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光镊技术中,会聚的空心光束形成的能量光阱可用来捕获吸光性颗粒或操纵吸光性颗粒沿光轴方向运动。采用Gerchberg-Saxton(GS)算法计算所需相位,并将相位载入相位型空间光调制器来获得空心光束。为了提高会聚的空心光束能量,对空间光调制器相位屏进行预处理,叠加数字闪耀光栅位相,实现了将四个一级衍射谱闪耀至零级干涉极大位置,空心光束能量提高到原来的4.7倍。为了消除空间光调制器二维光栅结构所形成的零级谱亮斑以及高级谱的影响,在相位屏上加入球面波相位,使得空心光束衍射谱平面与零级谱平面的空间位置分离,并采用带通滤波器将空间光调制器的零级谱亮斑和高级谱滤掉。采用高度会聚透镜将所得空心光束会聚为微米尺寸,可应用于捕获吸光性颗粒。另外,利用离散傅立叶变换的平移原理实现空心光束实时平移,该方法可应用于实时操纵吸光性颗粒移动。
In optical tweezers technology, the converged hollow beam forms an energy light trap that can be used to capture light-absorbing particles or manipulate light-absorbing particles to move along the optical axis. The required phase is calculated using the Gerchberg-Saxton (GS) algorithm and the phase is loaded into the phase spatial light modulator to obtain a hollow beam. In order to increase the energy of the focused hollow beam, the phase mask of the spatial light modulator is preprocessed, the digital blazed grating phase is superimposed, and the four first-order diffraction spectra are shined to the zero-order interference maximum position, and the energy of the hollow beam is increased to the original 4.7 times. In order to eliminate the effect of the zero-order spectral bright spots and the high-order spectra formed by the two-dimensional grating structure of spatial light modulator, the phase of the spherical wave is added to the phase plate so that the spatial position of the diffraction spectrum of the hollow beam is separated from the zero-order spectral plane The bandpass filter is used to filter the spatial light modulator’s zero-order speckle and advanced spectrum. The use of highly converging lenses to condense the resulting hollow beams into micron sizes can be used to capture light absorbing particles. In addition, the real-time translation of the hollow beam is realized by using the shift principle of the discrete Fourier transform, which can be applied to the real-time manipulation of the light absorbing particles.