Method to measure the phase modulation characteristics of a liquid crystal spatial light modulator

Abstract

The universal liquid crystal spatial light modulator (LC-SLM) is widely used in many aspects of optical studies. The working principles and applications of LC-SLM were introduced briefly. The traditional Twyman-Green interference method, which was used to measure the phase modulation characteristics of a liquid spatial light modulator, had some obvious disadvantages in practice. To avoid these issues, the traditional Twyman-Green interference method was improved. Also, a new method to process interference fringes and measure the shift distances and cycles automatically by computers was proposed. The phase modulation characteristics of P512-1064 LC-SLM produced by the Meadowlark Company were measured to verify the validity of the newly proposed method. In addition, in order to compensate and correct the nonlinear characteristics of the phase modulation curve, three universal inverse interpolation methods were utilized. The root mean squared error and residual sum of squares between the calibrated phase modulation curve and the ideal phase modulation curve were reduced obviously by taking advantage of the inverse interpolation methods. Subsequently, the method of shape-preserving subsection cubic interpolation had acquired the best performance with high computation efficiency. Experiments have been performed to verify the validity of the interpolation method. The experimental results showed that the phase modulation characteristics of LC-LSM could be acquired and calibrated automatically with convenience and high efficiency by utilizing the newly proposed processing method.

High Precision Optical Wavefront Generation Using Liquid Crystal Spatial Light Modulator (LC-SLM)

“…In general, the measurement methods of phase modulation characteristics can be divided into two groups-the interference method and the diffraction method. Among them, interferometry mainly includes double-slit/hole interferometry [5][6][7], Twyman-Green interferometry [8][9][10][11], Mach-Zehnder interferometry [12][13][14], and digital holographic interferometry [15][16][17]. The measurement of phase modulation characteristics of interferometry mainly depends on the displacement of fringe pattern, but the two beams have to travel a long path in the air before the interference, and the mechanical vibration, air turbulence, and other environmental factors will cause the change of their optical path difference, resulting in a large fluctuation in the acquisition of fringe pattern.…”

Optimising of the material and laser parameters for high-power laser spatial beam smoothing based on stimulated Brillouin scattering

“…Optimising of the material and laser parameters for high-power laser spatial beam smoothing based on stimulated Brillouin scattering Xuehua Zhu 1,2 , Huicheng Yang 1,2 , Guanling Wang 1,2 , Daohua Wu 1,2 and Yueyou Qiu 1,2 high-power laser system. However, using SLM for laser spatial beam smoothing has an inherent disadvantage of low transmittance [7]. Although a high beam quality can be achieved by using this method, it may happen at the expense of the output energy.…”

Spatiotemporal shaping of high power laser pulses based on stimulated brillouin scattering

“…In the past decades, laser system engineering has accumulated several techniques to avoid excessive spatial modulation by using liquid crystal spatial light modulators (SLMs) [5][6][7], random phase plates [8], far-field spatial filter [9], and so on. Randomized phase plates is randomly arranged by hundreds of small units with 0 or π phase delay, and the far-field smoothing is realized through the superposition of diffraction of each unit.…”

“…SLM is an active programmable beam shaping device, which can pre-compensate the non-uniformity of laser beam profile by adjusting the transmissivity of each pixel, with good results. However, the total transmissivity of SLM devices is relatively low [7], and the beam quality is improved at the cost of the output energy. In our previous research, we proposed a more effective method based on SBS to enhance laser near-field uniformity with high energy transmittance [10,11].…”