This PDF file contains the front matter associated with SPIE Proceedings Volume 11185, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists

Glare and visual discomfort are important factors that should be taken into account in illumination design. Conventional freeform optics offer perfect control over the outgoing intensity distribution, but few control over the near-field luminance distribution. Observing the emitted light from a high-brightness LED through a freeform lens, yields a high peak luminance that can result in glare. Diffusors can be used to reduce these peak luminances, but such components do not offer accurate control over the resulting intensity pattern. An alternative approach to reduce the observed peak luminance is by spreading the emitted light over multiple optical channels via freeform lens arrays. Such freeform arrays still allow excellent control over the resulting intensity distribution. In this paper the design of freeform lens arrays is discussed in both 2D and 3D. The possibilities and main limitations of the resulting components are discussed in detail by considering a few examples. In order to understand the design algorithms for multi-channel freeform optics, the paper starts with a brief introduction to the design of single-channel freeform optics for obtaining prescribed illumination patterns.

In this contribution we introduce the (generalized) Monge-Ampere equation, defining the shape/location of an optical surface. In particular, we consider a lens with one freeform surface and a freeform reflector. For the lens we consider a source emitting a parallel bundle of light and for the reflector we assume a point source emitting light radially outward. In both cases the target distribution is a far-field intensity. As numerical solution method we propose a least-squares method, which is a two-stage method. In the first stage the optical map is computed, and subsequently in the second stage, the shape of the optical surface. We demonstrate that our method can handle complicated source and target distributions.

With the development of aerospace technology, the demand for solar simulation technology is getting higher and higher. The realization of solar simulation technology mainly has the following two ways: solar simulator and solar irradiation lamp array. The main applications of solar irradiation arrays are in the fields of aerospace, automobile and vehicle, material performance testing, agricultural breeding, etc. Compared with solar simulators, the structure is simple, economical and has a large irradiation area. The Beijing Institute of Satellite Environmental Engineering has successfully developed a single-sided wall vertical arrangement lamp array. The successful irradiation area of Xi'an JiaoTong University is 2.0m*1.5m, the irradiation is 1000w/m2, and the unevenness is better than ±5%. Lighting system. This design meets the requirements of thermal flow simulation of military aircraft cabins, improves the accuracy of heat flow simulation, and establishes a set of high-power radiation simulation devices. Through design simulation, it can be seen that the irradiation area of this heat flow simulation irradiation system can reach 1500mm*3500mm, at work. Within 1m, the irradiation energy is continuously adjustable from 0.8 to 1.5sc, the maximum radiant energy can reach 1.8sc (1sc=1353w/m2), and its uniformity can reach ±6.7%. The device can be used for aerospace components of the sun. Irradiation environment simulation test, etc.

The application of Computer- Generated Hologram (CGH) in spatial optical field modulation has greatly promoted the advancement of cutting-edge technologies such as ultra-precise measurement, optical tweezers, super resolution. However, the current processing of CGH is mainly based on microlithography technology. The minimum line width and processing accuracy of CGH have become a crux that limits its further application. In response to the crux, this paper proposes a liquid crystal CGH based on spatial light modulator (SLM) interference exposure method and photoalignment technology, combining the advantages of optical holography and computer-generated holography, aiming at achieving design and fabrication of high precision, maskless, rewritable, sub-micron linewidth liquid crystal CGH. This paper mainly elaborates the principle and design method of the liquid crystal CGH, laying a theoretical foundation for its subsequent widespread application.

The intrinsic markers of nanoscale morphological alteration in fixed tissue biopsy referred to as disorder strength and local correlation length, which can be easily and time-efficiently obtained from quantitative phase images, are introduced. After presenting how to extract these markers from quantitative phase images obtained by highly sensitive quantitative phase imaging system, spatial light interference microscopy (SLIM), we demonstrate the effectiveness of these markers for diagnosis of benign and malignant breast tissues.

