Ordinary inter-satellite optical includes at least three optical paths for acquisition, tracking and communication, the three optical paths work simultaneously and share the received power. An optimal structure of inter-satellite optical communication terminal with single working optical path at each of working stages of acquisition and communication is introduced. A space optical switch based on frustrated total internal reflection effect is applied to switch the received laser power between the acquisition sensor and the communication sensor between the stages of acquisition and communication, this is named as power fusion which means power is transferred for shutting down unused optical path. For the stages of tracking and communication, a multiple cells sensor is used to accomplish the operation of tracking while communication, this is named as function fusion which means accomplishing multiple functions by one device to reduce the redundant optical paths. For optical communication terminal with single working path structure, the total received laser power would be detected by one sensor for each different stages of acquisition, tracking and communication, the link budget would be maximized, and this design would help to enlarge the system tolerance and reduce the acquisition time.
This paper summarizes the results of a dynamic link attenuation probability study in inter-satellites homodyne BPSK optical communication system. The impacts of the pointing and tracking error on the coherence receiving power are investigated analytically. To evaluate the requirement of optical system aberrations, the link attenuation caused by the aberrations is analyzed. By means of numerical simulation, the probability density function and the cumulative distribution function of bit error probability are calculated by the frequency histogram method.
The principle of Hartmann wavefront sensor is that the centroid angle deviation of spot equals to the mean slope of the
phase on the subaperture, but its precision is up to one of two assumptions: the beam is divided into plan wave and the
beam intensity distribution is uniform on each subaperture. When none of these two assumptions is satisfied in the
wavefront detection, the centroid angle deviation of far field spot is not exactly equals to the mean slope of the phase on
each subaperture, and finally the wavefront detecting error is produced. A similar case occurs when calibrating the
Hartmann wavefront sensor. The translation error of microlens arrays and the focal length differences of microlens arrays
would introduce defocuses on all subapertures, the centroid of the far-field spot is not the same as the mean slope of the
phase of calibrating beam when the calibrating beam has nonuniform intensity distribution, as a result, the calibration
error of Hartmann wavefront sensor comes out. Two formulas, which evaluate the calibration error associated with the
nonumiform intensity distribution and the defocus of microlens arrays are obtained in this paper, these formulas provide
theoretical supports to design and calibrate a Hartman Sensor required millesimal wavelength precision. Also a new
parameter is derived to characterize the nonuniformity of the intensity distribution.
The direction deviation of the reflected beam induced by the corner cube retroreflector (CCR) is respectively discussed
by geometrical optics approach and the principle of physical optics in this paper. A mathematical model was built to
calculate the beam's aberration due to the fabrication errors of the CCR. It can be concluded that the centroid direction
error of far field spot is much more appropriate to describe the reflection beam's direction deviation for a broad incident
beam, and the beam with even intensity distribution should be used to reduce its direction deviation.
Optical telescope systems with segmented mirrors require precise coalignment of their segments to achieve the
desired full near-diffraction-limit performance. The segment vertical misalignment (piston error) between the
segments must be reduced to a small fraction of the wavelength (<100nm) of incoming light. We have considered
an interferometric piston error measurement system based on a high-aperture Michelson interferometer layout for
accomplishing such objectives, The piston error between the segments can be extracted from the interferometric
fringes mismatching, The innovation introduced in the optical design of the interferometer is the simultaneous use
of monochromatic light and two-wavelength combination white-light source in a direct method for improving the
central fringe identification in the white-light interferometric phasing system. We find that this two-wavelength
combination technique can greatly increase the visibility difference between the central fringe and its adjacent side
fringes, and thus it offers an increased signal resolution. So make the central fringe identification become easier,
and enhance the measure precision of the segment phasing error. As a result, it is suitable for high-precision
measurement purpose and application in the segment piston error phasing system.
For the optical system of the telescope, with the increase in telescope size, the manufacture of monolithic primary
becomes increasingly difficult. Instead, the use of segmented mirrors, where many individual mirrors (the segments)
work together to provide an image quality and an aperture equivalent to that of a large monolithic mirror, is considered a
more appropriate strategy. But with the introduction of the large telescope mirror comprised of many individual
segments, the problem of insuring a smooth continuous mirror surface (co-phased mirrors) becomes critical. One of the
main problems is the measurement of the vertical displacement between the individual segments (piston error), for such
mirrors, the segment vertical misalignment (piston error) between the segments must be reduced to a small fraction of
the wavelength (<100nm) of the incoming light. The measurements become especially complicated when the piston error
is in order of wavelength fractions. To meet the performance capabilities, a novel method for phasing the segmented
mirrors optics system is described. The phasing method is based on a high-aperture Michelson interferometer. The use of
an interferometric technique allows the measuring of segment misalignment during the daytime with high accuracy,
which is a major design guideline. The innovation introduced in the optical design of the interferometer is the
simultaneous use of monochromatic light and multiwavelength combination white-light source in a direct method for
improving the central fringe identification in the white-light interferometric phasing system. With theoretic analysis, we
find that this multiwavelength combination technique can greatly increase the visibility difference between the central
fringe and its adjacent side fringes, and thus it offers an increased signal resolution. So make the central fringe
identification become easier, and enhance the measure precision of the segment phasing error. Consequently, it is
suitable for high-precision measurement purpose and application in the segment piston error phasing system. The
description about the expected interferograms and the feasibility of the phasing method are presented here.
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