2012 Vol. 5, No. 4
Some optical methods for non-invasive blood glucose monitoring are introduced, and the advantages of infrared spectroscopy applied to the non-invasive blood glucose monitoring are presented. The main problems of infrared spectroscopy in the non-invasive blood glucose monitoring are analyzed, including complicated transmission of light in tissue, weak absorption signal of glucose, overlapped absorption spectra of different biochemistry components, serious interference of background absorption and so on. Recent advances of infrared spectroscopy in non-invasive blood glucose monitoring are summarized and the methods to restrain the interference of background absorption are pointed out. It suggests that the tissue fluid can replace the blood applied to the measurement of blood glucose. Finally, the paper gives further research trends of this field, which includes describing the transmission of light in tissue accurately, measuring the spectra of epidermis or the superficial layer between epidermis and dermis, improving instrument SNR, and building the calibration model for the absorption band of blood glucose.
The developing status of large aperture ground-based telescopes is reviewed in this paper. The significance of bigger apertures for telescopes and their main technological approaches are expatiated and the summary on appliance values of modern large aperture telescopes is given. Then, it introduces five kinds of modern typical large telescope systems, which represent the topmost technological level. The key structures and technologies of large telescopes about mount, telescope tubes, primary mirror supports and secondary mirror assemblies are disscussed. Finally, it summarizes the developing trends of the large aperture ground-based telescopes and points out that some of the optical systems in the telescopes have been changed from coaxial systems to off-axial systems, while they are better application prospects.
Wavefront correctors are the key components of the adaptive optical systems and the techniques to fabricate wavefront correctors have been developed for many years. This paper introduces several kinds of wavefrom correctors that are commonly used in adaptive optical systems, such as the deformable mirror with discrete actuators and continuous faceplate, segmented deformable mirror, membrane deformable mirror, bimorph deformable mirror, MEMS deformable mirror, liquid crystal corrector and the adaptive secondary mirror. The realization methods of the wavefront correctors and their working principles are presented in detail, and the performance, the number of degrees of freedom and the speed of response are compared. Finally, it summarizes the technology innovations and development trends of the wavefront correctors in the new applications.
This paper summarizes the technological states of high power anti-missile laser weapons, including the composition, technological difficulty and the developing directions of ground-based anti-missile laser weapons and airborne anti-missile laser guiding weapons in the aerial defence. It also introduces the composition and the function of the heaven base and space base anti-missile laser weapons and analyses the main technologic capability and the key technology of the anti-missile laser weapons in the aerial defence.
The influence of vibration angles and vibration angle velocities caused by the dynamic imbalance disturbing torques of a rotor for the Single Gimbal Control Moment Gyro on the TDI CCD camera imaging is analyzed. By coordinate transformation, the disturbance torque is transformed from a rotor coordinate to a satellite coordinate, and then satellite attitude dynamics equations are used to calculate the vibration angular displacements and vibration velocities of stars in an image motion compensation model of the TDI CCD camera. TDI CCD camera simulation system with the material point corresponding to imaging point model is used to analyze the imaging MTF and mutual correlation similarity measure. Experiments show that when SGCMG rotor speed rotates at 3 000 r/min, the MTF horizontal shift is 0.997 and mutual correlation similarity measure is 0.996 1; When SGCMG rotor speed rotates at 6 000 r/min, the MTF horizontal shift is 0.928 3, mutual correlation similarity measure is 0.974 8. The results prove that the quality of TDI CCD scanning images is terribly influenced by vibration angles and angle velocities caused by the dynamic imbalance of the SGCMG rotor. It must carry a damping when the SGCMG is used.
As the geometric precision of a three-line array CCD tridimensional mapping camera is one of the important factors to affect the mapping precision, the assembly method for the mapping camera is studied to build and ensure the spatial geometry relation of the mapping cameras. Firstly, the structure of mapping camera system and the definition of the coordinate are introduced. Then, the assembly requirements of the basal mirrors and the mapping camera are brought out. Finally, the assembly process of the mapping camera is determined, and its assembly steps are significantly introduced. After the camera alignment, the results show that the Optical Transfer Function(OTF) of the mapping camera is more than 0.2, and its distortion is less than 0.03%. Moreover, the space position relation among cameras can meet the installing requirements. The method can satisfy the alignment requirements of space geometry precision of the three-line array CCD tridimensional mapping camera.