Sparse aperture structure can solve the problems that single-aperture structure with large aperture is difficult to process. It can solve the problem that large aperture is easy to be deformed and can reduce the weight and size of the optical system. The most ideal state of the sparse aperture is to obtain more light information with the smallest light-passing area. The current goal is to obtain the best image quality by researching the arrangement of sparse aperture. However, most of the current sparse aperture structures have the same sub-aperture’s diameter, which leads to a rapid decline of system's modulation transfer function in the mid-frequency band. In this paper, the structure of three sub-apertures surrounding the large sub-aperture called quasi four-mirror structure is proposed through theoretical analysis and MATLAB simulation. The proportion of the diameter of the central mirror of the structure and the diameter of the surrounding sub-aperture is established. This proportional relation can ensure that the actual cutoff frequency is maximized while the filling factor of the entire system is minimized, thereby obtaining higher frequency information. The structure also has a feature that allows uniform acquisition of the mid-frequency information to obtain more detail information of image. The results of imaging simulation show that the imaging quality of the structure is better than that of the four-mirror structure when the filling factor and the light-passing area are equal. The sparse aperture structure of the quasi four-mirror structure proposed in this paper can be applied not only to large-scale astronomical telescopes, but also to medical endoscopes.

Freeform surfaces are optical surfaces without linear or rotational symmetry. Their high degrees of design freedom liberate designers and engineers from restrictions on optical surface geometry, yielding compact and lightweight imaging systems with excellent optical performance. Freeform optics have become a competitive tool in the design of optical seethrough head-mounted display (OST-HMD) systems. In this paper, we present two different OST-HMD systems which have different optical different configurations and both employ freeform optics to correct and balance optical aberrations. In the optimization design of the two OST-HMD systems, we start from a spherical imaging system with an on-axis configuration, and then tilt and decenter each optical surface to find a starting point. In the final state of optimization, the order of each XY polynomial used to represent the freeform surface is gradually increased. The modulation transfer functions of the two OST-HMD systems are evaluated and the three-dimensional models of the two systems are also presented.

Aluminum mirrors with high reflectivity have a wide range of applications in the vacuum ultraviolet, such as for space observation, synchrotron radiation. Due to the oxidation of Al has great effect on the reflectivity below the wavelength of 160 nm, Al-protected mirrors have experienced significant development over the past years, particularly like Al overcoated with LiF, MgF₂. This paper focuses on Al mirror over-coated with LiF, MgF₂ and LiF+MgF₂ in the wavelength range of 105-130 nm. The mirrors are prepared by three steps thermal boat evaporation method. The reflectivity of mirrors in the wavelength range of 105~130 nm is measuring at the National Synchrotron Radiation Laboratory (NSRL) of China， and the structural properties have been analyzed using grazing incidence X-ray reflectometer. Compared the reflectivity of samples placed in the relative humidity of 40%, the reflectivity of Al + LiF mirrors has dropped significantly within 2 months, while the reflectivity of Al+MgF₂ mirrors almost has no change within 30 months. The reflectivity of Al +LiF+MgF₂ mirrors stored in the relative humidity of 40% performs well within 4 months and we will further study the time stability.

This paper reports a design process for high magnification mid-wave infrared continuous zoom lens. The process consists of algorithms for finding global paraxial solution, optimization strategies for balancing aberrations in all zoom configurations, and cam curve smoothing methods in opto-mechanical design. Using this process, a parfocal continuous zoom lens with F/4, magnification of 20× working with a 640x512 cooled 15μm pixel pitch detector array, has been successfully designed and fabricated. In principal, this design bases on a zoom and a focus group. The zoom group consisting of three separate moving lens subsets allows for a high magnification ratio of 20× and its parfocality during continuous zooming, while the focus group helps changing focal planes and ensures normal operation in a large temperature and observation range. The lens uses different optical surfaces varying from spherical to hybrid diffractiveaspheric form. This results in high optical performance with MTF approaching diffraction limit while keeping the overall system compact and light weight. For the coordination of lens movement in the zoom group, smooth cam curves having satisfactory stiffness and pressure angles were achieved by a smoothing method which maps different system focal length values with appropriate barrel rotation angles. The simulation of optical performance and experimental testing results will be presented. This zoom lens can be used in long range surveillance camera system.

