Aiming at the complex structure, difficult installation and high cost of the multispectral camera optical system used for phenological observation, a miniaturized and snapshot multispectral camera scheme is proposed. A compact and multi-channel image parallel optical system is designed by using a four-sided pyramid prism as an important optical element. The field-of-view of the system is ±3°, the working band is 400nm-600nm, the focal length is 50mm, and the F number is 5. The design results show that the single wavelength modulation transfer functions (MTF) at Nyquist frequency is better than 0.5, the root mean square radius (RMS) of all field of view is less than 7.4μm, and the distortion is less than 0.5%, which can meet the design requirements of multispectral cameras.
Space optical remote sensors play an important role in earth observation, space situation awareness and astronomy exploration. The optical resolution of space remote sensing system is constantly improved. Several new techniques for realizing ultra-high resolution of spatial optical remote sensors are reviewed. The research status and application prospects of these new technologies are discussed, mainly including synthetic aperture optical system, Fourier ptychography and intensity correlation imaging. The critical technical problems of these new technologies in spacebased and ground-based optical remote sensing engineering are summed up.
Synthetic aperture lidar is a new ultra-high resolution optical imaging instrument, but its reception field is very narrow which is subject to the "antenna theory". In this paper, the antenna efficiency theory is used to explain the antenna theory and the method of enlarging the field of view of the synthetic aperture laser radar. Then the increase range of the field angle of the three methods is deduced by heterodyne efficiency simulation. The simulation results show that the focal plane heterodyne detection optical path of the wide-beam local oscillator beam focal plane has the ability to improve the heterodyne efficiency of the edge field of view by reducing the heterodyne efficiency of the central field of view. The focal plane heterodyne detection optical path of the array detector requires the detector whose pixel size less than 3 times Airy spot radius covers the whole field of view, which can increase the maximum 1.83N times compared to the antenna theory. The effective field of the pupil plane heterodyne detection optical path of the array detector has nothing to do with the magnification of the telescope, the pupil diameter, the size of the detector, etc., which can be increased by N times as compared with the antenna theory.
The thermal stability of optical antennas is a key parameter determining the performance of satellite optical communication links. The effects of uniform temperature changes on the performance of a Cassegrain optical antenna are discussed. In addition, a simple theoretical model is proposed to describe the defocusing distance and wavefront aberration (power) as a function of temperature. Through the theoretical model, the thermal stability can be quickly assessed in the optical design stage. The alignment data and thermal experimental results are consistent with the theoretical model.
The use of line-plane-switching infrared fiber bundle to achieve wide field of view push-broom infrared imaging has been studied with experiment. In this technology, the linear array end of the imaging fiber bundle is used as a long-linear array infrared detector, and the plane array end of the bundle is coupled by a mature small scale Infrared Focal Plane Array (IRFPA). It can evade the difficulty of getting the long-linear array infrared detector directly, and has a signally significance to the development of internal infrared imaging technology. Based on the introduction of the composition, working principle of this novel infrared optical system, the system principle-demonstrating experiment has been accomplished. The line-plane-switching fiber bundle used in this experiment is 64×9 format plane array and 192×3 format linear array. It is made from chalcogenide glass fibers, possessing core (As<sub>40</sub>S<sub>59.5</sub>Se<sub>0.5</sub>) of 45 μm, cladding (As<sub>40</sub>S<sub>60</sub>) of 5 μm, and error of 1% in diameter. Perfect imaging results prove that this novel technology is feasibility and superiority. The analysis of the experiment makes a foundation for the subsequent further verification experiments.
Relay lens is an important element for infrared system coupled with imaging fiber bundle. According to the basic composition and structural characteristics of infrared system coupled with imaging fiber bundle, this paper put forward the general principle and method of its relay lens design, then a material relay lens has been designed by ZEMAX with definite performance index. It has a working spectral coverage from 3.7μm to 4.8μm, focal length of 33.5mm, magnification of -0.6, linear field of view of 12mm, objective numerical aperture of 0.15. It is objective telecentric and is adapted to the relay of infrared detector and imaging fiber bundle. The total lens has two aspheric surfaces and only four pieces of singlet. Its MTF value is 0.7@17 lp/mm, and distortion is -0.19%. After necessary tolerance analysis and structural design, this relay lens has been fabricated. The optical performances fulfill the design requirements and clear images have been got by this lens. These prove the validity and rationality of the design method. It gives a foundational guidance for such relay lens design.
The chemical element and mineral rock's abundance and distribution are the basic material of planetary geology
evolution research<sup> </sup>, hence preterit detection for composition of Mars surface substance contains both elements sorts
and mineral ingredients. This article introduced new ways to detect Mars elements and mineral components, Laser
Induced Breakdown Spectroscopy (LIBS) and Raman Spectroscopy (RS) which have distinct advantages, such as work
over a long distance, detect rapidly, accuratly and nondestructively. LIBS and RS both use laser excitation to shoot the
substance of Mars exciting new wavelengths. The techniques of LIBS and RS in laboratory are mature, besides the
technique of LIBS is being used in MSL (Chemcam) now and RS will be used in ExoMars. Comparing LIBS and RS's
detection results with XRF and APXS, Mossbauer spectrometer, these existed Mars surface material detection
instruments,and the Infrared spectrometer, Mid-IR, they have more accurate detection results. So LIBS and RS are
competent for Mars surface substance detection instead of X-ray spectrometer and Mossbauer spectrometer which were
already used in 'Viking 1' and 'Opportunity'. Only accurate detection results about Mars surface substance can lead to
scientist's right analysis in inversing geological evolution of the planet.
Imaging spectrometers based on prism-grating-prism (PGP) have advantage of direct vision, as a basis for the design of an optical system for a spectrometer and camera dual-use, the system can plug the light splitting element to switch between the spectrometer and camera. This paper has discussed the working principles and structure of the PGP and spectrometer, collimating and focusing lens design principles, then the design result has been presented. The spectral range of the system is 400-800nm, the pixel size of CCD used is 10um × 10um, 1010 × 1018 pixels, the object space numerical aperture is 0.1. In order to reduce the cost and eliminate aberration, collimating lens and focusing lens have symmetric structure, in order to improve the diffraction efficiency, PGP uses the volume phase holographic transmission grating. After optimization the design by ZEMAX software, the whole spectral range resolution is better than 1nm in average, the MTF at Nyquist frequency is greater than 0.7, the length of the whole system is 87mm.