The divergence angle is very important index in space laser communication for energy transfer. Typically, the large aperture telescope as optical antenna is used for angle compression, and the divergence angle of communication beam is usually calculated by diffraction limit angle equation 1.22λ/D. This equation expresses the diffraction of a spherical wave through a circular aperture. However, the light source commonly used laser with a Gaussian distribution, and the optical antenna is central obscurations. The antenna parameters which is obscuration ratio and Gaussian beam apodization were significantly relative with the far field energy. In this study, we obtain the mathematic relation between the divergence angle, energy loss and the antenna parameters. From the relationship, we know that the divergence angle smaller as the increase of antenna obscuration ratio. It would tend to enhance the far-field energy density. But a larger obscuration ratio will increase the energy loss. At the same time, the increase of Gaussian beam apodization resulted in the energy of first diffraction ring was raised but the radius of first ring was increased. They were conflict. And then, the antenna parameters of trade-off was found from curves of obscuration ratio and curves of divergence angle. The parameters of a Cassegrain antenna was optimum designed for the energy maximization, and considerd the apodization from mechanical structure blocking. The long-distance laser communications were successful in these airborne tests. Stable communication was demonstrated. The energy gain is sufficient for SNR of high-bandwidth transmission in atmospheric channel.
In the free-space laser communication, there is a strong need for a technology that can decrease the size of the diffraction spot in the receiver port, because a smaller diffraction spot in the receive port makes the transmit data more secure. In this paper, instead of the usage of the larger size aperture lens in the free-space laser communication system, we introduce a diffractive superresolution technology that changing the received information laser beam into radially polarized beam which is focused on the detector array. In the paper, firstly, the conversion method of the information natural light which the optical antenna received to the radially polarized beam is discussed in detail. Then, in the focal plane, the transverse intensity distribution expression near the focal point for the radially polarized laser beam are presented, and the numerical simulation results of the intensity distributions around the focal point on different numerical apertures (NA) are given. The full width at half-maximum (FWHM) values of the main lobe are considered for the standard of the spot size. Through a comparison of the focal point FWHM values with the natural light and radially polarized beam, we judge the superresolution performance of the receiver optical system with radially polarized beam on different NA of 0.4, 0.6 and 0.75. We find that the method of focusing with radially polarized beam generates a smaller spot size than the Airy spot size when the NA is no less than 0.6; when the NA reach to 0.75, the resolution is 1.5 times than the diffraction limit. But it will decrease the light power in the process of natural light converted to radially polarized beam. When the communication laser is polarized laser, the energy loss can be reduced to around 20%. This technology can be applied when the laser energy is not the main concern in the communication.
With urgent demand for an integrated information network and development of free-space laser communication technology, research on high-rate laser communication networking technology is vital. This study analyzed the technical difficulties related to space laser communication networking and proposed a laser communication networking solution. A wide-angle beam expander and dual-rotating prism group were incorporated into a multiaccess optical laser communication antenna. The wide-angle beam expander collects signal light from different directions; the dual-rotating prism group tracks different targets simultaneously. This paper presents an overall scheme allowing multiaccess free-space laser communications based on the optical antenna described and the associated relay optics and transceiver subsystems.
As a kind of light-weighted and convenient tool to achieve stereoscopic vision, virtual reality glasses are gaining more popularity nowadays. For these glasses, molded plastic lenses are often adopted to handle both the imaging property and the cost of massive production. However, the as-built performance of the glass depends on both the optical design and the injection molding process, and maintaining the profile of the lens during injection molding process presents particular challenges. In this paper, optical design is combined with processing simulation analysis to obtain a design result suitable for injection molding. Based on the design and analysis results, different experiments are done using high-quality equipment to optimize the process parameters of injection molding. Finally, a single concave-convex lens is designed with a field-of-view of 90° for the virtual reality 3D glasses. The as-built profile error of the glass lens is controlled within 5μm, which indicates that the designed shape of the lens is fairly realized and the designed optical performance can thus be achieved.
