Augmented reality (AR) technology has been applied in various areas, such as large-scale manufacturing, national defense, healthcare, movie and mass media and so on. An important way to realize AR display is using computer-generated hologram (CGH), which is accompanied by low image quality and heavy computing defects. Meanwhile, the diffraction of Liquid Crystal on Silicon (LCoS) has a negative effect on image quality. In this paper, a modified algorithm based on traditional Gerchberg-Saxton (GS) algorithm was proposed to improve the image quality, and new method to establish experimental system was used to broaden field of view (FOV). In the experiment, undesired zero-order diffracted light was eliminated and high definition 2D image was acquired with FOV broadened to 36.1 degree. We have also done some pilot research in 3D reconstruction with tomography algorithm based on Fresnel diffraction. With the same experimental system, experimental results demonstrate the feasibility of 3D reconstruction. These modifications are effective and efficient, and may provide a better solution in AR realization.
Light exerts non-visual effects on a wide range of biological functions and behavior apart from the visual effect. Light can regulate human circadian rhythms, like the secretion of melatonin and cortisol. Light also has influence on body’s physiological parameters, such as blood pressure, heart rate and body temperature. However, human cognitive performance, alertness and mood under different lighting conditions have not been considered thoroughly especially for the complicated visual task like surgical operating procedure. In this paper, an experiment was conducted to investigate the cognition, alertness and mood of healthy participants in a simulated operating room (OR) in the hospital. A LED surgical lamp was used as the light source, which is mixed by three color LEDs (amber, green and blue). The surgical lamp is flexible on both spectrum and intensity. Exposed to different light settings, which are varied from color temperature and luminance, participants were asked to take psychomotor vigilance task (PVT) for alertness measurement, alphabet test for cognitive performance measurement, positive and negative affect schedule (PANAS) for mood measurement. The result showed the participants’ cognitive performance, alertness and mood are related to the color temperature and luminance of the LED light. This research will have a guidance for the surgical lighting environment, which can not only enhance doctors’ efficiency during the operations, but also create a positive and peaceful surgical lighting environment.
Optical tweezers is an increasingly important technique for controlling and probing particles since computer-generated holography (CGH) make steering of multiple traps individually possible. In addition, the dark focus of orbital angular momentum (OAM) beams is increasingly widely used in trapping reflecting, absorbing or low-dielectric-constant objects. In this paper, we present a method to create arbitrary three-dimensional configurations of orbital angular momentum modes to achieve manipulation of micro-particles. Compared with conventional optical tweezers, this method can steer mixed arrays of traps individually and randomly by producing three-dimensional structure of optical vortices. These optical traps we used was formed by a CGH generated complex phase mask, which has three components: 1) a helical phase mask to change the transverse phase structure, 2) a blazed grating phase mask to vary the propagation direction of the incident beams, and 3) a modulated grating phase mask to divert the focal plane from the planar configurations. The latter one ensure that we can form threedimensional trapping patterns. The trap patterns can also be generated dynamically by holographic display system based on liquid crystal on silicon (LCoS). The experimental results show that the refresh frequency of reconfiguring achieves 24fps. Our method is effective and promise an exciting new opportunity to be used as a valuable non-contact manipulation tool in various applications.