Based on the requirements of mapping cameras for imaging quality and the stability of inner orientation elements, the characteristics of three focusing strategies are analyzed in detail, and the strategy which is most suitable for the mapping cameras is confirmed. A ball screw driving linear-guide-type focusing mechanism is designed, and its focusing sensitivity is calculated to be 0.2 m. Precision testing and test validation are performed, which shows that the pointing accuracy of the focusing mechanism is superior to 2 and the positioning accuracy of the focusing mechanism is better than 3 m. Test results demonstrate that the designed focusing mechanism has the characteristics of compact structure, high stiffness and high displacement precision and it can meet the focusing requirements of off-axis TMA mapping cameras.
An optical system for Fizeau-type synthetic aperture telescopes is designed by using three subapertures with small diameters to obtain the high resolution of an equivalent large aperture. First, considering both u-v covering of sparse frequency and structure simpleness, the Golay-3 array is choosen to be the subaperture arrangement and the filling factor F is 0.44. Then, according to the character of optical system configuration, the optical system is divided into the subapertures, ray controller and the ray combiner to be designed, respectively. The configuration of afocal subaperture is Cassegrain type with achromatic double lenses rearward, and its pupil diameter, Field of View(FOV) and angle magnification are 300 mm, 0.2 and 10, respectively. Moreover, the ray combiner is composed of 5 pieces of glass including high refractive index glass and special partial dispersion glass, and its focal length is 600 mm, F-number and FOV are 6 and 2. The Point Spread Function(PSF) and Modulation Transfer Function(MTF) of the subaperture are analysed, and the results show that the equivalent diameter of total system is 1.89 times that of the subaperture, and the angular resolution of total system is 0.24.
In consideration of the defects of traditional condenser systems in low condensing rates, high costs and complex structures, high-power solar condensers were studied and designed. Based on the advantages of Cassegrain structure in high light gathering and beam coupling, a new type of high-power solar condenser was designed, and the optical design software ZEMAX was used to simulate the structure in different incident angles. The simulation results show that the Cassegrain structure eliminates the impact of spherical aberration. When arrival angle of sunshine is 0.5?, a concentration ratio of 544 and an optical efficiency of 84.835% can be obtained. Compared with traditional condenser systems, this device has a simple structure, high optical efficiency and a low cost. It has opened up a new path for the commercialization of solar condensers.
Due to the large numbers of lenses, it is impossible for the complex refractive system to use a compensator only to compensate the corresponding misalignment. Based on the aided alignment technology, this paper proposed a method to reduce the range of compensator selection by building a sensitivity matrix and finding the internal relations between decenter disalignments and tip/tilt ones. Then, a method by using only four compensators to compensate the whole optical system was proposed by analyzing the sensitivities of misalignments, and the feasibility of the selected compensators was proved by a simulation. After finishing assembling of the whole optical system, the tested wave front errors were induced into the sensitivity matrix in the form of 36 items of Fringe Zernike polynomials to calculate the values and the moving directions of compensators driven by precision actuators. The test results show that the wave front errors(RMS) have reduced to 25.993 nm from 50.864 nm, which is better than the qualifications and proves that the selected four compensators are right and effective.
The diaphragm structure in a lithographic projection objective is designed depending on the character demand for large adjustable ranges, small installing spaces and high adjustable precision, and the iris diaphragm has an aperture of 236 mm and adjustable precision of NA?0.003. The parameters of the iris piece are calculated in detail and the size of part is acquired. Then, the part of gear is used to reduce the mass and motion friction of the motion structure and the strength of parts such as the rivet and gears is checked to ensure the adjustable precision and material stress of the diaphragm. It is shown that the stress of all of key parts of the diaphragm meets the requirement of the system and the nature frequency of the diaphragm is no dense frequency phenomenon. These results prove the rationality of the proposed structure.