For a three-mirror coaxial (TMC) space camera, the centralization of the primary mirror is an important measurement link in the process of optical processing and alignment. The centering of aspheric mirrors is generally divided into contact measurement and non-contact measurement. For contact measurement, the mirror is scanned in the mechanical reference coordinate system by using a three-coordinate instrument or a laser tracker. After fitting the mirror equation, the deviation data between the optical axis and the mechanical axis are obtained. For non-contact measurement, there are two ways of centering: using centralizer or using interferometer. The main content of this paper is to introduce the centering of the 1.3m primary mirror of a space camera. Firstly, the realizability and accuracy of different methods are analyzed. Centering of aspheric mirror with large aperture by centralizer is of low precision and difficult to realize. For contact method, the accuracy of centering with laser tracker is only 0.15 degree. However, the accuracy of the CMM centering method and the interferometric centering method can reach 0.005 degrees. Secondly, for the 1.3m primary mirror, the centering of the primary mirror is accomplished by using the above two methods. The results of the two measurement methods are compared. The maximum deviation of the two eccentricities is only 0.023 mm and 0.002 degree. For the centering of large aperture aspheric mirror, the CMM centering method and interferometric centering method have their own advantages. The interferometry method can realize in-situ measurement in optical processing.

The deflectometry enables high-precision wavefront measurement with large dynamic range. Traditional multi-step phase-shifting fringe-illumination deflectometric methods involve at least three sinusoidal phase-shifting fringe patterns and require a sequential projection, making it not feasible for the instantaneous measurement. In this paper, a colorcoded method with frequency-carrier patterns is proposed to achieve the instantaneous wavefront measurement based on deflectometry. With the color extraction from different channels, composite patterns in x and y directions can be well separated with a single shot. Then, the phase-shifting patterns encoded in different frequencies can be demodulated with the designed filters, by which the local wavefront slopes can be obtained simultaneously to reconstruct the wavefront under test. Both the numerical simulation and experiments are performed to validate the feasibility of proposed method. The proposed method provides a feasible way for the real-time and instantaneous measurement with large dynamic range based on deflectometry.

The deflectometry provides an optical testing method with ultra-high dynamic range. In this paper, a microscopic testing method based on deflectometric technique is proposed to quantitatively evaluate the microstructures according to the wavefront aberration. To achieve the real-time and accurate wavefront testing for microstructure evaluation, a colorcoded phase-shifting fringe pattern is applied to illuminate the test object. It avoids the sequential projection of multistep phase-shifting fringes in traditional deflectometry, enabling the transient wavefront testing. The feasibility of the proposed transient microscopic testing method is demonstrated by the experiment. The proposed method enables accurate and transient testing of microstructures with high dynamic range, minimizing the environmental disturbance.

Optic fiber imaging elements are used in weak visible light, X-ray imaging and high-energy particle detection imaging devices. They play an important role as input and output window materials of image intensifiers. Optic fiber imaging elements are arrays of tens of millions of micron-scale single optical fibers arranged regularly. The fabrication process requires several times of fiber drawing and secondary thermal processing such as hot melting pressure, torsion, and stretching. After these processes, there may be spots and linear chicken filaments that are called defects existed on the interface among the fibers and multi-fibers. Due to these defects, the quality of imaging is seriously reduced, and even the misjudgment or omission of image signal recognition can are caused. How to detect such defects has no an ideal solution. Currently, non-quantitative microscopic observation is generally used. This method, however, is high in misjudgment and low in detection efficiency. In this paper, a device for automatic detection of optical fiber image defects based on machine vision algorithms, including its working principle, structure, detection steps and characteristics are introduced. The device not only can automatically measure the size of each defect, but also can count the defect distribution according to the quality zones. The test results are stable and accurate. It is especially suitable for batch detection and research of optic fiber imaging elements.

A new approach for optical system with liquid lenses is proposed in this paper. The method integrates genetic algorithm and simulated annealing algorithm to evaluate not only the current configurations of liquid lenses but also the optimization trend of the optical system. It makes a closer link between the liquid lenses configurations and the entire optical system, which is different from other algorithms and leads to a better performance in the optical system with liquid lenses. The result presents about 17% improvements compared to the same optical system optimized by conventional algorithms, from the values of the modulation transform function.

