製作登陸小行星用的Scheimpflug相機系統;Prototype of Scheimpflug Camera System for Asteroid Lander

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Title:	製作登陸小行星用的Scheimpflug相機系統;Prototype of Scheimpflug Camera System for Asteroid Lander
Authors:	楊哲明;Yang, Zhe-Ming
Contributors:	太空科學研究所
Keywords:	Scheimpflug鏡頭;SD卡UHS-I模式;印刷電路板布局;FPGA;景深;光學傳遞函數;調制傳遞函數;Scheimpflug Lens;SD card UHS-I mode;PCB layout;FPGA;Depth of field;Optical transfer function;Modulation transfer function
Date:	2020-07-30
Issue Date:	2020-09-02 15:24:57 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文計畫設計登陸小行星太空船上的科學酬載，用來進行地表觀測的相機系統。此相機系統，包含全景深(Scheimpflug) 的前置鏡頭，太空規格的WatecT065影像感測器以及抗輻射的高速影像擷取系統，其中全景深的前置鏡頭將應用於太空船著陸後，進行小行星地表從近到遠的清晰拍攝。高速影像擷取系統使用SmartFusion2 SOM M2S025FG484I做為核心進行影像資料擷取以及處理，並且以SD 卡的UHSI模式儲存到Micro SD 卡中。本論文根據Scheimpflug 的光學設計，使用H1214FICS3 成像鏡頭進行科學雛形實驗，驗證Scheimpflug 原理。證明即使使用一般成像鏡頭，也能達到全景深，距離為119.53mm 到363.71mm 之間；MTF(Modulation Transfer Function) 在此鏡頭中心的全頻空間頻率55cycles/mm 以內仍能達到30% 的對比。若採用光學設計優化的鏡頭，鏡頭中心理論上的MTF 可以達100cycles/mm。另外研究上開發WatecT065影像感測器的高速影像擷取系統，採用Micro SD 卡進行資料的儲存。為克服Micro SD 卡資料儲存速度太慢的問題，研究上使用UHSI模式，將原本SPI 的資料寫入速度提升數百倍，規格上的時脈速度可從100kHz∼ 400kHz 提升到208MHz。實驗驗證了SPI 模式可以進行讀寫，SD 模式也可以只靠硬體設計來初始化，希望改善立方衛星使用Micro SD 卡進行資料的儲存而速度過慢的問題。影像資料使用了邏輯分析儀驗證SmartFusion2 SOM M2S025FG484I的過濾資料功能，證實了此高速影像擷取系統可行性。實驗後續以LabVIEW 改善了自動化的量測速度，協助量測此鏡頭的MTF，以及WatecT065 的響應度。本論文設計全景深的相機系統的科學酬形體，希望能應用於對地球或人造衛星產生危害的小行星—99942 Apophis，預計2029 年會靠近地球，距離地球表面31,000 公里。當小行星太空船成功登陸小行星表面並能成功拍攝影像之後，本論文設計全景深觀測小行星表面結構的相機系統也可用於未來的月球探測艇上。 ;The primary purpose of this thesis is to design a scientific prototype of a camera system for the observations of the asteroid surface and the preparation for landing on the asteroid. Our designed camera system consists of the Scheimpflug front lens system, space-qualified WATEC—T065 CCD, and radiation-hardened high-speed image capture system. After landing on the asteroid, the Scheimpflug front lens system is designed to be tilted with respect to the image plane and to take panoramic photography from near to the far edge of the asteroid surface. The high-speed image capture system processes the image data and stores into the Micro SD card by UHS-I mode. According to the design rule of Scheimpflug principle, we utilize the commercial lens system (Computar H1214FICS3) to verifying the Scheimpflug principle in the experiment. We concluded that the H1214FICS3 could also achieve the performance of deep focus in the near region (from 119.53mm to 363.71mm). The MTF of the center of the H1214FICS3 can be 30\% contrast within 55cycles/mm. Using Code V with optimization, the MTF at the center of our designed lens system can be 30\% contrast within 100cycles/mm. We also improve the WATEC—T065 high-speed image capture system by choosing the UHS—I mode of Micro SD card to enhance the storage rate in comparison with typical SPI mode of Micro SD card. In the experiment, we verified SPI mode for reading and writing data, and SD mode for initialization only with FPGA design. The image data are verified by Logical Analyzer. Theoretically, the UHS—I mode can run 100 times as fast as the SPI mode. Ours adopted UHS—I mode increases the Micro SD card data storage rate, especially for the application of current CubeSat. Besides, we improved the measurement speed of the measurement of MTF and the responsivity of lenses by coding LabVIEW applications. Our designed camera system for asteroid lander is planned to observe the potentially hazardous asteroids - 99942 Apophis, which will approach Earth in 2029, and is also applied for observing the lunar surface for future Moon Lander.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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