A VIPA-based spectrograph with ultra-high resolution and wide band was designed and built by the astronomical photonics team in NIAOT. The fiber-fed spectrograph is compact (W × D × H: 350 mm × 350 mm × 150 mm) and designed to operate without temperature control measures. The spectrograph also provides a fast and accurate measurement of linewidths. Here we report the performances of the VIPA spectrograph, such as the spectral resolution and coverage, the precision of linewidth measurements, the stability with ambient temperature and data acquisition rate, etc.
High-resolution telescopic imaging is very important in astronomy. Super-resolution technology which breaks the diffraction limit of the imaging system can enhance the spatial resolution with compact setup and low cost. In this work, a novel super-resolution telescopic imaging method based on aperture modulation is proposed, and two different algorithms based on intensity extrapolation and image reconstruction for the recovery of super-resolution image are demonstrated respectively. With the help of aperture modulation, redundant information which contains high frequency components beyond the cut-off frequency of the imaging system is coded into the image sequence, and then they are extracted and used to reconstruct the super-resolution image by subsequent signal processing. Experimental results showed that the resolution was enhanced by 2.1 times for extended targets, and 3 times for point sources. Better performance is possible with the improvement of algorithm.
A conventional adaptive optics system utilizing a beacon light on or near the target for wavefront sensing is often used to compensate the phase aberrations of laser beam propagating through optically inhomogeneous media. However, there is no such a spatially coherent emitter could be used in most cases, one must rely on the reflection or scattering light from an uncooperative extended target itself to probe the atmosphere channel. In this paper, we show that an incoherent target return could be utilized to adaptively focus a collimated laser beam onto a rough target through atmospheric turbulence by simulation. A laser transmitting and receiver system combined with a wavefront sensorless adaptive optics system based on the modified stochastic parallel gradient descent (SPGD) algorithm simulation platform is established. The results show that all the maximum intensities among 1000 simulations increased and a single localized region of high intensity was achieved 78.7%. Additionally, we verified the system performance at different turbulent strength and discuss these limitations.
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