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The Department of Physics and Optical Engineering at Rose-Hulman Institute of Technology has served as an educational outreach partner with the National Science Foundation sponsored engineering research center, Lighting Enabled Systems & Applications (formally Smart Lighting) for the past eight years. As part of the center, we developed educational materials on smart lighting, developed and taught lighting courses and workshops for both high school teachers and college students, and produced several short educational videos with students on lighting and general optical engineering topics. In this paper we will give examples of research and technical projects that were completed with students, discuss instructional materials that were developed, and describe the content of lighting and optics related educational videos.

Precise measurement of extremely small tilt angles is of immense importance in various scientific and technological applications. Interferometry has always been a tool of great importance in such applications. Most of the conventional interferometric techniques use a Michelson configuration and the problem with this interferometer is that it is extremely sensitive to environmental turbulances and vibrations. In our privious works, we had introduced a cyclic interferometer for the measurement of tilt angles which showed excellent stability against environmental turbulances and vibrations as well as twice the sensitivity. Also, with the introduction of multiple reflections, sensitivity as low as 5 micro radian had been achieved by us. To improve the sensitivity further, we had employed phase shifting techniques. The cyclic configuration being a same path interferometer, we used a polarizing phase shifting technique. For acieving this, we developed a new scheme of polarizing phase shifting techique which is rather simpler compared to those reported in the literature. With this we could precisely measure angles as low as 2 nano radians. However, in these measurements we found that the precise alignment of the quarter wave plate plays an important role in the visibility of the fringes which affects the accuracy of measurement. In this work, we numerically investigate the effect of the misalignment of the quarter wave plate on the visibility of the fringes and consequently on the accurcy of the measurement.

High-accuracy tilt or roll angle measurement is required for a variety of engineering and scientific applications. A cyclic interferometer with multiple reflections has been developed to measure small tilt angles. To accomplish this task, a novel and simple method, phase shift by polarization, was developed. The results of these studies show that the multiple reflection cyclic interferometers can be used to measure object tilts on the order of 0.2 nano-radians. We develop the theory for polarization phase step and show that accurate measurements can be made with the cyclic interferometer.

Accurate measurement of angles is extremely important in various metrological applications. Interferometry has always been an excellent technique for accurate measurements. Several methods have been proposed for accurate tilt measurement using interferometric techniques. Almost all of them use the Michelson configuration which is extremely sensitive to environmental vibrations and turbulences. We know that a cyclic interferometer is extremely stable. Even though it is not sensitive to displacement changes, it is twice sensitive to tilt compared to that of a Michelson interferometer. We have enhanced the sensitivity to measure tilt using multiple reflections in a cyclic interferometer. Since the input beam is collimated, we have studied the effect of aberration of the input beam on the accuracy of tilt measurement. Experimental results on this study are presented in this paper.

The Accreditation Board for Engineering and Technology (ABET) recently revised their published list of programspecific criteria. Beginning during the 2014-15 cycle, all engineering programs which include “optical” and “photonic” in their titles must meet new specific criteria to receive ABET accreditation. One portion of the wording under the curriculum section states “The curriculum must prepare students to have knowledge of and appropriate laboratory experience in: geometrical optics, physical optics, optical materials, and optical and/or photonic devices and systems.” Last year, the Rose-Hulman optical engineering curriculum committee revised our baccalaureate degree program. A portion of this effort sought to improve alignment to the ABET program-specific criteria. Here we review the outcomes of this effort, including our documented continuous improvement process, the realignment of our existing courses along the four tracks laid out by ABET, and the introduction of new undergraduate courses to improve student learning.