In order to make the plan of aspheric surface testing more convenient and efficient, the dynamic range of aspheric surface by the non-null interferometry was studied. The rule of maximum dynamic range of aspheric surface by the non-null interferometry is: the fringes of the densest zone is not only at the margins of the pattern, but also in some middle one general zone, and can be distinguished all at the same time. Based on the aberration theory, an expression about dynamic range was deduced, which was an intuitive and accurate judging criterion. An example was made to verify the theory of dynamic range; and it is also proved that the retrace error can increase the dynamic range slightly by simulation.

We propose a liquid crystal (LC) hologram fabricated with photoalignment technology, for the measurement of a cylindrical surface. A standard cylindrical surface reflects the incident planar wavefront and generates an interferogram with a planar reference wavefront. Photoalignment azo-dye material is then exposed by the interferogram and aligned with desired orientations, following with depositing LC monomer to generate the designed phase information. After ultra-violet curing, the fabricated LC hologram plate can generate a standard cylindrical wavefront when illuminated with a planar wavefront. The minimal line-width due to the limitation of LC molecules is sub-microns, which is smaller than the limitation in traditional CGH. The systematic design of the measurement is proposed, followed by a demonstration simulation.

The stray light uniformity is one of the important factors affecting the signal-to-noise ratio of the optical astronomical telescope. It will cause regional differences in the background intensity of the detector image, resulting in a decrease of the differential photometry accuracy. The source that affects stray light uniformity is the inconsistency of the brightness of the sky background, which comes from moonlight, bright star, and city lighting pollution. During CCD reduction, the effect of background uniformity cannot be eliminated by dividing the flat field.

Star deletion method is used in real-time stray light analysis. It’s very convenient to achieve a ‘clear’ background image without stars in MATLAB. A contour map of stray light distribution for each object image will be given to demonstrate the background uniformity directly. The stray light uniformity analysis method is implemented by the following steps: 1) CCD reduction, including preprocessing of an object image with bias and flat field; 2) Histogram generation, performing star subtraction automatically based on ADU value and frequency; 3) Background stray light contour map generation, stray light uniformity and other parameters calculations. This method will calculate the uniformity of image surface in real time, provide background intensity distribution, statistical data of the CCD image and suggestion on compare star selection during CCD data processing and improve the photometry accuracy.

The designed wedge scanner has conventional raster scan pattern canceling the movement along one axis by rotating opposite direction, in which case the alignment of these two wedge scanners affects the imaging performance of the system. To align the wedge scanners more efficiently and effectively, 2nd split rays are used. The ray tracing was performed to predict the precision achievable. The sensitivity according to the movement of the scanner is dependent on the refractive index and slant angle of the wedge and was about 350 times more sensitive when the angle between two vertexes of wedge scanners reaches 1°. The goal was successfully achieved below 0.6 mm in the screen 5 m away, which is 1/4 of the alignment goal.

To assemble and align the optical system, it is required to minimize the sensitivity of the optical system while maximizing the performance. However, sensitivity increases as the performance is optimized. To balance the sensitivity and performance, an efficient sensitivity analysis method is established to confirm the sensitivity right after the optical design is complete. The simplified analysis method reduces the individual analysis time to 1/5 of the full analysis. As a result, the final performance met the requirement and the sensitivity was minimized reducing the complexity and time of the final design process to 1/5 compared to the previous program.

An in-fiber Michelson interferometer based on core mismatching for liquid refractive index sensing is proposed and demonstrated. The sensor can be simply fabricated by fusion splicing a section of thinned core fiber (TCF) to a standard single mode fiber (SMF) without any reflection coating. The experimental results show that the sensor possesses RI sensitivity of -111.58 dB/RIU in the RI range of 1.333-1.380 RIU. The liquid temperature cross-sensitivity is experimentally analyzed and reveals that the measurement error of the liquid RI caused by temperature is -0.89×10-6 RIU/℃ in water temperature range of 25℃-80℃. The advantages of easy fabrication, high sensitivity, working on reflective intensity detection and compact size make the proposed sensor can offer promising applications in chemical, biomedical and petrochemical fields.

