Aijun Zeng

Bio: Aijun Zeng is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Waveplate & Lens (optics). The author has an hindex of 9, co-authored 111 publications receiving 405 citations.

Simultaneous measurement of retardance and fast axis angle of a quarter-wave plate using one photoelastic modulator

Abstract: A method for simultaneous measurement of the retardance and the fast axis angle of quarter-wave plate using one photoelastic modulator is presented. A laser beam passes through a polarizer, a photoelastic modulator, the quarter-wave plate to be measured, and an analyzer to be detected. Before and after the quarter-wave plate is rotated 45° at any initial fast axis direction, two detection signals are obtained to resolve simultaneously the retardance and the fast axis angle. In experiments, a quarter-wave plate was measured with fast axis angles from −89° to 90°. The average and the standard deviation of the retardances at different fast axis directions are respectively 89.50° and 0.17°. The maximum measurement deviation of the fast axis angle is 0.5°. The usefulness of the method is verified.

Effects of coherence on anisotropic electromagnetic Gaussian-Schell model beams on propagation

Abstract: An analytical formula for the cross-spectral density matrix of the electric field of anisotropic electromagnetic Gaussian-Schell model beams propagating in free space is derived by using a tensor method. The effects of coherence on those beams are studied. It is shown that two anisotropic stochastic electromagnetic beams that propagate from the source plane z=0 into the half-space z>0 may have different beam shapes (i.e., spectral density) and states of polarization in the half-space, even though they have the same beam shape and states of polarization in the source plane. This fact is due to a difference in the coherence properties of the field in the source plane.

High efficiency all-dielectric pixelated metasurface for near-infrared full-Stokes polarization detection

Abstract: Pixelated metasurfaces integrating both the functions of linear polarization and circular polarization filters on a single platform can achieve full-Stokes polarization detection At present, the pixelated full-Stokes metasurfaces mainly face the following problems: low transmission, low circular dichroism (CD) of circular polarization filters, and high requirements in fabrication and integration Herein, we propose high performance ultracompact all-dielectric pixelated full-Stokes metasurfaces in the near-infrared band based on silicon-on-insulator, which is compatible with the available semiconductor industry technologies Circular polarization filters with high CD are achieved by using simple two-dimensional chiral structures, which can be easily integrated with the linear polarization filters on a single chip In addition, the dielectric materials have higher transmission than metal materials with intrinsic absorption We experimentally demonstrated the circular polarization filter with maximum CD up to 70% at a wavelength of 16 μm and average transmission efficiency above 80% from 148 μm to 16 μm Therefore, our design is highly desirable for many applications, such as target detection, clinical diagnosis, and polarimetric imaging and sensing

Generation of trapezoidal illumination for the step-and-scan lithographic system.

Abstract: To meet the uniform dose exposure in optical lithography, it is desirable to get uniform illumination and trapezoidal illumination in the scanning direction on the wafer for the step-and-scan lithographic system. A design strategy for trapezoidal illumination is proposed which offers both high uniformity illumination and fixed integral energy of trapezoidal illumination in a different illumination pattern. The strategy describes a light uniform device which contains a microlens array, a microcylindrical array, and a Fourier lens and produces trapezoidal illumination directly at the scanning slit. Compared with the conventional method to obtain the trapezoidal illumination, the strategy in this paper reduces the difficulty of assembly and has the advantage of simplicity and directness without blocking energy. This method utilizes energy of the lithographic system more effectively, and it improves the throughput of the lithography. The simulation results show that this method not only maintains the uniformity of trapezoidal illumination but also improves the energy utilization.

Device and method for measuring phase retardation distribution and fast axis azimuth angle distribution in real time

Abstract: Device and method for measuring phase retardation distribution and fast axis azimuth angle distribution of birefringence sample in real time The device consists of a collimating light source, a circular polarizer, a diffractive beam-splitting component, a quarter-wave plate, an analyzer array, a charge coupled device (CCD) image sensor and a computer with an image acquisition card The method can measure the phase retardation distribution and the fast axis azimuth angle distribution of the birefringence sample in real time and has large measurement range The measurement result is immune to the light-intensity fluctuation of the light source

Measurement of intraocular distances by backscattering spectral interferometry

Abstract: The diffraction tomography theorem is adapted to one-dimensional length measurement. The resulting spectral interferometry technique is described and the first length measurements using this technique on a model eye and on a human eye in vivo are presented.

On the diffraction theory of optical images

Abstract: The theory of image formation is formulated in terms of the coherence function in the object plane, the diffraction distribution function of the image-forming system and a function describing the structure of the object. There results a four-fold integral involving these functions, and the complex conjugate functions of the latter two. This integral is evaluated in terms of the Fourier transforms of the coherence function, the diffraction distribution function and its complex conjugate. In fact, these transforms are respectively the distribution of intensity in an 'effective source', and the complex transmission of the optical system-they are the data initially known and are generally of simple form. A generalized 'transmission factor' is found which reduces to the known results in the simple cases of perfect coherence and complete incoherence. The procedure may be varied in a manner more suited to non-periodic objects. The theory is applied to study inter alia the influence of the method of illumination on the images of simple periodic structures and of an isolated line.

Mueller matrix polarimetry with four photoelastic modulators: theory and calibration

Abstract: A spectroscopic Mueller matrix polarimeter with four photoelastic modulators (PEMs) and no moving parts is introduced. In the 4-PEM polarimeter, all the elements of the Mueller matrix are simultaneously determined from the analysis of the frequencies of the time-dependent intensity of the light beam.

Changes in the statistical properties of stochastic anisotropic electromagnetic beams on propagation in the turbulent atmosphere.

Abstract: We report analytic formulas for the elements of the e 2 X2 cross-spectral density matrix of a stochastic electromagnetic anisotropic beam propagating through the turbulent atmosphere with the help of vector integration. From these formulas the changes in the spectral density (spectrum), in the spectral degree of polarization, and in the spectral degree of coherence of such a beam on propagation are determined. As an example, these quantities are calculated for a so-called anisotropic electromagnetic Gaussian Schell-model beam propagating in the isotropic and homogeneous atmosphere. In particular, it is shown numerically that for a beam of this class, unlike for an isotropic electromagnetic Gaussian Schell-model beam, its spectral degree of polarization does not return to its value in the source plane after propagating at sufficiently large distances in the atmosphere. It is also shown that the spectral degree of coherence of such a beam tends to zero with increasing distance of propagation through the turbulent atmosphere, in agreement with results previously reported for isotropic beams.

Active laser radar systems with stochastic electromagnetic beams in turbulent atmosphere.

Abstract: Propagation of stochastic electromagnetic beams through paraxial ABCD optical systems operating through turbulent atmosphere is investigated with the help of the ABCD matrices and the generalized Huygens-Fresnel integral. In particular, the analytic formula is derived for the cross-spectral density matrix of an electromagnetic Gaussian Schell-model (EGSM) beam. We applied our analysis for the ABCD system with a single lens located on the propagation path, representing, in a particular case, the unfolded double-pass propagation scenario of active laser radar. Through a number of numerical examples we investigated the effect of local turbulence strength and lens’ parameters on spectral, coherence and polarization properties of the EGSM beam.