The field of speckle metrology has seen a surge in development in the past 10 years owing to advancements in digital cameras and computing power. For instance, a variety of digital speckle correlation (DSC) processes can now be performed in almost real time and therefore speckle techniques has found applications in nondestructive testing (NDT), biology, and medicine. New techniques in terms of optical arrangements and in extracting phase data have been introduced for measuring out-of-plane and in-plane motions in digital speckle interferometry (DSPI) and digital speckle shear interferometry (DSSPI). DSC, DSPI, and DSSPI have also been combined to extend the range of measurements. In addition, quantitative analysis in speckle interferometry has seen a plethora of new software developments for conducting real-time, accurate, complicated, fast, and repeatable measurements with ease. In addition, different methods to process speckle fringes have made analysis equivalent to that of classical interferometry, yet can be applied to all types of real-world specimen. Keywords: speckle photography; digital speckle correlation (DSC); digital image correlation (DIC); digital speckle pattern interferometry (DSPI); digital speckle shear pattern interferometry (DSSPI); speckle fringe analysis; temporal speckle pattern interferometry; speckle phase extraction; biospeckles; white light speckles; speckles in medicine

Aims: This article explores the laser-induced explosion of absorbing nanoparticles in selective nanophotothermolysis of cancer. Methods: This is realized through fast overheating of a strongly absorbing target during the time of a short laser pulse when the influence of heat diffusion is minimal. Results: On the basis of simple energy balance, it is found that the threshold laser fluence for thermal explosion of different gold nanoparticles is in the range of 25–40 mJ/cm2. Conclusion: Explosion of nanoparticles may be accompanied by optical plasma, generation of shock waves with supersonic expansion and particle fragmentation with fragments of high kinetic energy, all of which can contribute to the killing of cancer cells.

Summary Recently a new method to measure object shape and deformation using temporal evolution of speckles in speckle interferometry was reported. The principle behind the method is that certain parameter sensitive to shape or deformation is changed continuously and the fluctuations in the intensity of the speckles are recorded in a large number of frames. The phase data for the whole object deformation is then retrieved by inverse Fourier transformation of a filtered spectrum obtained by Fourier transformation of the signal. In this paper a theoretical evaluation of the amplitude of the signal for inplane sensitive interferometer that uses dual beam illumination is presented. It is shown that signal to noise ratio is better when the speckle size is smaller than the pixel size contrary to the normal assumption that the speckle size be matched to the pixel size.

A novel nondestructive testing (NDT) method is reported in which temporal evolution of the speckles in speckle interferometry is used to measure large object deformations. The basic principle of the method is that continuous object movement introduces fluctuations in the phase of the speckle and is recorded as intensity modulation. Acquiring a large number of frames of the object motion, the phase data for the whole object deformation are then retrieved by the Fourier transformation technique. The method is capable of measuring more than 100 μm in-plane and out-of-plane deformation with speckle interferometry and more than 500 μm for speckle shearing interferometry. The authors discuss the NDT results obtained with the three methods and make some relative comparisons of each.

Measurement of in-plane displacements of a diffuse object by observing the temporal fluctuation of the speckle pattern in a dual-beam illumination speckle interferometer is illustrated. To conceive the temporal changes the object is displaced in its plane continuously. A high-speed camera is used to acquire a number of frames of the image of the object motion sequentially. Through Fourier transformation and inverse Fourier transformation of the frames stacked together, the total phase is determined. Finally, the magnitude of the in-plane displacement of the object motion is extracted. The range of displacement that can be measured using this novel method lies between few microns and over 100 μm on the upper end. Theory together with experimental results are presented in this paper.

Measurement of tilt plays an important role in metrological applications and consequently, several methods have been proposed in the recent past. Classical interferometric methods can measure angles with high accuracy but are easily susceptible to external turbulences. We propose to use a cyclic interferometer to measure tilt in which the sensitivity to tilt measurement is double when compared with that of the classical Michelson interferometer. Since the counter propagating beams travel identical paths, the interferometer is insensitive to external vibrations and turbulence and thus can be used under harsh environmental conditions. The novelty in the technique lies in creating multiple reflections in the tilt mirror to enhance the measurement accuracy by the way of increasing the sensitivity. This paper presents the basics of the interferometer and experimental results to quantify the increase in sensitivity. By increasing the number of reflections, it is shown that sensitivity can be further improved to measure tilt angles below 5 μ rad .