A secondary imaging convergence system is designed for a cooled infrared optical system with three Germanium lenses. An optimal design method for low stray radiation is proposed. Compared with the traditional method, stray light analysis shows that the new design method can suppress stray radiation by 23.87% more than the traditional method.

Surface reconstruction technology needs to fit the collected point cloud data into an expression with a complete base function. How to improve the fitting accuracy of surface reconstruction is the focus of this research. In this paper, aiming at the surface fitting model based on Gaussian radial basis function(RBF), the influence of shape factor selection on surface fitting accuracy is studied, and a new method for calculating RBF shape factor is proposed. The shape factor is connected with the size of the surface to be fitted, which strengthens the relationship among the kernels. Taking the given point cloud data as an example, the simulation experiments were carried out, and the fitting accuracy of different shape factors was compared, and the curved surfaces of different shapes were fitted. The results show that the accuracy of surface fitting can be improved by choosing shape factor combined with the size of fitting area; surface fitting based on RBF is suitable for the surface with small curvature and gentle surface; RBF can be used for the description of non-rotational symmetric surface, but the fitting accuracy will decrease.

A method of continuous zoom multiple configuration, with a micro lens array and core optics is attempt to establish model by novel principle on resonance energy transfer and high accuracy localization, by which the system resolution can be improved with a level of a few nanometers. A comparative study on traditional vs modern methods can demonstrate.

Nowadays, freeform optical surfaces are applied for forming of the required LIDC. There are several freeform optics design methods. In case when the optic lens is the lathe object, it is handier to use Light Energy Mapping Design Method. Nevertheless, this method has problem concerned with hotspot appearance in the center. The authors of the article propose an improved algorithm for designing freeform optics with two surfaces with a wide beam angle, designed to form illuminance uniformity and exclude the appearance of hotspot. According to the proposed algorithm, a lens was designed and the possibility of using was evaluated.

The article is devoted to simulation of photorealistic images of materials with fluorescent properties. Usually measurements and simulations of scattering surfaces of objects with fluorescent properties is complex and expensive task. The source of problem is dependence of spectral characteristics of output scattered light from spectral characteristics of input light. There are two methods to simulate complex light scattering of similar materials. The first method is based on measurements of bi-directional scattering functions (BSDF) describing surface scattering. The second approach is based on total reconstruction of parameters of VS medium. Simulation of real ray propagation inside of fluorescent volume scattering medium is complex and time consumed task because of huge number of ray interactions with fluorescent scattering agents especially if their concentration is significant. We propose alternative method to simulate fluorescent materials. The approach does not require complex and expensive measurements of “fluorescent“ BSDF. A hybrid method to measure and simulate fluorescence objects is proposed. The specular part of scattering can be simulated with BSDF based on measurements of usual material without fluorescence effect. Note only directions close to specular direction are used from this BSDF. Diffuse part of scattering is simulated with standard spectrograms well-known in many description of fluorescence: fluorescence efficiency and fluorescent emission. This separation of fluorescent and “usual” part of scattering allows effective use of different techniques for visualization from rather simple Backward Ray Tracing to more complex approaches of ray visualization which use combined forward and backward techniques of ray tracing.

The article describes the approach that allows to reconstruct the image formed by the video see-through mixed reality system corresponding to the convergence of the device user eyes. Convergence is defined by the user eye pupils position acquired from the mixed reality device eye tracking system. The image reconstruction method is based on the use of an extended (2.5-dimensional) representation of the image obtained, for example, using a 3D scanner that builds a depth map of the scene. In the proposed solution, lens optical systems that form images of the real world on LCD screens and eyepieces that project these images into the user eyes do not change their characteristics and position. The image is reconstructed by projecting the points of the original image to the image points corresponding to the required convergence by the method of "refocusing" at a distance for each point. The advantages and disadvantages of this method are shown. An approach is proposed that reduces visual perception discomfort caused by an ambiguous distance to the image point, for example, in the case of mirror or transparent objects. Virtual prototyping of the mixed reality system showed the benefits of the proposed approach to reduce the visual perception discomfort caused by the mismatch between the convergence of human eyes and the images formed by the lenses of the mixed reality system.

