In this paper, it presents a new imaging technology that could realize to extent the depth of field and contribute to receive the large iris aperture optical system. The new technology combines lenses assistance and the aberration modulation. Based on the method, we establish a new optical system. Simulation results indicate that the modulation transfer function (MTF) curves of this optical system have consistency feature during different object distances. According to the feature, we can restore ambiguous images to unambiguous ones. Compared with another normal optical system, the experimental results indicate that the new optical system has the large depth of field and large iris aperture features.
Terahertz(THz) wave modulator technology, due to its important value of imaging and detecting research. In the paper, we discuss the Polyethylene lens based the terahertz wave front modulation, which is benefit the terahertz wave image technology. Simulation results show that the optical system can extent the depth of imaging field of test objects based on continuous terahertz source. The way to get the image has significant meaning for detection and large image quality.
Compared with the wide application of liquid crystals (LCs) in the visible frequency band, their properties in the
terahertz band have not been investigated extensively yet. In this paper, we have investigated the optical anisotropy of
LCs TEB30A and 9023 at room temperature using terahertz time-domain spectroscopy (THz-TDS). The extraordinary
and ordinary refraction indices of LC TEB30A are ne≈1.84 and no≈1.65, or a birefringence of 0.19 from 0.5 to 2.2
THz. The extraordinary and ordinary refraction indices of LC 9023 are ne≈1.83 and no≈1.62, or a birefringence of
0.21 from 0.5 to 2.2 THz. LC 9023 exhibits a little larger terahertz birefringence than that of LC TEB30A.
The Reverse Hartmann test is developed rapidly, robustly, and accurately in measuring precision aspheric surface. The onaxis
design provides better control of the astigmatism in the test. We use an on-axis Hartmann test in reverse to measure
the aspheric optical mirrors. In the configuration, the LCD with a light pattern on the screen illuminates to the tested surface,
and a 2μm-thick pellicle beam splitter is employed to obtain the coaxial light model. An optical flat with 1/20λ surface
precision is used to calibrate the rays which pass through the external pinhole and image at the detector, and the data are
processed to obtain the direction vectors of arbitrary reflected rays. The surface gradients are determined by the spatial
equations of incident and reflected rays which have been calibrated. The shape of surface is finally reconstructed by
Zernike polynomial fitting. The experiments include measuring a 76.2mm off-axis parabolic mirror and a 76.2mm
spherical mirror. The experimental results show coaxial reverse Hartmann test system may allow for accurate
measurements with uncertainties in the micrometer range using cost-effective equipments.
In recent years heart and blood vessel diseases kill more people than everything else combined. The daily test of heart rate for the prevention and treatment of the heart head blood-vessel disease has the vital significance. In order to adapt the transformation of medical model and solve the low accuracy problem of the traditional method of heart rate measuring, we present a new method to monitor heart rate in this paper. The heart rate detection is designed for daily heart rate detection .The heart rate signal is collected by the heart rate sensor. The signal through signal processing circuits converts into sine wave and square wave in turn. And then the signal is transmitted to the computer by data collection card. Finally, we use LABVIEW and MATLAB to show the heart rate wave and calculate the heart rate. By doing contrast experiment with medical heart rate product, experimental results show that the system can realize rapidly and accurately measure the heart rate value. A measurement can be completed within 10 seconds and the error is less than 3beat/min. And the result shows that the method in this paper has a strong anti-interference ability. It can effectively suppress the movement interference. Beyond that the result is insensitive to light.
According to the aero-thermal effects and aero-thermal radiation effects of the optical window, the thermo-optic effect, the elasto-optical effect and the thermal deformation of the optical window are analyzed using finite element analysis method. Also, the peak value and its location of the point spread function, which is caused by the thermo-optic effect and the dome thermal deformation, are calculated with the variance of time. Furthermore, the temperature gradient influence to the transmission of optical window, the variation trend of transmission as well as optical window radiation with time are studied based on temperature distribution analysis. The simulations results show that: When the incident light is perpendicular to the optical window, image shift is mainly caused by its thermal deformation, and the value of image shift is very small. Image shift is determined only by the angle of the incident light. With a certain incident angle, image shift is not affected by the gradient refractive index change. The optical window transmission is mainly affected by temperature gradient and thus not neglectable to image quality. Therefore, the selection of window cooling methods, needs not only consider the window temperature but try to eliminate the temperature gradient. When calculating the thermal radiation, the optical window should be regarded as volume radiation source instead of surface radiator. The results provide the basis for the optical window design, material selection and the later image processing.
