CAJ | 학술논문

为了利用位相差值法实现大气湍流格林伍德频率的准确测量，研究了位相差值法的有效性、哈特曼探测器采样点数和采样频率的选取方法。首先给出了位相差值法的基本原理和测量噪声去除方法，然后分析了哈特曼探测器采样点数和格林伍德频率的统计平均次数对测量精度的影响，结果显示，当采样点数大于400、统计平均次数大于400时，可以实现大气湍流格林伍德频率的准确测量。研究了测量噪声的影响，结果表明：去除噪声后，测量值的偏离误差从30％降低到0.6％。研究了算法的重复性精度，得到测量值偏离量的RMS值为1.9 Hz，占理论值的3％，说明测量方法非常稳定。依据上述结果，对8～108 Hz的湍流进行测量和分析，结果显示，当不考虑空气扰动时，测量值与理论值基本一致。最后，研究了哈特曼探测器采样频率和格林伍德频率之间的关系：哈特曼探测器的采样频率越高，能够准确测量的格林伍德频率也越高，并得到了定量的经验公式。上述结果表明，在满足采样点数、采样频率以及统计平均次数等条件下，位相差值法可以实现大气湍流格林伍德频率的准确测量。该研究工作为大气湍流的格林伍德频率测量提供了应用依据。
위료이용위상차치법실현대기단류격림오덕빈솔적준학측량，연구료위상차치법적유효성、합특만탐측기채양점수화채양빈솔적선취방법。수선급출료위상차치법적기본원리화측량조성거제방법，연후분석료합특만탐측기채양점수화격림오덕빈솔적통계평균차수대측량정도적영향，결과현시，당채양점수대우400、통계평균차수대우400시，가이실현대기단류격림오덕빈솔적준학측량。연구료측량조성적영향，결과표명：거제조성후，측량치적편리오차종30％강저도0.6％。연구료산법적중복성정도，득도측량치편리량적RMS치위1.9 Hz，점이론치적3％，설명측량방법비상은정。의거상술결과，대8～108 Hz적단류진행측량화분석，결과현시，당불고필공기우동시，측량치여이론치기본일치。최후，연구료합특만탐측기채양빈솔화격림오덕빈솔지간적관계：합특만탐측기적채양빈솔월고，능구준학측량적격림오덕빈솔야월고，병득도료정량적경험공식。상술결과표명，재만족채양점수、채양빈솔이급통계평균차수등조건하，위상차치법가이실현대기단류격림오덕빈솔적준학측량。해연구공작위대기단류적격림오덕빈솔측량제공료응용의거。
To measure the Greenwood frequency of the atmospheric turbulence accurately , the validity of phase difference method and the selection of the sampling points and the sampling frequency of the Shack -Hartmann wavefront sensor ( S-H WFS) have been studied .Firstly, the principle of the phase difference meth-od and the noise elimination algorithm are given .Secondly , the effects of the sampling points of S-H WFS and the statistical times of Greenwood frequency on the measurement accuracy are investigated .The experimental results show that , while both the sampling points and the statistical times are more than 400 , the Greenwood frequency can be measured accurately .Thirdly, the influence of the measurement noise is considered and the result shows that the deviation error of the measured value is reduced from 30% to 0.6% with the noise re-moved.Fourthly, the repeatability of the phase difference method is measured .It is shown that the deviation RMS error is 1.9 Hz which is 3% of the ideal value.Therefore, the Greenwood frequency can be measured accurately with the phase difference method .Based on the above results , the Greenwood frequency of the at-mospheric turbulence is measured and analyzed with the range of 8-108 Hz.It indicates that the measured value is almost the same as theoretical value without consideration of the disturbance of the air in the Lab .At last , the relation between the sampling frequency of S-H WFS and the Greenwood frequency is investigated .It can be seen that the sampling frequency of the S-H WFS should be increased if the measured Greenwood fre-quency is enlarged .Furthermore, an empirical formula is achieved to calculate the needed sampling frequency of the S-H WFS.In a word, all the results show that , when it meets the demand of sampling points , sampling frequency and statistical times , the phase difference method can be used to measure the Greenwood frequency of atmospheric turbulence accurately .