes the design and performance testing of the FSM. The driving requirement for the FSM is its large stroke of ±6.1 mrad, in combination with less than 1.5 µrad RMS absolute accuracy. The FSM design consists of a Zerodur mirror, bonded to a membrane spring and strut combination to allow only tip and tilt. Two spindle drives actuate the mirror, using a stiffness based transmission to increase resolution. Absolute accuracy is achieved with two differential inductive sensor pairs. A prototype of the FSM is realized to optimize the control configuration and measure its performance. Friction in the spindle drive is overcome by creating a local velocity control loop between the spindle drives and the shaft encoders. Accuracy is achieved by using a cascaded low bandwidth control loop with feedback from the inductive sensors. The pointing jitter and settling time of the FSM are measured with an autocollimator. The system performance meets the strict requirements, and is ready to be implemented in the first OTA. © 2011 SPIE.

Through the years many stable optical mounts have been designed, analyzed and tested at TNO. This paper gives an overview of the design principles used. Various examples are presented together with verification test results. The use of adhesives in combination with an iso-static mount design allows mounting of optical components in a limited volume with limited deformation of the optical surfaces due to thermal and mechanical loads. Relatively large differences in thermal expansion over large temperature ranges can be overcome using a simple and predictable design at reasonable costs. Despite adhesives have limited dimensional stability and loadability, stable optical mounts can be realized when proper design principles are used. © 2012 SPIE.

Through the years many stable optical mounts have been designed, analyzed and tested at TNO. This paper gives an overview of the design principles used. Various examples are presented together with verification test results. The use of adhesives in combination with an iso-static mount design allows mounting of optical components in a limited volume with limited deformation of the optical surfaces due to thermal and mechanical loads. Relatively large differences in thermal expansion over large temperature ranges can be overcome using a simple and predictable design at reasonable costs. Despite adhesives have limited dimensional stability and loadability, stable optical mounts can be realized when proper design principles are used. © 2012 SPIE.

Recently TNO has established EBL2; an exposure and analysis facility for testing EUV optics, reticles and pellicles under relevant EUV scanner and source conditions. The facility and EUV source complies with the ASML power roadmap of EUV systems up to a power of 500 W IF. This enables life time testing of EUV optics, reticles and pellicles under conditions which are not yet available to industry, helping the industry in preparing for HVM production. The EBL2 facility consists of a EUV source, collector optics, exposure chamber, XPS chamber, and automated sample handling. The exposure chamber has capabilities for plasma analysis, imaging ellipsometry for in-situ analysis of the sample under radiation, photodiodes for power measurements and a scintillator disk for spot profiles. It is possible to insert spectral purity filters and apertures in the beam line for wavelength tuning and beam shaping. The source is Sn fueled DPP source made by our partner Ushio and is based on the proven technology from the ASML AD-tools, providing a similar spectrum and pulse shape as used in the ASML NXE scanners. We show the results of first light obtained in December 2016. The XPS is capable of handling and analyzing full reticles and data on the obtained surface sensitivity and imaging quality will be shown.

TNO is building EBL2: a laboratory EUV exposure system capable of operating at high broad band EUV powers and intensities, in which XPS analysis of exposed samples is possible without breaking vacuum. Its goal is to accelerate the development and testing of EUV optics and components by providing a publicly accessible exposure and analysis facility. The system can accept a range of sample sizes, including standard EUV reticles with or without pellicles. In the beam line, EUV masks and other samples can be exposed to EUV radiation in a controlled environment that is representative of actual operating conditions. This contribution will describe the design of the EUV beam line.

TNO is building EBL2 as a publicly accessible test facility for EUV lithography related development of photomasks, pellicles, optics, and other components requiring EUV exposure. EBL2 consists of a EUV Beam Line, a XPS system, and sample handling infrastructure. Recently we finished installation of the source, exposure chamber, handlers and XPS system. This paper describes the integration process and first light of the EUV source. EBL2 accepts a wide range of sample sizes, including EUV masks with or without pellicles. All types of samples will be loaded using a standard dual pod interface. EUV masks returned from EBL2 will retain their NXE compatibility to facilitate wafer printing on scanners after exposure in EBL2. The Beam Line provides high intensity EUV irradiation from a Sn-fueled EUV source from Ushio. EUV intensity, spectrum, and repetition rate are all adjustable. The XPS system is now operational and accepts samples up to reticle size.