Linglin Zhu

Bio: Linglin Zhu is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Birefringence & Polarizer. The author has an hindex of 6, co-authored 34 publications receiving 131 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.

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

Lithography illumination system

Abstract: A lithography illumination system, along the transmission direction of the laser light, successively having a laser light source, a collimating and expanding unit, a pupil shaping unit, a first micro-lens array, a micro-integrator rod array, a micro-scanning slit array, a second micro-lens array, a condenser lens group, a mask, and and a motion control unit for controlling the motion of the micro scanning slit array.

Lateral shearing interferometer with variable shearing for measurement of a small beam

Abstract: A lateral shearing interferometer with variable shearing for measurement of a small beam is proposed. The interferometer is composed of a polarization beam splitter, a thick birefringent plate, a quarter-wave plate, a mirror, and an image sensor. The shearing amount can be tiny by using the thick birefringent plate as the shear generator. The shearing amount of the interferometer can be continuously adjusted by rotating the thick birefringent plate, and 2D interferograms can be obtained by rotating the thick birefringent plate along the mutually perpendicular directions. The optical path difference is compensated with a double lateral shearing by using a quarter-wave plate and a mirror. The interferometer is verified by simulation and experiment; the experiment result is well coincident with the simulation result. The usefulness of the interferometer is verified.

Double refraction realtime measuring device and method

Abstract: The invention relates to a double refraction realtime measuring device and method. The device is characterized by comprising an alignment light source, a circular polarizer, a spectroscope, a first Wollaston prism, a second Wollaston prism, a first double quadrant detector, a second double quadrant detector and a signal processing unit. According to the device and the method, double refraction of a sample can be measured in real time, and the measurement result is not affected by light-intensity variation.

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.

Light intensity stabilization based on the second harmonic of the photoelastic modulator detection in the atomic magnetometer.

Abstract: The fluctuations of the probe light intensity seriously affect the performance of the sensitive atomic magnetometer. Here we propose a novel method for the intensity stabilization based on the second harmonic component of the photoelastic modulator (PEM) detection in the atomic magnetometer. The method not only could be used to eliminate the intensity fluctuations of the laser source, but also remove the fluctuations from the optical components caused by the environment. A relative fluctuation of the light intensity of 0.035% was achieved and the corresponding fluctuation of the output signal of the atomic magnetometer has decreased about two orders of magnitude from 4.06% to 0.041%. As the scheme proposed here only contains optical devices and does not require additional feedback controlled equipments, it is especially suitable for the integration of the atomic magnetometer.

Dynamic measurements using a Fizeau interferometer

Abstract: Single-camera frame instantaneous interferometry is an alternative optical test method where environmental noise prohibits conventional phase shifting methods. For the most demanding applications, the instrument should have high light efficiency and sufficient source power to accommodate short camera shutter times, effectively freezing object motion. Here we report on a new instantaneous Fizeau-type interferometer with fully coherent optics that provide high light-efficiency and increasing lateral resolution with zoom, and a novel 4mW, stabilized 633 nm laser source for single-shot metrology with exposures as short as 12 microseconds. We illustrate how this instantaneous measurement capability enables continuous live display of surface profiles and Zernike fits, and dynamic data acquisition for recording varying surface profiles or cavity disturbances at a rate of 82 Hz.

Accurate Interferometric Retardance Measurements

Abstract: A two-polarization Michelson interferometer with a low-retardance beam splitter and digital signal processing is used to measure the retardance of optical devices. Error analysis of the improved optical system and data processing shows that the measurement has an uncertainty of 0.039 degrees for measurements of nominally 90 degrees retarders. Retardance variations arising from coherent reflections in the retarder used for intercomparison add an uncertainty of from 0.005 degrees to 0.03 degrees , increasing the combined measurement uncertainty to as much as 0.049 degrees .

Methods for optical phase retardation measurement: A review

Abstract: Optical-phase-retardation elements are widely used in many fields. Accurate measurement of their phase retardation is crucial to the practical effect of the element’s processing and application. The development and present situation of the methods for optical phase retardation measurement are reviewed, with the wave plate, the most typical phase-retardation element, as an example. The latest research progress in this field is introduced; the principles and characteristics of individual measurement method are summarized and discussed. Three new methods based on laser frequency splitting or laser feedback are presented in detail, in which the laser is not only regarded as a light source but also plays a role of sensor. Moreover, no standard wave plates are needed and arbitrary phase retardation can be measured. Traceability, high precision and high repeatability are achieved as well.