Over the past several years there has been a rapid advancement in solid state lighting applications brought on by the development of high efficiency light emitting diodes. Development of lighting devices, systems and products that meet the demands of the future lighting market place requires workers from many discip lines including engi neers, scientists, designers and architects. The National Sc ience Foundation has recognized this fact and established the Smart Lighting Engineering Research Center that promotes research leading to smart lighting systems, partners with industry to enhance innovation and educates a diverse, world-class workforce. The lead institution is Rensselaer Polytechnic Institute with core partners Boston University and The University of New Mexico. Outreach partners include Howard University, Morgan State University, and Rose-Hulman Institute of Technology. Because of the multidisciplinary nature of advanced smart lighting systems workers often have little or no formal education in basic optics, lighting and illumination. This paper describes the initial stages of the development of self-contained and universally applicable educational modules that target essential optics topics needed for lighting applications. The modules are intended to be easily incorporated into new and existing courses by a variety of educators and/or to be used in a series of stand-alone, asynchronous training exercises by new graduate students. The ultimate goal of this effort is to produce resources such as video lectures, video presentations of students-teaching-students, classroom activities, assessment tools, student research projects and laboratories inte grated into learning modules. Sample m odules and resources will be highlighted. Other outreach activities such as plans for coursework, undergraduate research, design projects, and high school enrichment programs will be discussed. Keywords: Optics education, Lighting education, Course modules

In this paper we extend and study the method for generating contours of diffuse objects employing a dual beam illumination coupled with electronic speckle pattern interferometry. The sensitivity and the orientation of the contour planes are analyzed. A novel method for tilting the planes of contours and experimental results incorporating phase shifting and fringe analysis are also presented. The theoretical and the experimental results show good agreement.

We describe an optical arrangement that increases the sensitivity to in-plane displacement in an electronic speckle-pattern interferometric system. This is accomplished by oblique illumination and observation along the direction of illumination. An anamorphic prism placed in front of the object is used to correct for the eccentricity in the image caused by the oblique observation. The sensitivity to in-plane displacement can be increased to a maximum of approximately λ/2. Experimental results including phase stepping are presented.

The effect of the pulse width of a pulsed laser in the studies of speckle velocimetry and transient vibration analysis is discussed. Because of the motion of the object during an exposure, a sine function is obtained by using the pointwise filtering method. This function modulates the halo along with the Young's fringes. It is shown that for high object velocities the sinc function modifies the halo distribution; as a result, the error in calculating the fringe position increases. An aperture geometry for which the autocorrelation halo is made constant in certain regions is proposed in which the intensity variation in this region is the result of the modulating sinc function only. A closed-form solution for the shift in the position of the fringes in this region is obtained. Experimental results of the simulation are presented.

A new arrangment for an electronic speckle pattern interferometer is reported in which an off-axis reference beam is used, thereby eliminating alignment problems.

Presentation d'un interferometre inverseur employant des composants holographiques. Il est tout a fait adapte au controle optique a chaque fois qu'une detection isolee du coma est necessaire

L'utilisation d'un reseau holographique juste devant le plan image fournit le cisaillement (dedoublement du front d'onde) et conduit a des figures de franges de courbure et de pente

In this paper we discuss a method of wavefront phase detection by differentiation of the interferometric fringes. We show that only one phase step is required to determine the wavefront phase. In the process of differentiation, Moire fringes are formed. Conditions on the angle of tilt introduced between the interfering beams to overcome the formation of Moire fringes are also presented. The method is shown to be suitable for techniques such as null optical testing or interferometric methods where comparison is made between a master and a test. We present in this paper the theory of the method and experimental results obtained for both specular and speckle interferometric fringes.