Optical components are being used more and more extensive in the most areas of production and human life, therefore improving the quality control of optical elements manufacture is high priority task when manufacturing any type of optical element. Every aspect of the production process directly impacts the final product quality and reliability level. In the process of optical elements manufacture, after determining the overall product quality requirements, the next most important thing is to clarify and implement the quality indicators of each product subsystem. So, after the quality requirements of the optical element is determined, the next step that should be done to ensure the quality of final product is measurements and testing work by the professional trained staff. The measurement and test job itself is also a system engineering, because it not only includes the metering and testing hardware (e.g. instruments, equipment, etc.) but also includes software work such as metering management and metering transmission. The quality control of optical components is a process that includes both quality management and the implementation of specific processing and testing methods. Optical component processing plants can use the following methods to improve and control the consistency of the quality of the finished optical elements: learn and use new optical component processing techniques, use numerical control technology, use advanced processing and inspection equipment, proficient in process inspection and finished product inspection methods. In this article we present an example of implementation of the quality control phase in the optical elements manufacture process.

The washing floodlight is a sort of optoelectronic equipment for the use on vessels which contain helipad, designed as a visual landing aid for the helicopter. Usually the washing floodlight is installed directly on the edge of deck, while the installation site should not be too high, normally lower than 350mm is recommended. In addition, since floodlight generally provides high and relative uniform illumination for a larger deck surface, it is necessary to have a reasonable light intensity distribution, high light intensity and high light energy efficiency. Meanwhile, the floodlight need to provide not only visible light but also infrared illumination to coordinate with night vision goggle. This paper provides a washing floodlight design with high light intensity and high average illumination. The illumination optical system consists of two separate portions, namely refraction and reflective illumination optical system. The refraction illumination optical system is a cylindrical lens with free-form surface, the upper part of lens is responsible for small angle illumination (about 0° to -5 ° in the vertical direction), while the nether part is responsible for large angle illumination (about -5 ° to -30 °in the vertical direction). Besides, the reflection illumination optical system is a cylindrical mirror with scaly conicoid reflection surfaces rather than traditional smooth quadric surface, which can improve the ability to control light, providing a larger angle of uniform illumination. In the later part of this paper, the illumination performance with 8 washing floodlight is simulated, and the illumination performance picture of a real washing floodlight is given.

A theoretical research of fiber laser in single mode operation was presented to evaluate laser targeting characteristics, namely, the directed-energy application. The beam propagation efficiency (BPE) was chosen as the factor to assess the performance of the lasers. Many parameters were studied about their impacts on BPE, including the lens parameters and the transmitting distance. As a result, it was found that the defocus quantity (DQ) valve had a huge impact on directed-energy performance. Given a proper DQ value, the BPE can reach a near limit value. By comparing the BPE performances under different transmission distances, we concluded that when target radius was set to be 5 cm, the ideal state (BPE＞90%) of directed-energy transmission can be achieved within a certain distance of 7 km.

Space-borne integrated path differential absorption (IPDA) lidar for global observation of methane (CH₄) requires a tunable single-longitudinal mode (SLM) pulsed laser source at 1645 nm, which coincides with appropriate absorption line of CH₄ molecules. To meet this application, a pulsed injection-seeded optical parametric oscillator (OPO) using potassium titanyle arsenate (KTA) as the nonlinear crystal is developed. The OPO set-up is a four-mirror stable ring cavity with two pieces of 15-mm-long KTA crystal in critical phase-matching cut for wavelengths around 1645 nm. A single frequency Nd:YAG master oscillator power amplifier (MOPA) laser at 1064 nm serves as the pump. A distributed feedback (DFB) fiber laser with a linewidth of 3 MHz is used for injection of the OPO. To insure successful injection seeding process and enough frequency stability, a cavity-length control method based on the optical heterodyne technique is applied on the OPO cavity. Root-mean-square (RMS) of the frequency variation of the signal pulse compared to the seed laser is measured to be 9.9 MHz, and the Allan deviation is less than 0.25 MHz for averaging time of more than 10 s. With 11 mJ pump pulse input at 50 Hz repetition rate, a signal pulse energy of 1.8 mJ is obtained. The pulse width of this OPO is 15 ns and corresponding linewidth is 45 MHz.

