Selected technologies for the integration of the TRANSMIT/RECEIVE OPTICS (TRO) are presented. One of the challenging characteristics of the TRO is its stringent requirement on opto-mechanical stability. The stability performance of the TRO must be ensured for the relevant interface environments (thermal, structural) over the 3 years mission lifetime. Comprehensive analyses have been conducted, which have confirmed the need for the development of special integration technologies. Also, dedicated test equipment has been developed to precisely verify the TRO´s optomechanical stability. Another important feature of the TRO is its exposure to the high power laser beam of the ADALIN instrument. The corresponding optical elements and their mounts must survive exposure to light intensities up to the required laser-induced damage thresholds (LIDT). Two types of adhesives for gluing of the TRO optics have been selected. Their qualification w.r.t. outgassing was necessary since LIDT´s of optical surfaces are significantly reduced when organic outgassing products are deposited there.
This paper presents the mission profile as well as the optical configuration of the space-borne AsteroidFinder telescope. Its main objective is to retrieve asteroids with orbits interior to the earth’s orbit. The instrument requires high sensitivity to detect asteroids with a limiting magnitude of equal or larger than 18.5mag (V-Band) and astrometric accuracy of 1arcsec (1σ). This requires a telescope aperture greater than 400cm2, high image stability, detector with high quantum efficiency (peak > 90%) and very low noise, which is only limited by zodiacal background. The telescope will observe the sky between 30° and 60° in solar elongation. The telescope optics is based on a Cook type TMA. An effective 2°×2° field of view (FOV) is achieved by a fast F/3.4 telescope with near diffraction-limited performance. The absence of centre obscuration or spiders in combination with an accessible intermediate field plane and exit pupil allow for efficient stray light mitigation. Design drivers for the telescope are the required point spread function (PSF) values, an extremely efficient stray light suppression (due to the magnitude requirement mentioned above), the detector performance, and the overall optical and mechanical stability for all orientations of the satellite. To accommodate the passive thermal stabilization scheme and the necessary structural stability, the materials selection for the telescope main structure and the mirrors are of vital importance. A focal plane with four EMCCD detectors is envisaged. The EMCCD technology features shorter integration times, which is in favor regarding the pointing performance of the satellite. The launch of the mission is foreseen for the year 2013 with a subsequent mission lifetime of at least 1 year.
This paper presents the design and key technologies of the Transmit-Receive Optics (TRO) for the Aladin lidar instrument. The TRO as the central optical interface on the Aladin instrument leading the optical signals from the laser source to the emitting/receiving telescope, and vice versa, the received back scattered signals from the telescope to the spectrometers for Doppler shift evaluation. Additionally, the TRO contains a calibration branch bypassing the telescope and aims at levelling out the received signals in terms of wavelength and signal height changes due to wavelength and
intensity variations of the laser. The opto-mechanical concept of the TRO consists of afocal optical groups, which are connected by parallel beams. Extreme requirements have been defined for the TRO on the end-to-end transmission (>=73 %) with an associated effective bandwidth of less than 1 nm over the 200 - 1100 nm spectral range. The achieved solution is presented in this paper. A further feature of the TRO is the use of two so-called aberration generators on the
emitting and calibration branch, with which an artificial astigmatism can be realised for eye safety reasons. Its effect on astigmatism is presented. This article also addresses the effort on stray light suppression, which is of extreme importance for the TRO. Special ion plated (IP) optical coatings have been used with superior performance for the TRO, particulary on laser energy resistance and air/vacuum stability. The development of special mounting technologies of optical elements to meet the stringent WFE, stability, and stray light requirements for the TRO are described. Key words : Aeolus Satellite, ALADIN instrument, Lidar, optical design, UV optics manufacturing technologies
This paper describes the preliminary design of the so-called Transmit/Receive Optics (TRO) for the ADALIN lidar instrument on the future ADMAeolus weather satellite. The TRO is the central optical unit of the instrument, that feeds the optical signals from the laser source to the emitting/receiving telescope, and vice versa, the received back scattered signals from the telescope to the spectrometers for Doppler shift evaluation. Additionally, the TRO supports a calibration branch, that bypasses the telescope (from the laser to the spectrometers) and aims at levelling out the received signals in terms of wavelength and signal height changes due to wavelength and intensity variations of the laser. Since the spectral range of the ALADIN instrument is narrow (centred at 354.8 nm), the TRO makes use of refractive optics (lenses) to a high extend. A 1 nm narrow band interference filter has been implemented on the reception branch on the TRO to suppress disturbing background signals. Special features of the TRO are two so-called aberration generators on the emitting and calibration branch, with which an artificial astigmatism can be realised for eye safety reasons. An opto-mechanical concept has been realised with four afocal optical groups, which are connected by parallel beams. Different design options for the aberration generator are being discussed with clear preference of a pure lens solution. The performance of the optical subsystem is monitored by extensive simulations, which are shortly summarised. As a specific simulation example, the analysis and trade-offs of the aberration generator are given.
