Papers by Keyword: Remote Sensor

Abstract: Thermal characters matching optimization of the remote sensor lens materials determinates the thermal adaptive faculty of the sensor, therefore become the most important influencing factor which will decide whether the sensor can work. This paper analyzed profoundly the change of the material’s thermal parameters caused by the working temperature variation, and studied the principles and application of the athermalization manners, whose advantages and disadvantages are also exposited. Formulas are listed to illustrate the principle of the athermatilization which is realized through the reasonable matching of different materials. Design example is represented, athermatilization is achieved through the reasonable matching of optical and mechanical compensation, utilizing the difference of thermal characteristics between different materials, the design and thermo-optical analysis result are also given in the paper, the advantage of the system is the stability in the wide temperature which has no use for groupware to adjust the position of detector .Key words: materials, thermal characters, remote sensor, athermatilization, optical and mechanical compensation

Abstract: This paper presents a method for determining the nature of the material (cool or sterile) running on high-capacity mining belt from basin of Oltenia. When an electromagnetic radiation that propagates in the air meets the separation surface with another environment suffers, among other things, the phenomenon of reflections (diffuse and specula). The intensity of reflected radiation depends on the optical surface properties of the encountered material. On this fact is based the possibility of identification of certain components of the mixture, if the optical properties are considerably different from other components. The method proposed in this paper is based on measuring the reflectance for different regions of the visible and near infrared spectra for samples of coal and sterile, dry and wet. The system for determining the nature of the excavated material mainly consists of an optical head (reflectance sensor) and an ultrasonic head (remote sensor). From experimental observations we see that the reflectance values of coal can be separated from those of sterile, which confirms the possibility of coal detection using the difference in reflectance. The limit of demarcation between reflectance of coal and different types of sterile is influenced by disturbing factors that occur at the plant operating detection under practical conditions such as: material humidity, the variability level of the material on the conveyor belt, the existence of a light background ambient. The method for determining the nature of material (coal or sterile) that circulates on high capacity belts creates real prerequisites of material excavated in conjunction with the possibility of taking quick and effective decisions in the distribution nodes from the coal careers. Key words: electromagnetic radiation, reflectance, coal, remote sensor, detection.

Abstract: A new kind of half integrating sphere radiation system that has the adjustable area of radiating surface in the 380nm-2500nm wave band is introduced in this paper. The opening diameter of the integrating sphere reaches to Φ600mm. Half Integrating sphere radiation system is mainly composed of a half sphere, extension part, cyclic annular baffles and other components. The diameter of half-integrating sphere is Φ1800mm. The radiance uniformity through opening reaches up to 98%. Systems can now be used for all types of large field of view of satellite remote sensor for the calibration of spectral radiance; in addition, it can also be applied for various types of light exposure calibration such as flash lamp and so on.

Abstract: High-precision calibration of space sensors is a complex task. For calibration, integrating sphere system is the main equipment to produce large area uniform radiation source. Such integrating spheres are usually very huge with large diameters, generally more than one meter. Furthermore, such a large integrating sphere costs very high. In order to reduce the size of integrating sphere and cost, the necessary pre-simulation is very necessary. In this paper, a new semi-integrating sphere with 1300mm diameter was designed by using of ray-tracing algorithm on different special structures to improve the design efficiency. The results showed that, 1. The output of semi-integrating sphere system is more sensitive to its inner light source location and the aperture. 2. The practical measurement of semi-integrating sphere is approaching to the simulation findings. Although the opening diameter of semi-integrating sphere reaches to 50% of the diameter of semi-integrating sphere, the output radiance uniformity is still larger than 95% and with better performance.

Abstract: This paper presents an advanced analog-to-digital conversion technique based on a voltage-to-frequency-to-digital conversion that is suitable for remote sensors, telemetry applications and multichannel data acquisition systems. A voltage-to-frequency conversion part can be based, for example, on high performance, charge-balance voltage-to-frequency converter (VFC), where monostable is replaced by a bistable, driven by an external clock, or other existing high performance VFCs. The frequency-to-digital converter “bottleneck” problem in such promised ADC scheme was solved due to proposed advanced method of the dependent count for frequency-to-digital conversion. This ADC technique lets receive many advantages such as high accuracy, relatively low power consumption, low cost solution, wide dynamic range, great stability and faster conversion time in comparison with existing VFC-based techniques. The conversion rate (6.25 µs to 6.25 ms) in such ADC scheme is programmable, non-redundant, shorter than for pulse counting technique and comparable with successive-approximation and Σ- ADC.

Abstract: In this paper, we are presenting a design method and its results for a space optical system with high resolution and wide field of view. This optical system can be used both in infrared and visible configurations. The designing of this system is based on an on-axis three-mirror anastigmatic (TMA) system. Here the on-axis concept allows wide field of view (FOV) enabling a diversity of designs available for the Multi-Object Spectrometer instruments optimized for low scattered and low emissive light. The available FOVs are upto 1º in both spectrum ranges, whereas the available aperture range is F/15 - F/10. The final optical system is a three-mirror telescope with two on-axis and one off-axis segment and its resolution is 0.3m or even lower. The distinguished feature of this design is that it maintains diffraction-limited image at wide wavelengths. The technological developments in the field of computer generated shaping of large-sized optical surface details with diffraction-limited imagery have opened new avenues towards the designing techniques. Such techniques permit us to expand these technological opportunities to fabricate the aspherical off-axis mirrors for a complex configuration.