Spatial Light Modulator (SLM) is a powerful active optical component to change the optical wavefront by electrical signal and had been widely investigated for many applications. We use LCoS (Liquid Crystal on Silicon) which has high reflectivity and spatial resolution as main component of SLM educational kit, and present a series of experiment to let students know the background theory of SLM. Our course mainly has three parts, the first part is the principle of LCoS SLM which has polarization, jones matrix, and uniaxial crystal theory. The second part is wave optics which can see interference, diffraction, and dispersion phenomenon. The last part is Fourier optics which has the concept of spatial frequency, spectrum, Fresnel diffraction, and Fraunhofer diffraction. This educational kit also includes software that produces some basic diffraction grating which dynamically response to parameter changing and customized user's own diffraction grating by macro commands. In this paper we will describe the background theory, experiments design, and result of experiments to show what students can learn from the SLM educational kit.
For focusing the elliptical Gaussian beam directly, the effects of a non-circular aperture on the focusing properties are studied. The focusing properties for different shapes of apertures, which include a circle, an ellipse and a rectangle, are calculated and compared. Moreover, for different elliptical Gaussian beams, an empirical aperture selection rule that can be used to circularize the focusing spot is proposed. The energy transmission ratios are also considered in this paper.
For focusing the elliptical Gaussian beam directly, the e ects of a non-circular aperture on the focusing properties are studied. The focusing properties for di erent shapes of apertures, which include a circle, an ellipse and a rectangle, are calculated and compared. Moreover, for di erent elliptical Gaussian beams, an empirical aperture selection rule that can be used to circularize the focusing spot is proposed. The energy transmission ratios are also considered in this paper. Gaussian beams. In practical applications, there are two methods of focusing elliptical Gaussian beams. The ®rst method, which is most often used, is to use prisms or cylindrical lenses [1] to obtain a circular beam before focusing. Because of misalignment and defects of the optical elements this approach may cause unavoidable throughput losses and increase the system cost. The other method is the so-called direct focusing method, which utilizes the aperture to truncate the incident beam to get the desired characteristics of the focusing spot. Marchant [2] studied the direct focusing properties of the elliptical Gaussian beams by using the central irradiance and the line spread function. With considerations of system cost and power increase of the laser diode, Kondo [3] has used this approach for the optical heads. However, when the elliptical beam can be focused through a circular objective lens, the focusing spot will also be non-circular, and the ellipticity of the focusing spot depends on the beam ellipticity and the apodization values [2]. Kondo [3] showed that the orientation of the major or minor axis of the elliptical Gaussian beam can a ect the signal level, the spatial frequency characteristics and the cross-talk level. In some other applications, for instance the laser printer, a non-circular focusing spot is an annoying problem.According to the di raction theory, the shape of the aperture can a ect the di raction pattern in the image plane of an optical system [4±6]. The di raction of an elliptical Gaussian beam truncated by an elliptical aperture has been calculated numerically by Kathuria [7], who found that the beam ellipticity, which is not equal to the ellipticity of the aperture, can be changed in the far ®eld. In this paper, the aperture di raction method is put forward to modify the characteristics of the elliptical focusing spot. The e ects of rectangular and elliptical apertures on the
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