We report design of laboratory prototype for a compact infrared acousto-optic imaging spectro-polarimeter, which may be implemented for remote or close-up analysis of planetary surfaces. The prototype concept contains a telecentric optics, apochromatic design over the bandwidth of 0.9–3.4 μm, and simultaneous imaging of two orthogonal linear polarizations of the same scene at a focal plane array (FPA). Two acousto-optic channels, the near-IR (0.9-1.7 μm) the mid-IR (1.5–3.4 μm), were developed with spectral resolution of 100 cm<sup>-1</sup> (10 nm at 1 μm) and 25 cm<sup>-1</sup> (20 nm at 3 μm) respectively. When imaging samples, the spatial resolution of 0.2 mm at the target distance of one meter was reached. It corresponds to 100 by 100 elements resolved at the FPA for each of the two light polarizations. This type of instruments may be considered as a potential reconnaissance and analysis tool for future planetary or moon landers and rovers to study spectral and polarization properties of the regolith.
We report on the acousto-optic spectral imaging system designed for speckle imaging observations and interferometry. The setup is based on a non-collinear paratellurite acousto-optic tunable filter (AOTF). Breadboard prototype of the system with an in-house fabricated AOTF has been designed and commissioned. The prototype spectral range covers the band from 3600 to 5800 Å. Arbitrary spectral transmission function synthesis of the AOTF was applied. The AOTF spectral transmission bandwidth is programmable in the range from 44 to 875 cm<sup>−1</sup> (12.5–250Å at the wavelength of 5050Å). The AOTF is synchronized with the CCD readout and can be used as a global electronic shutter with on/off switching time of 12 μs. The exposure is adjusted as any integer multiple of 4.5 μs.
We report design of acousto-optic imaging spectrometer for spectral and polarimetric photometry and commis- sioning of the instrument at 0.6-m F/12.5 telescope at the Southern Astronomical Station of Lomonosov Moscow State University. The spectrometer was operating over the spectral range 3800–5800 Å with the passband of 10 Å at the wavelength of 5000 Å The imaging spectrometer could be used for observations of objects with the minimum brightness of 12.5 mag (for 0.6-m telescope, 120 s exposition, and SNR∼10). Spatial resolution of the spectrometer was estimated better than 1.2”, and the field of view was ∼250”.
We propose a concept of an imaging near-IR spectrometer for sensing of planetary surfaces. This instrument is intended to analyze mineralogical and, in some cases, petrographic composition of the upper surface layer in the planetary regolith; to identify and monitor OH/H2O bearing minerals and water adsorption in this layer. The scheme of the spectrometer was designed on a basis of an acousto-optic tunable filter (AOTF) that allows imaging of samples in two orthogonal polarization planes simultaneously. Images are registered as a light (e.g. solar one) reflected and scattered from an observed target in the near infrared spectral range. The AOTF’s electrical tuning provides fast and flexible spectral scanning of an image through whole the range analyzed – potentially, ten microseconds per a spectral point. Thus, it is possible to explore reflectance spectra of specified areas on a sample and to detect its minerals composition and microstructure variations. In parallel, one can estimate polarization contrast at different wavelengths thanks to the AOTF’s birefringence properties. In this paper we report design and performance of a laboratory prototype for the near-IR spectro-polarimeteric imaging AOTF system operating in the spectral range from 0.8 to 1.75 μm. Reflectance spectra of some minerals were measured with the spectral resolution of 100 cm<sup>-1</sup> (passband 10 nm at 1 μm). When imaging samples the spatial resolution as high as 0.5 mm was reached at the target distance of one meter. It corresponds to 100 by 100 resolving elements on the CCD matrix for each of two polarizations of the reflected light. Such a concept is also being designed for the spectral range from 1.7 to 3.5 μm.
We report design and prototype performance of an acousto-optical imaging spectropolarimeter aimed for the 2.5 m telescope at Caucasian Mountain Observatory of Lomonosov Moscow State University. Special geometry of the acousto-optical interaction provides two diffracted beams polarized along the slow and the fast axes of the crystal. The optical system of the spectrometer consisting of plane and elliptical mirrors delivers the images of the object with two orthogonal polarizations to a single CCD matrix, increasing the focal ratio of the telescope.
Idea of ultrahigh cosmic rays (UHECR) measurement from satellites was suggested by Linsley in 1981 and since
has being developed into projects of cosmic rays telescopes for International Space Station (ISS): JEM-EUSO -
to be installed on the Japanese experimental module and KLYPVE - on the Russian ISS segment. A series of
space-based detectors for measurements of background phenomena in those telescopes were developed in Russia
(Universitetsky-Tatiana, Universitetsky-Tatiana-2 , Chibis satellites). The satellite Lomonosov with UHECR
detector TUS on its board will be launched in 2013. TUS contains multi-channel photo receiver and Fresnel-type
mirror manufactured with use of special multi-layer carbon plastic technology in RSC “Energia". In this paper
one and two component optical systems with 360 cm entrance diameter and 400 cm focal distance for wide angle
detector KLYPVE are studied. In one component case using generalized Davies-Cotton systems (Fresnel-type
mirror with ellipsoidal gross surface) it is possible to obtain 8-10° field of view (FoV) with focal spot size less
than pixel size equal to 15 x 15 mm. In two component system (parabolic mirror and a Fresnel lens, mounted
close to photo receiver) it is possible to increase FoV up to 10-12° and significantly simplify the primary mirror
The MASS (Multi-Aperture Scintillation Sensor) instrument consists of a 14-cm off-axis reflecting telescope and a detector unit which measures the scintillations of single stars in four concentric zones of the telescope pupil using photo-multipliers. Statistical analysis of these signals yields information of the vertical turbulence profile with a resolution of dh/h=0.5. We describe the instrument and present the results of its first field tests, including comparisons with DIMM seeing monitor and generalized SCIDAR. MASS will be used to obtain the extensive statistics of turbulence profiles at potential sites of future giant telescopes, as needed to predict the quality of adaptive seeing compensation.
In recent years there were published many papers detailing an important problem on the use of adaptive means and adaptive optics systems to improve the image of objects observed through the atmosphere. These papers concerned the theoretical and technical aspects of the problem on constructing an adaptive optical telescope.