| dc.description.abstract | This study presents a design for a long-range telescope reconnaissance optical system consisting of one monocentric objective lens and 2,132 sets of identical eyepieces and cameras. The design approach involves using CODE V optical design software to individually design the monocentric objective lens, eyepieces, and cameras, which are subsequently assembled together. Initially, the monocentric objective lens and the eyepieces are combined to form a Kepler telescope system, which is then integrated with the cameras to complete a set of the long-range telescope reconnaissance optical system. The system comprises a larger monocentric spherical objective lens and a set of same eyepieces combined with cameras, hence referred to as the “microcameras.” Therefore, the proposed long-range telescope reconnaissance optical system includes one monocentric objective lens and 2132 sets of microcameras.
The long-range visible light telescope reconnaissance optical system requires the detection of J-20 fighter aircraft at a distance of 125 kilometers, with a target size of 4.69 m × 21.2 m. The detection wavelength ranges from 400 nm to 700 nm, with a field of view of 120° horizontally and 72° vertically, totaling 2132 cameras. The total pixel count is 30.7 gigapixels. The selected CMOS sensor is the MT9F002 from Onsemi, with an active pixel array of 4,384 H × 3,288 V and a pixel size of 1.4 μm × 1.4 μm. The CMOS sensor has a total of 14 MP resolution. Based on the Johnson Criteria, the J-20 fighter aircraft at a distance of 125 kilometers requires 2 line pairs for detection with an accuracy of 95%. The derived total focal length of the optical system is 149.25 mm. Each set of the long-range telescope reconnaissance optical system has a field of view of 2.352° horizontally and 1.764° vertically. The angular resolution per pixel on the CMOS sensor, known as the instantaneous field of view (IFOV), is 9.363 μrad (0.032 arc minutes). The J-20 fighter aircraft at 125 kilometers occupies approximately 169.6 μrad on the CMOS sensor, equivalent to around 18.11 pixels. Compared to the human eye’s resolution of 1 arc minute, the visible light long-range telescope reconnaissance optical system offers a resolution that is 31 times better than what the human eye can see.
After conducting a comparison of various microcamera layouts, it was determined that a hexagonal arrangement offered 1.1547 times better space utilization compared to a square arrangement. Therefore, the hexagonal arrangement was adopted to effectively optimize space efficiency by reducing the spacing between rows and creating a more compact spherical arrangement.
To simulate the conversion efficiency of the long-range visible light telescope reconnaissance optical system in real-world scenarios, a model was created using the optical software LightTools. The maximum solar illuminance was measured using an illuminometer yielding a value of 166,100 lux or 166,100 lm/m^2. With a diameter of 72.447 mm for the first surface of the monocentric spherical objective lens, the incident surface area was calculated to be 1.648 × 10^(-2) m^2. The total luminous flux was 2,738.782 lm, while the actual energy received by the sensor was 998.764 lm, resulting in an average difference of 0.232. Based on these calculations, the conversion efficiency was calculated to be 36.467%.
The design results of this thesis are compared with the AWARE-series gigapixel cameras, which also employs a monocentric multi-scale optical system but with a different purpose. Both systems use the same CMOS sensor, but the main objective of this study is to detect J-20 fighter aircraft at a distance of 125 kilometers. The key difference lies in the overall optical system’s longer focal length in this thesis, resulting in a smaller field of view that allows for finer resolution of the IFOV on a single CMOS sensor. As the detection task includes both the sky and the sea areas, a wider field of view is required for the overall optical system, leading to smaller incident angles and consequently more cameras. This, in turn, increases the total number of pixels in the system. Overall, the optical system designed in this study outperforms the previously designed monocentric multi-scale optical system in the AWARE series. | en_US |