A quasi-equal-path electronic speckle pattern interferometric system that uses the polarization property of a diffusing object is presented. The fringe pattern is extremely stable with high visibility. Phase stepping in this arrangement is accomplished by translating the glass plate used for obtaining the reference beam. The only alignment that is necessary is that for obtaining a uniform field of view. This experimental arrangement demonstrates high efficiency of laser power usage. An equation for longitudinal alignment tolerance is also obtained.

A simple electronic speckle-shearing-pattern interferometer, in which the image of an object is focused and sheared with a split lens onto a diffuser, is described. The sheared images on the diffuser are focused by a television camera and then digitized and processed in a host computer. The results obtained for two basic types of shearing, lateral and radial, are presented.

We present two new methods for measuring small out-of-plane displacement. These methods are descendents of Leendertz's method in speckle interferometry but provide fringes of good contrast.

Recently, a new method to measure object shape and deformation with temporal evolution of speckles in speckle interferometry was reported. In this method, certain parameters, sensitive to shape or deformation are changed continuously, and the fluctuations in the irradiance of each speckle is recorded. The information over the whole object deformation is retrieved by Fourier-transformation techniques. We present a detailed theory and analyze the influence of decorrelation due to longitudinal and lateral size of the speckles. It is also shown that the method can be used to measure small deformations (less than 5 µm) with higher resolution. Further, the nonlinearity of the camera is shown to enhance the sensitivity.

Michelson interferometer is one of the most popular optical interferometric systems used in optical metrology. Typically, Michelson interferometers are used to measure object displacement with wavefront shapes to one half of the laser wavelength. As testing components and device sizes reduce to micro and nano size, a sensitivity of half the wavelength of light cannot be used to measure several hundred picometer displacement. Multiple-reflection interferometers have been proposed and are used to increase the sensitivity in a Michelson interferometer; however, when altering the number of reflections, the system alignment becomes cumbersome. We describe some of the problems associated with the current multiple-reflection interferometer and introduce a setup for matching path lengths to increase the resolution and allow for the reduction of the stringent requirement on the coherence length of the lasers used. Theoretically, we show that more than 1000 reflections can be achieved. Experimental results of up to 100 reflections are presented in this paper.

Speckles are a three-dimensional self interference pattern formed by a large number of random coherent waves. This results in a granular structure in free space or can be observed to be superposed on the image of the object and sets a fundamental limitation in high-resolution hologram microscopy and coherent imagery. Essentially, speckles are a randomly coded pattern that carries information about the object surface, and also has the rare distinction of being a nuisance and simultaneously a useful tool for measurement. Emergence of better measurement capabilities, newer recording media, faster computers and interfaces, and software has revitalized speckle metrology and has resulted in many fascinating new developments. Scores of books and review articles cover the myriads of applications and developments, and this chapter is intended to provide a concise and precise account of speckles starting from its infancy to the latest developments such as temporal speckle pattern interferometry or digital holography. Attractiveness of speckle methods lies in their ability to measure: large deformations, displacements with variable sensitivity to in-plane and out-of-plane, displacement derivatives, shape of a three-dimensional object, surface roughness, and dynamic displacement. Speckle techniques can nowadays be used to measure a wide range of displacement, sensitivities ranging from 0.25 µm to 150 µm for in-plane and 0.05 to 150 µm for out-of-plane displacements and with shearing techniques to over a 1000 µm. Keywords: speckle; speckle photography; speckle interferometry; electronic speckle pattern interferometry; digital holography

