In X-ray absorption fine structure(XAFS) experiments,Soller slits are widely used as filter devices in order to improve the signal to noise ratio.Performing high accuracy manual focusing operations is a time-consuming...In X-ray absorption fine structure(XAFS) experiments,Soller slits are widely used as filter devices in order to improve the signal to noise ratio.Performing high accuracy manual focusing operations is a time-consuming process;therefore,this work introduces an automatic focusing method for Soller slits in multi-element fluorescence detectors.This method establishes a relation model between the fluorescence intensity distribution and the coordinates of the fluorescence excitation point.According to this relation model,the actual coordinates of the fluorescence excitation point can be deduced from the detected fluorescence intensity distribution and used in focusing operations.This method has proven to be feasible in an XAFS experiment at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility.展开更多
Based on the multi-slit method, a new method is introduced to measure the nonlinear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by...Based on the multi-slit method, a new method is introduced to measure the nonlinear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by the multi-slit method. Based on the reconstructed phase space, besides the emittance, the emittance growth from the distortion of the phase space can also be measured. The emittance growth results from the effects of nonlinear force acting on electron, which is very important for the high quality beam in a RF photoinjector.展开更多
随着光学镜头在工业自动化检测领域中的广泛应用,快速且准确地评价镜头的成像质量具有重要意义。为满足这一需求,调制传递函数(Modulation Transfer Function,MTF)测量仪已经得到研发并投入使用。其测量方法主要有垂直狭缝法和倾斜刃边...随着光学镜头在工业自动化检测领域中的广泛应用,快速且准确地评价镜头的成像质量具有重要意义。为满足这一需求,调制传递函数(Modulation Transfer Function,MTF)测量仪已经得到研发并投入使用。其测量方法主要有垂直狭缝法和倾斜刃边法,但垂直狭缝法需保证狭缝与传感器严格对齐,在实际操作难以实现。而倾斜刃边法在测量过程中由于其微分过程导致噪声放大且无法避免,从而影响测量结果。为了应对这些挑战,提出了一种改进的倾斜狭缝法。该方法解决了倾斜刃边法中的噪声放大问题,同时适用于倾斜狭缝的情况,从而实现精确的MTF测量。该方法在去噪方面采用多帧图像像素平均的方法去除随机噪声得到狭缝图;截取图像部分纯背景区域求像素均值作为背景噪声的值,用该图减去该值去除背景噪声。此外,针对此狭缝图引入了一种新的求质心方法。首先以图像的一行或一列的线扩散函数(Line Spread Function,LSF)中最高像素值为中心,遍历其左右像素以确定有效狭缝区域,对此区域数据应用三次样条插值算法,得到亚像素级的质心位置。以当前行或列获得的质心位置为中心,以相机像元尺寸的0.25倍亚像素间距对各像素位置进行离散采样并归档,将沿着狭缝方向对落入同档位的像素值进行均值计算,从而得到4倍超采样的亚像素级线扩散函数。倾斜狭缝法不仅能精确计算狭缝的倾斜角度,而且能精确测量镜头的MTF。对实验中影响MTF测试精度的因素进行了详细分析,结果表明,与国外先进仪器的对比中,该方法在超采样前的奈奎斯特频率以内,MTF值的测量误差小于1%;超采样后,在2.6倍奈奎斯特频率以内,测量误差小于1.3%。实验结果验证了该方法的有效实用性,表明其能够满足工业生产的需求。这一方法的应用可以有效解决购买国外先进MTF测试仪昂贵和难以自主控制的问题。展开更多
基金supported by National Nature Science Foundation of China(No.11175244)
文摘In X-ray absorption fine structure(XAFS) experiments,Soller slits are widely used as filter devices in order to improve the signal to noise ratio.Performing high accuracy manual focusing operations is a time-consuming process;therefore,this work introduces an automatic focusing method for Soller slits in multi-element fluorescence detectors.This method establishes a relation model between the fluorescence intensity distribution and the coordinates of the fluorescence excitation point.According to this relation model,the actual coordinates of the fluorescence excitation point can be deduced from the detected fluorescence intensity distribution and used in focusing operations.This method has proven to be feasible in an XAFS experiment at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility.
基金Project supported by the National Natural Science Foundation of China （Grant No 10347009）.
文摘Based on the multi-slit method, a new method is introduced to measure the nonlinear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by the multi-slit method. Based on the reconstructed phase space, besides the emittance, the emittance growth from the distortion of the phase space can also be measured. The emittance growth results from the effects of nonlinear force acting on electron, which is very important for the high quality beam in a RF photoinjector.
文摘随着光学镜头在工业自动化检测领域中的广泛应用,快速且准确地评价镜头的成像质量具有重要意义。为满足这一需求,调制传递函数(Modulation Transfer Function,MTF)测量仪已经得到研发并投入使用。其测量方法主要有垂直狭缝法和倾斜刃边法,但垂直狭缝法需保证狭缝与传感器严格对齐,在实际操作难以实现。而倾斜刃边法在测量过程中由于其微分过程导致噪声放大且无法避免,从而影响测量结果。为了应对这些挑战,提出了一种改进的倾斜狭缝法。该方法解决了倾斜刃边法中的噪声放大问题,同时适用于倾斜狭缝的情况,从而实现精确的MTF测量。该方法在去噪方面采用多帧图像像素平均的方法去除随机噪声得到狭缝图;截取图像部分纯背景区域求像素均值作为背景噪声的值,用该图减去该值去除背景噪声。此外,针对此狭缝图引入了一种新的求质心方法。首先以图像的一行或一列的线扩散函数(Line Spread Function,LSF)中最高像素值为中心,遍历其左右像素以确定有效狭缝区域,对此区域数据应用三次样条插值算法,得到亚像素级的质心位置。以当前行或列获得的质心位置为中心,以相机像元尺寸的0.25倍亚像素间距对各像素位置进行离散采样并归档,将沿着狭缝方向对落入同档位的像素值进行均值计算,从而得到4倍超采样的亚像素级线扩散函数。倾斜狭缝法不仅能精确计算狭缝的倾斜角度,而且能精确测量镜头的MTF。对实验中影响MTF测试精度的因素进行了详细分析,结果表明,与国外先进仪器的对比中,该方法在超采样前的奈奎斯特频率以内,MTF值的测量误差小于1%;超采样后,在2.6倍奈奎斯特频率以内,测量误差小于1.3%。实验结果验证了该方法的有效实用性,表明其能够满足工业生产的需求。这一方法的应用可以有效解决购买国外先进MTF测试仪昂贵和难以自主控制的问题。