To speed up the convergence rate of Stochastic Parallel Gradient Descent(SPGD) algorithm that was used to control a deformable mirror for wavefront shaping and to enhance the capability of real-time wave-front shaping, a simulation model was established by using wave-front distortion described by 12 Zernike polynomials and a 32-unit deformable mirror. Two constant matrixes were obtained with the orthogonality of Zernike polynomials in a unit circle, which simplizes computations and speeds up the running time of the algorithm. After 660 iterations, the Strehl ratio is 0.8. Comparison results of 6 kinds of SPGD algorithms with Matlab7.8.0 show that indirect-fixed-bilateral SPGD algorithm can be used in the conditions of low Strehl ratio, and indirect-varied-bilateral SPGD algorithm can be used in the conditions of high Strehl ratio, which will speed up the convergence rate of SPGD algorithm and provide the theoretical guidance for laser shaping.
To trigger the rotated spark switch in a CO2 laser stably and reliably, a high-voltage pulse trigger system is designed and a new method for driving and protecting Insulated Gate Bipolar Transistor(IGBT) is proposed. According to the trigger structure of rotated spark switch in the CO2 laser, a pulsed source which can output 100-500 Hz repetition-rate pulses and a single pulse is developed with the EPM3512 CPLD chip and the IGBT drive circuit with over-current, over-voltage protection and Electromagnetic Compatibility(EMC) design is proposed by a optocoupler HCPL-3120. Besides, the model of a high-voltage pulse transformer is simulated by PSPICE software. Finally, an experimental platform is buit to test the system performance online. Experimental results indicate that the high-voltage pulse trigger system can output high-repetition-rate pulses higher than 38 kV continuously and stably, which satisfies the requirements of the rotated spark switch in the CO2 laser for stability and reliability.
To research the space optical remote sensing quantitatively and to improve the measuring accuracy of detectors in UV region, this paper analyzes the radiation calibration of the detectors and provides a standard transferring method. The working principle, establishing standard and the development status of UV detector standard-cryogenics radiometers are introduced in detail. Then, the selecting and the procedure of standard transmission of the transfer standard detector in Nation Institute of Standards and Technology(NIST) are discussed in-depth. The experimental results provide the theoretical foundation for the research on the detector calibration method and give the guidance for using the standard detector method to improve the calibration accuracy and accelerateing engineering application.
The Electromagnetically Induced Transparency(EIT) in crystals doped with rare-earth ions was researched. By taking a Er3+: YAG crystal for a sample, the probe field absorption as a function of the concentration of Er3+ ions was calculated by using density matrix equations in rotating-wave approximation. It indicates that when the detuning of the probe field p is 0, the transparency window of a probe field is generated, which demonstrates the feasibility to achieve the EIT in crystals doped with rare-earth ions. Furthermore, an excitation scheme for Pr3+: Y2SiO5 was performed, and it experimentally exhibits that when the temperature is 6 K, a 100% transparency window in the resonant absorption peak is formed in the absorption spectrum of Pr3+: Y2SiO5, and the EIT phenomenon in crystals doped with rare-earth ions is realized. In addition, the dependence of temperature and coupling field detuning on the EIT was presented. It is found that when the temperature increases to 15 K, the transparency window disappears, while the detuning of coupling field becomes larger and the transparency window gets smaller.
A long-range order wrinkle pattern is fabricated based on Polymerized Poly(Ethylene Glycol)-Diacrylate(PEGDA). The formation mechanism and adjustment method are studied. The large scale of cycle pattern array occurs in the surface of polymeric hydrogel according to adjusting the optical interaction processing parameters. The dimension of the pattern can be adjusted from 101-103 m and the area of whole pattern can be an order of magnitude in millimetre or centimetre. It demonstrates that the unique performance is from the competition of the bending of skin and the compressing of bulk in the PEGDA hydrogel film.