Adam Styk

Tilt-shift error detection in phase-shifting interferometry

Temporal phase shifting in automatic interferogram analysis offers very high accuracy of phase retrieval providing that several experimental conditions are met. The paper is focused on the calibration error of unequal phase changes across the interferogram field, i.e., tilt-shift error. For its detection the lattice-site representation of phase shift angles is proposed. The error can be readily discerned using (N+1) algorithms with the last frame overlapping the first one. Four and five frame algorithms are considered. The influence of experimental parameters on the error detection sensitivity is discussed. Numerical studies are complemented by experimental results.

Phase-shifting method contrast calculations in time-averaged interferometry: error analysis

Numerical simulations of the influence of the phase step miscalibration and average intensity changes between the registered frames on the time-averaged interferogram contrast calculated using the temporal phase-shifting (TPS) method are presented. The amplitude of sinusoidal vibration studied by the time-averaged method is encoded in the interferogram contrast or intensity modulation described by the zero-order Bessel function. The properties of the TPS method used for contrast determination are established. Experimental studies of vibration mode patterns of silicon microelements with specular reflection surfaces provide corroboration of theoretical and numerical findings.

Fizeau interferometer for quasi parallel optical plate testing

In this paper we present our proposal of processing three-beam interferograms obtained in a Fizeau interferometer when testing quasi-parallel optical plates. If the intensities of three interfering beams reflected from the front and back surfaces of the investigated plates and from the reference flat are nearly equal, the modulation distribution of the pattern encodes the information of the plate optical thickness variations, whereas the phase distribution contains the information about the sum of profiles of both surfaces (uniform refractive index distribution is assumed). Both maps can be derived using a combination of different interferogram analysis techniques such as Temporal or Spatial Carrier Phase Shifting and Vortex Transform. As a result separate information about both surfaces from a single measurement can be obtained. The situation complicates, however, when noticeable difference of the beam intensities occurs. We prove that in this case the modulation still contain useful information on the optical thickness of the investigated plate. Numerical studies of the method working principle are complemented by experimental results.

Interferometric methods for static and dynamic characterizations of micromembranes for sensing functions

We present a methodology for static and dynamic testing of mechanical properties of microelements. The measurement path includes temporal phase shifting interferometry for quantitative static shape elements analysis. This is followed by determination of the resonance frequency by means of modified time average interferometry and transient amplitude and phase maps of vibrating micromembrane capturing and evaluation by phase shifting stroboscopic interferometry. Proper application of combination of these methods allows for quick and accurate analysis of micromembranes and optimization of their manufacturing conditions.

Studies of the properties of the temporal phase-shifting method applied to silicone microelement vibration investigations using the time-average method

Numerical simulations of the influence the phase step miscalibration and average intensity differentiation between the frames on the calculated interferogram contrast using the temporal phase shifting method (TPS) are presented. The fringe function includes in its argument the amplitude of vibration studied by the time-average method. Some features of the TPS method known from the interferogram phase calculations are confirmed and properties characteristic to contrast determination are established. Experimental studies of vibration resonant mode patterns of silicone microelements provide corroboration of theoretical and numerical findings.

Double degree master program: Optical Design

Modern tendencies of higher education require development of master programs providing achievement of learning outcomes corresponding to quickly variable job market needs. ITMO University represented by Applied and Computer Optics Department and Optical Design and Testing Laboratory jointly with Warsaw University of Technology represented by the Institute of Micromechanics and Photonics at The Faculty of Mechatronics have developed a novel international master double-degree program “Optical Design” accumulating the expertise of both universities including experienced teaching staff, educational technologies, and experimental resources. The program presents studies targeting research and professional activities in high-tech fields connected with optical and optoelectronics devices, optical engineering, numerical methods and computer technologies. This master program deals with the design of optical systems of various types, assemblies and layouts using computer modeling means; investigation of light distribution phenomena; image modeling and formation; development of optical methods for image analysis and optical metrology including optical testing, materials characterization, NDT and industrial control and monitoring. The goal of this program is training a graduate capable to solve a wide range of research and engineering tasks in optical design and metrology leading to modern manufacturing and innovation. Variability of the program structure provides its flexibility and adoption according to current job market demands and personal learning paths for each student. In addition considerable proportion of internship and research expands practical skills. Some special features of the “Optical Design” program which implements the best practices of both Universities, the challenges and lessons learnt during its realization are presented in the paper.

Derivation of quasi-parallel glass plate parameters tested in a Fizeau interferometer

The paper deals with a common problem in measuring surface flatness of transparent quasi-parallel plates in a Fizeau interferometer. The beam reflected from the rear surface leads to a complicated interferogram intensity distribution. The application of phase shifting for the plate front surface flatness determination becomes ineffective. We propose a new computation approach to suppress spurious modulations. First we find a two-beam-like interference pattern relevant to plate thickness variations using either temporal or spatial phase shifting. Its distribution is calculated using the Hilbert transform. The residual spherical aberration of the illuminating beam and the shape of the reference flat (determined by an absolute flatness testing conducted with the same interferometer) are subtracted from the plate thickness distribution. In this way the shape of the front surface is obtained. Numerical studies are complemented by experimental results.

Time-average interference microscopy for vibration testing of silicon microelements

Fast-growing applications of microelements and microsystems, including actuators and sensors, introduce pioneering requirements on their design and testing to ensure product quality and reliability. Optical whole-field experimental techniques are of particular interest because of their speed, noncontact and noncontaminating character. Vibration testing enables providing material properties at the microlevel, design validation, and the information for the manufacturing process optimization. In particular, time average two-beam interference microscopy with automated computer processing of interferograms using the temporal phase shifting (TPS) method is reviewed. The principle of retrieving the zero-order Bessel function (sinusoidal vibrations) by calibrating the contrast variation or intensity modulation of time-average recordings is presented. The influence of main experimental errors is discussed using numerical simulations and comparisons with experimental data. Exemplary results of measurements performed with active micromembranes and AFM cantilevers are presented.

Parallel approach to MEMS and micro-optics interferometric testing

The paper presents the novel approach to an interferometric, quantitative, massive parallel inspection of MicroElectroMechanicalSystems (MEMS), MicroOptoElectroMechanical Systems (MOEMS) and microoptics arrays. The basic idea is to adapt a micro-optical probing wafer to the M(O)EMS wafer under test. The probing wafer is exchangeable and contains one of the micro-optical interferometer arrays based on: (1) a low coherent interferometer array based on a Mirau configuration or (2) a laser interferometer array based on a Twyman-Green configuration. The optical, mechanical, and electro-optical design of the system and data analysis concept based on this approach is presented. The interferometer arrays are developed and integrated at a standard test station for micro-fabrication together with the illumination and imaging modules and special mechanics which includes scanning and electrostatic excitation systems. The smart-pixel approach is applied for massive parallel electro-optical detection and data reduction. The first results of functional tests of the system are presented. The concept is discussed in reference to the future M(O)EMS and microoptics manufacturers needs and requirements.

Design, technology and signal processing for DOE-based microinterferometer array applied in new generation M(O)EMS test equipment

The paper introduces different approaches to overcome the large ratio between wafer size and feature size in micro production. The EU-project SMARTIEHS develops a new concept for high volume M(O)EMS testing. The design of the test station is presented and the advancements compared to the state of the art are introduced within the following fields: micro-optical laser interferometer (LI) design, DOE-based microinterferometer production, smart-pixel camera and signal processing for resonance frequency and vibration amplitude distribution determination. The first experiments performed at LI demonstrator are also reported.