SPICA/SAFARI fourier transform spectrometer mechanism evolutionary design

TNO, together with its partners, have designed a cryogenic scanning mechanism for use in the SAFARI Fourier Transform Spectrometer (FTS) on board of the SPICA mission. SPICA is one of the M-class missions competing to be launched in ESA's Cosmic Vision Programme in 2022. JAXA leads the development of the SPICA satellite and SRON is the prime investigator of the Safari instrument. The FTS scanning mechanism (FTSM) has to meet a 35 mm stroke requirement with an Optical Path Difference resolution of less then 15 nm and must fit in a small volume. It consists of two back-to-back roof-top mirrors mounted on a small carriage, which is moved using a magnetic bearing linear guiding system in combination with a magnetic linear motor serving as the OPD actuator. The FTSM will be used at cryogenic temperatures of 4 Kelvin inducing challenging requirements on the thermal power dissipation and heat leak. The magnetic bearing enables movements over a scanning stroke of 35.5 mm in a small volume. It supports the optics in a free-floating way with no friction, or other non-linearities, with sub-nanometer accuracy. This solution is based on the design of the breadboard ODL (Optical Delay Line) developed for the ESA Darwin mission and the MABE mechanism developed by Micromega Dynamics. During the last couple of years the initial design of the SAFARI instrument, as described in an earlier SPIE 2010 paper, was adapted by the SAFARI team in an evolutionary way to meet the changing requirements of the SPICA payload module. This presentation will focus on the evolution of the FTSM to meet these changing requirements. This work is supported by the Netherlands Space Office (NSO). © 2012 SPIE

Active Damping of a Stiff Beam-like Structure with Acceleration Feedback

info:eu-repo/semantics/publishe

The development of a breadboard Cryogenic Optical Delay Line for DARWIN

TNO has developed a compact BreadBoard (BB) cryogenic Optical Delay Line (ODL) for use in future space interferometry missions such as ESA's Darwin and NASA's TPF-I. The breadboard delay line is representative of a flight mechanism. The optical design is a two-mirror cat's-eye. A linear guiding system based on magnetic bearings provides frictionless and wear free operation with zero hysteresis. The delay line has a voice coil actuator for single stage Optical Path Difference (OPD) control. The verification program, including functional testing at 40K, has been completed succesfully

The manufacturing, assembly and acceptance testing of the breadboard Cryogenic Optical Delay Line for DARWIN

TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has developed a compact breadboard cryogenic Optical Delay Line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard delay line is representative of a future flight mechanism, with all used materials and processes being flight representative. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat's eye. Magnetic bearings are used for guiding. They provide frictionless and wear free operation with zero-hysteresis. The manufacturing, assembly and acceptance testing have been completed and are reported in this paper. The verification program, including functional testing at 40 K, will start in the final quarter of 2005

Cryogenic magnetic bearing scanning mechanism design for the SPICA/SAFARI Fourier Transform Spectrometer

TNO, together with its partners Micromega and SRON, have designed a cryogenic scanning mechanism for use in the SAFARI Fourier Transform Spectrometer (FTS) on board of the SPICA mission. The optics of the FTS scanning mechanism (FTSM) consists of two back-to-back cat's-eyes. The optics are mounted on a central "back-bone" tube which houses all the important mechatronic parts: the magnetic bearing linear guiding system, a magnetic linear motor serving as the OPD actuator, internal metrology with nanometer resolution, and a launch lock. A magnetic bearing is employed to enable a large scanning stroke in a small volume. It supports the optics in a freefloating way with no friction, or other non-linearities, enabling sub-nanometer accuracy within a single stage with a stroke of -4 mm to +31.5 mm. Because the FTSM will be used at cryogenic temperatures of 4 Kelvin, the main structure and optics are all constructed from 6061 Aluminum. The overall outside dimensions of the FTSM are: 393 × 130 × 125 mm, and the mass is 2.2 kg. © 2010 SPIE

The DARWIN breadboard optical delay line verification programme

TNO, in co-operation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line (figure 1) for use in future space interferometry missions. The breadboard (BB) delay line is representative of a flight mechanism. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat's eye. Magnetic bearings provide frictionless and wear free operation with zerohysteresis. The development test programme, including operation at 100 K has been completed. The verification test programme is currently being carried out by Alcatel Alenia Space (in co-operation with Sageis-CSO) and will include functional testing at 40 K. A short design description and the intermediate results of the verification test programme are reported in this paper

Herhaling hypertensieve aandoening tijdens zwangerschap*

To assess the recurrence risk of late preterm hypertensive disease of pregnancy and to determine whether potential risk factors are predictive. Retrospective cohort study. Our study cohort included 425 women with a pregnancy-related hypertensive disorder who had delivered between 34 and 37 weeks of gestation at three different academic and three tertiary care hospitals in the Netherlands during the 2000-2002 period. Data were collected from medical files and by telephone interviews with the women. An adverse outcome was defined as the recurrence of a hypertensive disorder during the subsequent pregnancy. We also designed a prediction model containing demographic and clinical factors predictive for an adverse outcome. Of the 425 women who met the inclusion criteria, 351 could be contacted, of whom 189 (54%) had had a subsequent pregnancy. Pregnancy-related hypertensive disorders had recurred in 96 (51%; 95% CI: 43-58) women. Seventeen women (9%; 95% CI: 5-14) had delivered again before the 37th week. Pre-existing hypertension and maternal age were the strongest predictors for recurrence. Women who had experienced a recurrence had a 9-fold chance of developing chronic hypertension (37 vs. 6%; OR 8.7; 95% CI: 3.3-23). Women with hypertensive disorders and late preterm deliveries have a 50% chance of recurrence of the disorder and a 9% chance of recurrent premature delivery. Women with pre-existing hypertension or who are older are prone to recurrence. Women with a recurrent hypertensive disorder during a subsequent pregnancy often later develop chronic hypertensio