Thermal properties of diffractive optical element and method of design athermal hybrid infrared optical system are introduced. Athermal LWIR hybrid infrared optical system for no cooled staring detector is designed. The system consists of three lenses, the effective focal length is 100mm，the relative aperture is 1:1,the wavelength spectrum is 8~11μm, the field view is 14° and the total optical length is just 140mm. The result shows that the modulation transformation function at 17lp/mm is greater than 0.6 between -40-60°C，which prove that the system can work correctly at a large temperature range.
Nowadays, the waveguide has the advantages of small thickness and light weight so that it attracts more and more attention in the field of near-eye display. However, as a major problem, stray lights generated in the waveguide seriously degrade the display quality. In this paper, a geometrical waveguide with a beam-splitting mirror array (BSMA) is designed by using the non-sequential ray-tracing software LightTools, and great efforts are paid to study the causes and solutions of the stray light. With mass calculation and optimization based on the criterion of stray light/useful light ratio, an optimum design with the least amount of stray lights is found. To further eliminate the stray light, a novel structure that couples the rays into the waveguide is designed. The optimized waveguide has a FOV of 36° in the pupil-expanding direction of the waveguide, with stray light energy reduced to 1% over the useful light, the exit pupil diameter is 11.6mm at an eye relief of 20mm and the thickness is 2.4mm.
The aero optics effects caused by high speed flight may have a serious impact on the performance of space laser communication systems. In the field of space laser communication technology engineering and its practical application, this is a research problem that is highly significant. For the complex flow field that is generated by the interaction between the aircraft surface and air, the aero optics effects are usually divided into two parts, namely, laminar flow and turbulent flow. This paper discusses the principle of how the aero optics effect causes the image of the space laser communication optical system to blur and leads to a dispersed spot. The research focuses on the additional focal length (AFL) effect caused by the laminar flow field, a simulation analysis of the relationship between the flight altitude, speed, window shape and the system performance, and provides solutions to the defocus phenomenon that has been observed in airborne tests. Finally it is hoped that the paper can provide a solution that effectively compensates for the AFL effect on laser communication optical systems, and improves the communication between aircrafts.
A new method that adopt fiber laser phase array source to form all optics
network in the deep space communication was proposed in this paper. The far-field
light intensity figure of 1.55μm fiber laser phase array source was simulated, and the
scanning range with changing among array components the phase was obtained. The
number of array components was 3×3, wavelength was 1.55πm, and core radius
was 10μm. The scanning range was ± 0.9909° when the distance of array
components was 80μm. It was found that applying fiber laser phase array source can
achieve scanning advantages with dynamic range in the all optics network.
Space laser communication is the perfectly choose to the earth integrated information
backbone network in the future. This paper introduces the structure of the earth integrated information
network that is a large capacity integrated high-speed broadband information network, a variety of
communications platforms were densely interconnected together, such as the land, sea, air and deep air
users or aircraft, the technologies of the intelligent high-speed processing, switching and routing were
adopt. According to the principle of maximum effective comprehensive utilization of information
resources, get accurately information, fast processing and efficient transmission through inter-satellite,
satellite earth, sky and ground station and other links. Namely it will be a space-based, air-based and
ground-based integrated information network. It will be started from the trends of laser communication.
The current situation of laser multi-point communications were expounded, the transmission scheme of
the dynamic multi-point between wireless laser communication n network has been carefully studied, a
variety of laser communication network transmission schemes the corresponding characteristics and
scope described in detail , described the optical multiplexer machine that based on the multiport form
of communication is applied to relay backbone link; the optical multiplexer-based on the form of the
segmentation receiver field of view is applied to small angle link, the optical multiplexer-based form of
three concentric spheres structure is applied to short distances, motorized occasions, and the
multi-point stitching structure based on the rotation paraboloid is applied to inter-satellite
communications in detail. The multi-point laser communication terminal apparatus consist of the
transmitting and receiving antenna, a relay optical system, the spectroscopic system, communication
system and communication receiver transmitter system. The communication forms of optical
multiplexer more than four goals or more, the ratio of received power and volume weight will be
Obvious advantages, and can track multiple moving targets in flexible.It would to provide reference for
the construction of earth integrated information networks.