Light is essential for plant growth, affecting plant morphology and physiology. Photovoltaic agriculture (APV) was proposed in the early 80s, but generating electricity on the farm field without influencing the growth of crops has been a challenge for researchers. In this paper, we proposed a newly designed improved photovoltaic agriculture system which can solve this problem optically. Using refraction from groove glass plates, the improved APV system provides crops appropriate light intensity and uniform illumination. We designed the groove glass plate by calculation and simulation. To investigate how different crop grows under different light environments, we examined yield and quality (nutrition) of lettuce under different light conditions. Four different treatments were applied including conventional field environment as the control, conventional APV facility, improved APV system and improved APV system with LED plant fill light lamps. The results indicate that lettuces under the improved APV system had similar yield to the control, and has more than twice the yield of lettuces under the conventional APV facility. In addition, lettuces grown under the improved APV system had a higher nutritional value. These results show that the improved APV system has advantages for wide spread application.

Airborne integrated path differential absorption (IPDA) lidar system is an important instrument to verify the performance and data inversion methods of future space-borne lidar systems for atmospheric CO₂ measurement. A ground vertical path validation experiment of atmospheric CO₂ measurement by an airborne double-pulsed 1.57-μm IPDA lidar has been implemented. The experiment was carried out and temperature, pressure and humidity profiles of Local Meteorological Station at almost the same time are adopted. Backscattering signals from clouds at altitudes of nearly 5 km were received. To avoid the influence of stray light from mirrors, the energy monitoring signal was delayed through the 200 m multimode fiber. But it is interfered by the aerosol scattering echo signals. Inversely, considering the stray light as monitoring signal, the inversion result of XCO₂ is pretty good. Six methods are studied and compared to reduce the bias and improve the CO₂ column-averaged dry-air mixing ratio (XCO₂) accuracy. The “PIM, AVD” and “PIM, AVX” methods are more effective when clouds are acted as hard target. The mean value of lidar measured XCO₂ calculated by “PIM, AVD” and “PIM, AVX” methods is 409.63 ppm. The average value of in-situ instrument UGGA is 411.05 ppm over the same period. The bias between IPDA lidar and UGGA is -1.42 ppm. With averaging 148 shots, the standard deviation of XCO₂ of the IPDA lidar system is 3.68 ppm.

Traditional optical imaging system cannot achieve full field of view and high magnification simultaneously. Enslaved to resolution of detector array, the imaging field vision and magnification cannot be satisfied at the same time. Zoom lens can only vary the magnification for the center field of view, and it is not able to show the large observation field of view and local optical magnified image of either area at one glance. When the focal length of zoom lens reaches the long end, the field of vision will reduce, which leads to missing of marginal targets. The shortage of traditional imaging technique will entail inconvenience. In this paper, we propose a new scheme of geometrical optics imaging system combining two imaging optical path of different focal length in one optical system and the two optical paths image on the same detector array simultaneously. The local optical path can image for arbitrary position of targets and its focal length is variable using liquid lens. The final local variable magnification imaging optical system is shown as example. We offer the detailed design and simulation results, which shows that this kind of optical path configure can image for large field of view and arbitrary local detail at the same sight and maintain acceptable imaging performance.

Imaging optical system with coaxial common aperture near-infrared illumination containing both imaging optical path and illumination light path is established. The imaging optical path is coaxial and shares the front objective lens with the illumination light path. An aspherical short-focus single lens is adopted to decrease the blink surfaces in numbers and simplifies the optical structure. The ghost imaging path is traced backwards to locate the stray light. Absorption region set in the reflector plate eliminates the ghost images induced by the illumination rays reflected by front objective lens surfaces. A uniform rod is adopted to mix the light of near-infrared source, and the reflector plate locates in the conjugate position of aperture stop of both imaging optical path and the illumination light path, which can reduce the impact of occlusion of the reflector plate and ensure the illumination uniformity of the target object. The optical system covers the full field of view of 54° and imaging spectrum range of 450nm to 860nm. We offer the detailed design and simulation results. It shows that this optical system can make good imaging performances and illumination uniformity, and maintain compact structure.