A new mechanism is proposed for selective laser killing of abnormal cells by laser thermal explosion of single nanoparticles - "nano-bombs" - delivered to the cells. Thermal explosion of the nanoparticles is realized when the heat generates within the strongly-absorbing target more rapidly than the heat can diffuse away. On the basis of simple energy balance, it is shown that the lower level of the threshold energy density of a single laser pulse required for thermal explosion of solid gold nanospehere is about 40 mJ/cm2, which is well below the safety standard for medical lasers (100 mJ/cm2) for healthy tissue and cells. The nanoparticle's explosion energy density can be reduced further (up to 11 mJ/cm2) by using gold nanorods due to higher plasmon-resonance absorption efficiency of nanorods. Additionally, the nanorods optical resonance lies in the near-IR region, where biological tissue transmissivity is the highest. Here, the effective therapeutic effect for cancer cell killing can be achieved due to nonlinear phenomena, which accompany the thermal explosion of the nanoparticles: generation of the strong shock wave with supersonic expansion of dense vapor in the cell volume, producing sound waves and optical plasma.

The Physics and Optical Engineering department at Rose-Hulman Institute of Technology offers three degrees at the undergraduate level; physics, optical engineering, and engineering physics. The department recently transitioned a science-based applied optics degree into a B.S (Optical Engineering) degree. With this transition we began the process of seeking accreditation for the optical engineering program through the Accreditation Board of Engineering and Technology (ABET). This paper describes several assessment components of the accreditation process which includes a detailed curriculum mapping exercise to meet engineering standards. We discuss the overall outcome based optical engineering education.

Education in optics has evolved in the last decade into an application and enabling technology field and it is emerging as an engineering field in the last couple of years. Therefore, as a newly evolving program, the emphasis is placed on the overall learning outcomes of the students. In that regard we have developed concept inventory questions in optical engineering to monitor and assess improvements in student learning. The concept inventory questions are given to students twice during a course, one at first day of class and the same questionnaire is given to them during the last day of class. The pre-class test is used to assess prior knowledge of the students and the second test is used to measure the learning experience of the students. The results of the test are used to monitor and improve overall education experience of the students.

The optics educational programs at Rose-Hulman Institute of Technology have progressed and evolved over the past twenty years. Beginning with a modest undergraduate area minor in applied optics we now offer bachelors and masters degree programs in optical engineering. Distinctive elements of the current optical engineering programs including courses and curricula will be discussed.

Rose-Hulman has a history of meeting the need for optical engineers via the Applied Optics Programs since 1983. We have changed our degree program to Optical Engineering and will seek ABET accreditation. The present paper will deal with the step taken to accomplish this and define the mission of the degree program.

Rose-Hulman has a history of meeting the need for optical engineers via the Applied Optics Programs since 1983. We have changed our degree program to Optical Engineering and will seek ABET accreditation. The present paper will deal with the step taken to accomplish this and define the mission of the degree program.

Lateral shear interferometry operating in the convergent beam mode has been used for testing optical components. This method is simple and phase information of the wavefront has conventionally been extracted using phase stepping techniques. We propose to use defocus, which introduces uniform tilt as a means of extracting phase information via two procedures, namely spatial phase stepping and spatial frequency carrier method. Experimental results are presented that show the wavefront phase extracted with defocus before and after the focal point of the lens.

Multiple wavelength interferometry is used to increase the range of unambiguity beyond that of single wavelength interferometry. In wavelength scanning interferometry, the frequency of the intensity modulation induced by the wavelength change is determined independently for each image pixel. The tuning range determines the resolution of measurements, while the tuning step limits the range of the measurements. Laser diodes can be tuned, but an external cavity is needed for a larger mode hop free wavelength variation. Polished and optically rough surfaces can be analyzed in the same manner. Acquisition times of a few seconds and high resolutions were obtained. In a new development, the application of temporal evaluation of speckles for deformation and shape measurement will be discussed. It turns out that spectral and temporal phase analysis can be very useful for many applications in optical metrology.