With the urgent need for the development of high data rate transmission of information and
high-resolution observation techniques, research on high-speed laser communications networking
technologies is imminent. This article analyzes the basic requirements of space laser communication
links and the technical difficulties and achieve in the network need to be solved. The optical principle
of the networking were proposed, studied technical solutions of a laser can be used for communication
between multiple targets simultaneously, designed with the rotating parabolic antenna to the base of the
optical multi-mirror stitching structure, as well as transmitting and receiving relay optical system with
APT system, a new technical approach was provided for the space laser communication link
According to the parabolic features, for the incident light firing at the direction of focus, the reflected
light is parallel to the optical axis. But the energy efficiency is low for this type of surfaces, only small
portion of the energy can be received. So it is designed to form the multi-mirror mosaic structure with
parabolic base. The normal of each mirror is perpendicular to the tangent of the paraboloid. The size,
shape, number and the combination way of mirrors are designed and optimized according to the orbit
position and number. Each mirror is controlled to perform the movement in the horizontal and azimuth
directions, in this way the antenna has certain stability and light deflection. With this antenna,
communication can be realized for objects in different orientations at the same time for 360° in
horizontal direction and big field of view in azimuth direction.Finally, it prospected the application
Visible Light Communications (VLC) has become an emerging area of research since it can provide higher data
transmission speed and wider bandwidth. The white LEDs are very important components of the VLC system, because it
has the advantages of higher brightness, lower power consumption, and a longer lifetime. More importantly, their intensity
and color are modulatable. Besides the light source, the optical antenna system also plays a very important role in the VLC
system since it determines the optical gain, effective working area and transmission rate of the VLC system. In this paper,
we propose to design an ultra-thin and multiple channels optical antenna system by tiling multiple off-axis lenses, each of
which consists of two reflective and two refractive freeform surfaces. The tiling of multiple systems and detectors but with
different band filters makes it possible to design a wavelength division multiplexing VLC system to highly improve the
system capacity. The field of view of the designed antenna system is 30°, the entrance pupil diameter is 1.5mm, and the
thickness of the system is under 4mm. The design methods are presented and the results are discussed in the last section of
this paper. Besides the optical gain is analyzed and calculated. The antenna system can be tiled up to four channels but
without the increase of thickness.
With the developing of the space laser communication link, the performance index including higher transfer speed,
extending transfer distance, and environmental adaptability, all ask the system accuracy and indexes improving. Special
the developing near space platform, its environmental is extremes, the near space drone and other airplane flight speed is
very quickly from the subsonic to supersonic. The aero optics effect caused by high speed will generate a thin turbulent
air layer. It affects the performance of laser communication optical system by laser light vibration, deviation and so on,
further more affects the performance of laser communication system working performance, even can’t communication.
Therefore, for achieving optical system indexes, we need do more research in optical system near space aero optics
In this paper, near space link environmental characteristic are researched. And on the base of the aero optics theory,
computer simulating method is applied to analyze the relationship among the altitude, the flight speed and the image
dispersion. The result shows that, the aero optics effect cannot be ignored when the terminal is in low altitude or is
moving with supersonic speed. The effect must be taken into considered from overall design. The result will provide the
basis of research design.
Space laser communication system uses laser light as the information carrier to achieve intersatellite communication.
And the terminal of laser communication is the key part. It is necessary to accomplish the test of performance and
function, validation and judgment. The test of dynamic and static performance for terminal is the basic content and
necessary steps on the reliability of space laser communication terminal. So the reach on ground test technology of space
laser communication is more important.
This paper mainly describes the test system of integrated performance for space laser communication terminal. The test
range of system includes two essential parts, i.e, static test and dynamic test. Static test includes the angle of divergence,
the coaxially of axis, communication performance and so on. Dynamic test includes the test of capture ability at dynamic
and disturbance environment, and the test of dynamic track precision.
The test system has achieved accurate test of dynamic track precision and multi-performances test of terminal based on
simulatin at real working environment. The test result could present the anti-disturbance performance, anti-noise
performance, and dynamic communication performance of the terminal.