Rotating Ground Glass Plate Research Articles

Theoretical and experimental study of the color of ghost imaging.

In this article, the color of ghost imaging (GI) was studied theoretically and experimentally. The theoretical analysis and experimental data show that the color of GI with rotating ground glass plate and computational GI are the same as the light source. If multiwavelength source is used in these schemes, a full color image without distortion can be obtained. In contrast, the color of GI with spatial light modulator as well as that in a quantum system is a superimposed one, depending on the idle and object light beams, and following the principle of light color superposition. Correspondingly, a full color image can also be obtained under the condition of multiwavelength source, but with color distortion existing.

Ghost imaging with broad distance**Project supported by the National Natural Science Foundation of China (Grant Nos. 61178012, 11204156, 11304179, and 11247240), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20133705110001 and 20123705120002), the Scientific Research Foundation for Outstanding Young Scientists of Shandong Province, China (Grant No. BS2013DX034), and the Natural Science Foundation of

We present a scheme that is able to achieve the ghost imaging with broad distance. The physical nature of our scheme is that the different wavelength beams are separated in free space by an optical media according to the slow light or dispersion principle. Meanwhile, the equality of the optical distance of the two light arms is not violated. The photon correlation is achieved by the rotating ground glass plate (RGGP) and spatial light modulator (SLM), respectively. Our work shows that a monochromic ghost image can be obtained in the case of RGGP. More importantly, the position (or distance) of the object can be ascertained by the color of the image. Thus, the imaging and ranging processes are combined as one process for the first time to the best of our knowledge. In the case of SLM, we can obtain a colored image regardless of where the object is.

Multiwavelength ghost imaging

In this paper, we analyze the multiwavelength thermal ghost imaging with the spatial light modulating system (SLMS) and rotating ground glass plate (RGGP), respectively. We find that the multiwavelength ghost imaging dramatically enhances the signal-to-noise ratio (SNR) of ghost imaging for all types of objects. The $N$-wavelength ghost imaging with SLMS produces ${N}^{2}$ ghost images incoherently added together to form one ghost image whose SNR is ${N}^{2}$ times the one of single-wavelength ghost imaging. The $N$-wavelength ghost imaging with RGGP produces $N$ ghost images incoherently added together to form one ghost image whose SNR is $N$ times the one of single-wavelength ghost imaging. We find that a quantum effect is involved in the thermal light, although in a specific scenario at present. Moreover, the color ghost image obtained by the multiwavelength ghost imaging is better than the monochromatic ghost image in our observation.

Experimental generation of ring-shaped beams with random sources

We have experimentally reproduced ring-shaped beams from the scattered Laguerre-Gaussian and Bessel-Gaussian beams. A rotating ground glass plate is used as a scattering medium, and a plano-convex lens collects the scattered light to generate ring-shaped beams at the Fourier plane. The obtained experimental results are supported with the numerical results and are in good agreement with the theoretical results proposed by Wang et al. [Opt. Express17, 22366 (2009)].

Experimental generation of a partially coherent Laguerre–Gaussian beam

We report experimental generation of a partially coherent Laguerre–Gaussian beam with mode orders 0 and l (i.e., LG0l beam) using a rotating ground-glass plate and a spatial light modulator. Focusing properties of the generated beam are studied both theoretically and experimentally. It is found that the focused intensity of the LG0l beam is shaped through varying the initial spatial coherence, and our experimental results agree well with the theoretical predictions. Our results will be useful in particle trapping and free-space optical communications.

Hanbury Brown–Twiss-type experiments with optical vortices and observation of modulated intensity correlation on scattering from rotating ground glass

The famous Hanbury Brown and Twiss type experiments are performed with optical vortices. Though the intensity correlation for vortices are found to be similar to that of the TEM${}_{00}$ mode of the He-Ne laser used to generate the vortices, an interesting difference is observed when they are scattered through a rotating ground glass plate. For smaller time delays, correlations for vortices follow the same pattern as the scattered Gaussian beam of light except that the vortices decay faster and the rate of decay depends on the order of the vortex. For longer time delays, however, the intensity correlation curves for vortices are found to be modulated and this modulation becomes more prominent as the order of the vortex is increased. This seemingly counterintuitive observation is supported by exact analytical results.