Fourier transform IR spectroscopy (FTIR) is well suited for establishing emission rates from sources of for example CH4, N2O, CO2 as important greenhouse gases and for NH3 as a pollutant causing severe damages to natural ecosystems. Since the gases mentioned above have spectral liens broadened to 0.2 cm-1, the resolution used for these measurements is 0.2 cm-1 too on a mobile instrument allowing resolutions up to 0.06 cm-1. In a first attempt, calibration spectra were taken from HITRAN92 based FASCODE calculations. Since test measurements revealed problems in determining accurate concentrations, own spectra were taken at a dynamic gas-mixing station. The absorption coefficients differ strongly from the simulations, for example for CH4 deviations are 19 percent max., for N2O 16 percent for NH3 15 percent. Calibration showed good linearity of absorbance vs. concentration up to absorbencies of 0.4 at the resolution of 0.2 cm-1.
Measurements with a mobile laboratory for FTIS remote sensing of pollution in ambient air and directed effluent streams (smokestacks and aircraft engines) are reported. The Double Pendulum Interferometer K300 and a multi-component radiative transfer analysis software were used to quantify the molecules CO, CO2, NO, NO2, N2O, SO2, HCl, H2O, CH4, NH3, HCHO and HC every 5 - 10 minutes in good agreement with in-situ sensors.
The FT-IR system K300, primarily used for environmental monitoring by means of remote sensing techniques, has been modified in such a manner that it could be used for remote monitoring of a SiC chemical vapor infiltration process (CVI). This comprised hardware adaptations to a CVI reaction plant at DASA (MBB), as well as development of analytical methods. First measurements showed the good performance of the K300 system at the reactor. A lot of gaseous species could be detected and qualitatively analyzed (concentration changes).
A mobile environmental laboratory has been developed. This laboratory consists of a van which is equipped with different environmental sensors. The FT-IR system K300 by Kayser- Threde is the key instrument. With this K300 the van can be used for remote measurements of the gaseous emissions from smoke stacks. In addition the laboratory is equipped with standard ambient air analyzers as well as meteorological sensors. A large battery system ensures current source free operation the whole day. Reloading of the batteries takes only one night. remote measurements with this van were carried out at different power plants. Several pollutants could be analyzed. First results are presented.
The described double pendulum interferometer is a newly designed FTIR spectrometer based on the Michelson interferometer type. The unique optical layout allows a compact design in spite of high resolution and offers a very high stability. The presented device K300 is constructed as a stable instrument for field measurements. Apart from absorption measurements of trace gases, an innovation in the field of environmental measurements is the monitoring of smoke stack pollution by remote sensing. First results of emission as well as absorption measurements are presented.
The design and the main features of the new double pendulum type
michelson interferometer (DPI) by Kayser-Threde are presented.
The advantages of this spectrometer in comparison to conventional Fourier spectrometers are discussed. The DPI is compact in
design, mobile, insensitive to vibrations and temperature changes and, thus, well adapted to field measurements. The spectrometer was applied to emission as well as immission measurements
of air pollutants. Several molecules could be identified and
their concentrations could be estimated. The detection limit of
the DPI yields 15 - 60 ppm depending on the analyzed gas for
emission measurements, 6 - 84 ppb for immission measurements.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.