In recent years, morbidity and mortality of the cardiovascular or cerebrovascular disease, which threaten human health greatly, increased year by year. Heart rate is an important index of these diseases. To address this status, the paper puts forward a kind of simple structure, easy operation, suitable for large populations of daily monitoring non-contact heart rate measurement. In the method we use imaging equipment video sensitive areas. The changes of light intensity reflected through the image grayscale average. The light change is caused by changes in blood volume. We video the people face which include the sensitive areas (ROI), and use high-speed processing circuit to save the video as AVI format into memory. After processing the whole video of a period of time, we draw curve of each color channel with frame number as horizontal axis. Then get heart rate from the curve. We use independent component analysis (ICA) to restrain noise of sports interference, realized the accurate extraction of heart rate signal under the motion state. We design an algorithm, based on high-speed processing circuit, for face recognition and tracking to automatically get face region. We do grayscale average processing to the recognized image, get RGB three grayscale curves, and extract a clearer pulse wave curves through independent component analysis, and then we get the heart rate under the motion state. At last, by means of compare our system with Fingertip Pulse Oximeter, result show the system can realize a more accurate measurement, the error is less than 3 pats per minute.
One of the most crucial techniques of laser warning system is to acquire the direction information from the
laser threat. According to the low resolution of laser warning system with imaging mode, a new method for measuring
laser incident direction which possessed higher resolution was proposed. This novel method was based on cylindrical
lens group and linear IRFPA, and the laser incident direction was achieved by offset of line spot. It not only deduced the
direction formulas, but also analyzed the resolution of measuring laser incident direction in detail. The simulation result
shows that the FOV of this new kind of laser warning system could achieve ±16°; the azimuth resolution is up to 0.52°
and pitch resolution is up to 0.017°; the resolution increases with incident angle. In addition, an experiment with visible
light, single cylindrical lens, linear array CCD was done to verify this method and its advantage on resolution. The
analysis of laser incident orientation resolution is significant to select suitable parameter of detector and demonstrate
orientation resolution of system.
Sun is used as light source for spectrum analysis of atmosphere material with sunlight through atmosphere. The stronger
sunlight enters the detector, the more accuracy can be achieved. However, due to the inhomogeneity of the atmosphere,
the gray image of sun is not only irregular, even the interference of clouds will divide sun into different parts. Thus,
when the light intensity, shape and location of sun in the image keep changing, it is critical for obtaining and following
the position of the strongest sunlight accurately. In the paper, a novel method of sun scene simulation for observation of
the sun through the atmosphere is presented. The method based on the active optical control system, is used in sun scene
simulation with the variation of light intensity, shape and position. The method has a simple theory and is easy to be
realized. This simulation system composing with computer, projection devices, micro deformable mirror and the optical
lens group can be used for simulating optical properties of atmosphere with different density, humidity, and air flow rate,
for ensuring the accuracy and real-time sun scene simulation.
A method for capturing the solar shape and location on occurrence of solar occultation is presented. On occurrence of
occultation when the Sun is covered by atmosphere, the solar shape viewed by satellite-borne detector on certain orbit
through atmosphere at different heights varies greatly due to such factor as the in homogeneity of atmosphere and cloud
covering, etc. During the varying of heights of atmosphere, the gray image of Sun also changes, which even appears
several parts in different size due to the disturbance of cloud layer. Based on which, the Paper proposes a method for
capturing solar shape and intensity on occurrence of solar occultation. First, taking the solar grey image without
atmospheric refraction effects as a reference; then the refraction angle of Sun ray after being refracted by atmosphere can
be reversely calculated by using Abel integral function and the vertically distributed data of index of refraction; Last, the
solar shape after passing atmosphere can be obtained by calculating the refraction angle of the ray on solar limb. We
have obtained the image of solar shape and intensity at the occultation central point of contact from 5km to 60km when
the detector is located at the defined satellite orbit (600km) by simulation. This method is of great significance for
realizing the solar simulator which can reflect solar shape and intensity in a comparatively truly degree under the
circumstance of existing various affecting factors for application in the fields like measuring and calibration of posture
parts of satellite, remote sensing technology and material measure, etc.