Experimental generation of a radially polarized beam with controllable spatial coherence

We have experimentally generated a radially polarized (RP) beam with controllable state of spatial coherence by using a rotating ground-glass plate and a radial polarization converter. Furthermore, experimental and theoretical analysis of the focusing properties of a partially coherent RP beam is carried out. Our results show that we can shape the beam profile of the focused RP beam by varying its initial spatial coherence, which is useful for material thermal processing and particle trapping. The experimental results are in complete agreement with the theoretical predictions.

Intensity correlation properties of high-order optical vortices passing through a rotating ground-glass plate

We study the intensity correlation properties of optical vortices passing through a rotating ground-glass (RGG) plate and compare them with those of the TEM(00) mode of an He-Ne laser beam passed through the same RGG. We have observed that the intensity correlation curves for optical vortices decrease much faster than the corresponding curve for a TEM(00) mode of the He-Ne laser. The rate of decay of the correlation increases with the increase of order of the vortices. Our experimentally observed results are supported by exact analytical results.

Diffraction-Limited Holography

Experimental determinations of the size of the Airy disk for real image reconstructions of holograms of limited extent have yielded values comparable with those given by diffraction limitation. The holograms used are transmission, side-band holograms of low carrier frequency and are constructed in the far field of the object (~3-microm extent). In reconstruction, the real image is focused, with unit magnification, onto a rotating ground-glass plate and viewed through a microscope with 400x magnification. Comparisons of the reconstructed image with the actual object are made for holographic speeds ranging from f/10 to f/2 using visual, photographic, and photoelectric recordings. Photographic resolution tests, using standard bar patterns, yield a value of 1.05 for the ratio of the observed radius of the Airy disk to that corresponding to diffraction limitation. These tests are in disagreement with photoelectric measurements, the discrepancy being quantitatively ascribable to contrast enhancement in the film.

Intensity Interferometric Imaging Through a Diffusing Medium

It is shown that a correlation interferometer can be used to obtain directly an image of a coherently or incoherently illuminated object through a changing random diffusing plate. An image of a pair of coherently illuminated point sources was obtained through a rotating ground-glass plate using a correlation interferometer.

Spatial coherence of laser light passed through rotating ground glass

The ensemble-averaged spatial coherence of quasi-thermal light, produced by passing a focused laser beam through a rotating ground glass plate, is studied as a function of the illuminated area, the fineness of the glass used, the speed of rotation of the glass, and the laser mode selected as a primary source. It becomes clear that the ensemble-averaged spatial coherence depends strongly upon the illuminated area and on the fineness of the rotating ground glass, and also on the laser mode chosen but not on the speed of rotation of the glass.

レーザードップラー速度計における開口絞りの効果

The paper reports the results of experimental study on the effect of an aperture stop on frequency shift and variation of frequency width of observed beat signals using a laser Doppler velocity meter, which measures linear velocity of diffusing surface of a rotating ground glass plate detecting beat frequency between diffused laser beam and reference laser beam.Three kinds of the aperture stops, a circuler aperture, a horizontal slit and a vertical slit, are introduced in an optical path of the mixed laser beams of deffused and reference to restrict the effective diverging angle of the deffused beam. The experiment shows that decrease of the frequency of 20% as much as and increase of the frequency width of three times as much as the original ones of the beat signals due to increase of the size of the circuler aperture and the length of the horizontal slit from 1mm to 20mm, however increase of the length of the vertical slit has no effect on the beat signals.Refering to the experiment, the dependence of the shape of the beat signal on the intensity distribution and intensity ratio of the deffused beam and the reference beam, the relation between the spot size of the laser beam, surface roughness of the ground glass plate, speckle pattern in the deffused beam, coincidence of the wave fronts of diffused and reference beams and observed interference fringes are discussed.