本文選題：儀器　切入點：探測器　出處：《天文學(xué)報》2016年05期 　論文類型：期刊論文

【摘要】：撫仙湖1 m新真空太陽望遠(yuǎn)鏡(New Vacuum Solar Telescope,簡稱NVST)是我國新一代地基太陽觀測設(shè)備之一,其中Hα成像系統(tǒng)是進(jìn)行太陽色球觀測的主要終端.實測Hα觀測數(shù)據(jù)(特別是偏帶觀測數(shù)據(jù))中明顯存在由薄膜干涉引起的等厚條紋,而常規(guī)平場校正有時無法將其消除,并在后期圖像高分辨率重建過程中造成嚴(yán)重影響.為了解決這個問題,利用連續(xù)4 h的Hα偏帶觀測數(shù)據(jù)對干涉條紋的空間和時間分布特性做了分析并發(fā)現(xiàn):干涉條紋的間距或二維空間分布樣式隨時間固定不變,但條紋的強(qiáng)度隨時間變化明顯(4 h左右可見度增加9倍),是導(dǎo)致常規(guī)平場校正無法將其消除的主要原因.由此推斷造成上述時變特性的主要原因是觀測過程中入射光的強(qiáng)度以及入射光與CCD靶面位置的相對角度隨時間發(fā)生了變化,而且產(chǎn)生條紋的薄膜結(jié)構(gòu)與靶面位置距離較近.嘗試了兩種降低條紋可見度的方法.首先對探測器(pco.4000型CCD)光敏介質(zhì)的前封窗進(jìn)行了改造,通過改造前封窗楔角至2?的方案來調(diào)制條紋間距至CCD像元尺度,改造之后小范圍視場內(nèi)可識別出可見度僅為0.6%的少量干涉條紋.其次基于圖像濾波技術(shù)提取干涉條紋圖樣并生成所謂條紋平場,分別采用和比較了頻域傅里葉變換濾波和空域中值濾波兩種方法,結(jié)果基本相同.觀測數(shù)據(jù)再次進(jìn)行條紋平場校正之后,條紋消除效果明顯:可見度可降低8倍左右(即由之前的4.7%降低為0.6%以下).同時也指出多幅圖像的積分(累加)可以有效降低精細(xì)太陽結(jié)構(gòu)在條紋平場提取中的影響,并給出累加時間的經(jīng)驗值約為20 min.
[Abstract]:New Vacuum Solar Telescope1 m vacuum Solar Telescope in Fuxian Lake is one of the new generation of ground-based solar observation equipment in China. The H 偽 imaging system is the main terminal of the solar color sphere observation. There are obvious equal-thickness fringes caused by thin film interference in the observed H 偽 observation data (especially the biased band observation data), which can not be eliminated by conventional flat field correction. In order to solve the problem, The spatial and temporal distribution characteristics of interference fringes are analyzed by using the H 偽 bias band observation data for 4 hours. It is found that the spacing of interference fringes or the spatial distribution patterns of two dimensional interference fringes are fixed with time. However, the intensity of the stripe increases nine times with time, which is the main reason that the conventional flat-field correction can not eliminate it. It is concluded that the main reason for the time-varying characteristics is the input into the observation process. The intensity of the incident light and the relative angle between the incident light and the target surface of CCD vary with time. Two methods to reduce the visibility of the stripe are tried. Firstly, the front sealing window of the detector type CCD-4000) Guang Min is modified, and the front sealing window of the former sealing window is modified to 2? 2 by the transformation of the front sealing window of the film structure which produces the stripes and the location of the target surface is close to that of the target surface, and two methods are tried to reduce the visibility of the stripe. The scheme modulates the fringe spacing to the CCD pixel scale, and after the transformation, a small number of interference fringes whose visibility is only 0.6% can be identified in the small field of view. Secondly, the interference fringe pattern is extracted based on the image filtering technique and the so-called fringe flat field is generated. Fourier transform filtering in frequency domain and median filtering in spatial domain are adopted and compared, respectively, and the results are basically the same. The effect of stripe elimination is obvious: the visibility can be reduced by about 8 times (that is, from the previous 4.7% to less than 0.6%). At the same time, it is pointed out that the integration (accumulation) of multiple images can effectively reduce the influence of fine solar structure on the extraction of the fringe flat field. The empirical value of accumulated time is about 20 mins.
【作者單位】： 中國科學(xué)院云南天文臺;中國科學(xué)院大學(xué);
【基金】：國家自然科學(xué)基金項目(11473064) 中國科學(xué)院基礎(chǔ)局物質(zhì)科學(xué)前沿與交叉項目資助
【分類號】：P111.41

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 彭仁軍,吳健;環(huán)狀干涉條紋成像技術(shù)的實驗研究[J];強(qiáng)激光與粒子束;2003年07期

2 刁其龍;黃春琳;;抑制穿過具有傾斜角度的介質(zhì)探測成像時產(chǎn)生的寄生干涉條紋現(xiàn)象[J];物理學(xué)報;2012年21期

3 鄭中杰;彭青玉;;2.4米望遠(yuǎn)鏡干涉條紋的去除及對測光的影響[J];天文研究與技術(shù);2013年04期

4 尹道先;;透明劈干涉條紋形成的機(jī)理及等厚干涉條紋成立的條件——光學(xué)教學(xué)研究之一[J];內(nèi)蒙古大學(xué)學(xué)報(自然科學(xué)版);1980年01期

5 張祖謀;干涉條紋的光電動態(tài)對準(zhǔn)[J];光學(xué)技術(shù);1981年05期

6 趙國清;;干涉條紋的分析[J];哈爾濱科學(xué)技術(shù)大學(xué)學(xué)報;1981年01期

7 李z靄，

本文編號：1561786