Interferometry using a single wavelength delivers the surface topography and surface heights of optically polished surfaces. However, discrete steps and holes cannot be determined, the sensitivity is fixed, and the analysis of optically rough surfaces is not possible. Some of these limitations can be overcome by using two or more wavelengths. In wavelength scanning interferometry, the frequency of the modulation induced by the wavelength change is determined independently for each image pixel. The tuning range determines the resolution of measurements, while the tuning step limits the range of the measurements. Laser diodes can be tuned, but an external cavity is needed for a larger mode hop free wavelength variation. Polished and optically rough surfaces can be analyzed in the same manner. In a new development, the application of temporal evaluation of speckles for deformation and shape measurement will be discussed. It turns out that spectral and temporal phase analysis can be very useful for many applications in optical metrology. Experimental results will support the methods discussed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Absolute interferometry can be a powerful tool for distance and shape measurement. Two and more wavelengths can be used to increase the range of unambiguity in interferometry. Furthermore it leads to the possibility to apply interferometric methods to measure optical rough surfaces. A continuously tunable laser in a two beam unequal path interferometer is used to overcome the ambiguity problem of classical interferometric methods. While the laser wavelength is tuned continuously, the variation of the interference intensity is recorded sequentially. At each image pixel the frequency of the signal modulation is analyzed, giving the absolute depth information for the corresponding object point. The wavelength tuning step governs the depth of measurement whereas the tuning range determines the depth resolution to be obtained. The method can be applied for optical as well as for technical surfaces. In the latter case, the intensity variation is observed independently in each speckle. However, the resolution of the measurement of optically rough surfaces is limited by the surface roughness. The continuous tuning of the wavelengths is performed with a diode laser with external cavity where a frequency variation of 30 nm can be obtained without mode hops within one second. Furthermore a novel method to measure the shape and steps heights by rotating the object and using temporal evaluation of the speckles' modulation is presented. Currently a temporal Fourier- transformation is used, similar to the evaluation method used in wavelength scanning interferometry.

Previously, we reported a simple method to obtain lateral shear in both the x - and y -directions using a multiplexing technique. The phase data was extracted using the inherent spatial carrier fringes formed due to the tilt in the two sheared beams. In this article, we report that an error in phase map is introduced when the band-pass-filtered Fourier transform (FT) spectrum is not centered prior to performing the inverse FT to obtain the phase. We also found that intentionally introducing aberrations when capturing dynamic fluctuations in the wave front, resulted in controlling the spread of the Fourier spectrum.

Current methods in shear interferometry provide shear only along one direction at a time. We propose a method in which interferograms with shear along the x, y, and xy directions can be obtained simultaneously from a single exposure recording via the concept of spatial multiplexing. The method utilizes holographic lenses, which have been recorded on a single plate with their optical centers translated along the x and y directions. The phase information is extracted through the Fourier transform method. In addition, this technique also provides a method to obtain interferograms with shear in multiples of the original shear along the x and y axis in one single frame capture due to the nonlinearity inherent in the phase holographic lens.

Testing with lateral and radial shears is becoming standard in optical shops. Of late, holographic optical elements have proven to be easy and simple to set up, and can be used in both a collimated and convergent beam. However, there is very little work on making quantitative measurements using a symmetric radial shear. We demonstrate a simple method of obtaining both asymmetric and symmetric radial shears, and use the inherent tilt in the wavefronts to perform spatial Fourier transformation to extract phase maps. This radial shear interferometer is also suitable for static and dynamic situations.

In this paper we discuss the implementation of a project oriented laboratory course in opticseducation. Through our discussion we show the relevance and necessity for such a course. The course is tailored not only to make the students to learn concepts, but to build a product from scratch tocompletion. Emphasis is also made on the design, performance, marketing and aesthetics of theproduct.Key words: optics education1.0 iNTRODUCTIONOptics is interdisciplinary in nature with applications covering a broad range of fields.Although optics originated from physics it has evolved into a field that is a mixture of physics andengineering. In this context the method ofteaching and even the learning styles ofthe students aredifferent from conventional physics students. Therefore, optics courses are usually a blend of newtechnology, engineering and physics. However, the traditional sequence in a course is to have a laboratory associated with the course or even a stand alone laboratory course. Laboratory experiencesprovide the tool for understanding the basic ideas but do not necessarily provide the background for

In this paper further discussions on some new methods proposed in an earlier paper on phase stepping interferometry is detailed. These studies reveal that certain algorithms are more sensitive to miscalibration and nonlinearity and can be better candidates to detect the presence of phase shifter miscalibration or nonlinearity. A simplified approach to the understanding of the error and its reduction/elimination in phase shifting interferometry are also presented.

In this paper we propose a new method of shearing in an electronic speckle pattern shearing interferometry using holographic gratings. The system we are proposing consists of two parts: 1) to image the object onto an intermediate ground glass, and 2) the image on the ground glass is in turn imaged onto the photosensor of a CCD camera. A holographic grating placed in front of the ground glass screen is used for shearing the two images and for introducing phase stepping.

Testing with a single holographic lens or grating in a collimated beam is normally not possible because of the inherent tilt caused in the wavefront. The tilt between the two beams in shearing creates a large number of linear fringes which overshadow the information about the wavefront. However, here, we show that we can use this tilt to make quantitative measurements which was otherwise not possible. In the novel method, we obtain shear in a relatively simple way, and at the same time we extract phase information using spatial Fourier transform technique. This technique is suitable for making quantitative measurement of wavefront and disturbances in turbulent conditions. Here, we demonstrated the real-time phase measurement capacity of the interferometer, a result of one such application is shown.

In this paper we discuss an oblique incidence and observation electronic speckle-pattern interferometer, in which we use an anamorphic prism in front of the object. A collimated beam traveling through the prism is partly reflected at the base of the prism. The reflected light is the reference beam and the transmitted light illuminates the diffuse object, thereby generating the object beam. In this scheme the object and the reference beams are collinear. A new scheme that uses two prisms and permits phase stepping is also presented.

In this paper a comparison of different techniques to obtain vibration patterns by phase stepping on an electronic speckle pattern interferometer (ESPI) is made. The theoretical evaluation of the contrast of the fringes shows that the (pi) phase step method gives good contrast; however, the four step method gives the same contrast along with better pictorial representation. Speckle averaging on the other hand also increases the contrast of the fringes apart from smoothing of speckles. Experimental results corroborating the theoretical predictions are also presented.

The design and system performance of an infrared phase-stepping interferometer is reviewed. This instrument is capable of measuring rms surface roughness with a repeatability of 0.02 waves. The instrument uses a 4-bucket unwrapping algorithm. Calibration of the interferometer and removal of inherent system aberrations are discussed along with the system performance, including repeatability and accuracy. The interferometer is an all-reflective optics design to permit use at any wavelength, accommodating both far- (10.6 micron) and near- (5 micron) infrared sources. Testing applications include infrared windows and surface testing.

Described in this paper is a compact phase measuring ESPI system that incorporates single mode fiber and diode laser. The single mode fiber along with diode laser provides ease of system arrangement but also causes wavelength fluctuation and instability. The wavelength instability was reduced to an acceptable level with an optical isolator. Experimental studies on wavelength stability of the diode laser, the back-reflection intensity from the fiber ends, and their influence on the system are presented.

In this paper we discuss a fiber optic electronic speckle pattern interferometer (ESPI) for obtaining 3D information about surface deformation. Phase stepping is introduced by stretching the fiber wrapped around a piezo-electric transducer. Two schemes to stretch the fiber are discussed. Also calibration of the phase step is critical in phase measurement techniques for obtaining good phase plots. In this paper we outline a method used for calibrating the stretcher. We also discuss the error in the phase caused by temperature changes.

Fiber optic Mach-Zehnder interferometric sensors for the measurement of various physical parameters such as pressure temperature and magnetic fields are well known and documented. This paper deals with the construction of a fiber optic sensor incorporating He-Ne and diode lasers. Preliminary experimental results for temperature sensing are reported.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.