Nanoscale tilt measurement using a cyclic interferometer with polarization phase stepping and multiple reflections.

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.

White light lateral shear interferometer with holographic shear lenses and spatial Fourier transform.

Lateral shear interferometer is a simple yet powerful method for testing wavefronts or measuring refractive index changes. Previously, we have reported a method of using two holographic lenses to obtain shear and to generate a spatial frequency carrier, which was used for quantitative analysis. This technique has some advantages such as stability and instantaneous measurements.

Spatially multiplexed X-Y lateral shear interferometer with varying shears using holographic lens and spatial Fourier transform.

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.

Speckle interferometry with temporal phase evaluation: influence of decorrelation, speckle size, and nonlinearity of the camera.

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.

Shape Measurement by use of Temporal Fourier transformation in Dual-Beam Illumination Speckle Interferometry.

We outline a novel method for determining the shape of an object by use of temporal Fourier-transform analysis in dual-beam illumination speckle interferometry. The object whose shape is to be determined is rotated about an axis, and a number of frames of the image of the object motion are acquired. Temporal in-plane displacement that is due to the object rotation is related to the shape of the object and is retrieved from this large set of data by Fourier transformation.

Speckle interferometry with temporal phase evaluation for measuring large-object deformation.

We propose a new method for measuring large-object deformations byusing temporal evolution of the speckles in speckleinterferometry. The principle of the method is that by deformingthe object continuously, one obtains fluctuations in the intensity ofthe speckle. A large number of frames of the object motion arecollected to be analyzed later.

Laser-induced explosion of gold nanoparticles: potential role for nanophotothermolysis of cancer.

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/cm(2).

Increased sensitivity to in-plane displacements in electronic speckle pattern interferometry.

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.

Oblique incidence and observation electronic speckle-pattern interferometry.

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.

Phase-measuring interferometry: new methods and error analysis.

New methods that can be used to determine phase in phase-stepping interferometry are presented. It is shown that a combination of some of these methods can be used to reduce the error introduced by phase-stepper miscalibration and nonlinearity. Moreover these new algorithms can also be used to detect the presence of miscalibration or phase-shifter nonlinearity.

Diameter measurement of single-mode fiber by using interferometric and imaging techniques.

Two methods to measure the cladding diameter of single-mode fibers are presented. The first method is based on an interference fringe measurement technique. Interference fringe spacing at two different planes is measured to determine the cladding diameter of the fiber.

Quasi-equal-path electronic speckle pattern interferometric system.

Limitations of a quasi-equal-path electronic speckle pattern interferometric system are discussed. We show that by replacement of the reference glass plate with a plano-concave lens the quasi-equal-path electronic speckle pattern interferometric system can be made more versatile. An arrangement to reduce the aberration in the reference beam is also presented.

Pulsed lasers in speckle photography: error owing to pulse width.

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.

Quasi-equal-path electronic speckle pattern interferometric system.

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.

Contrast of the vibration fringes in time-averaged electronic speckle-pattern interferometry: effect of speckle averaging.

This paper presents a detailed investigation of the effect of speckle averaging in electronic speckle-pattern interferometric fringes. The theory states that the constrast of the resultant smoothed fringes increases as the number of frames is increased. It is shown that the contrast of the fringes is optimized with a limited number of superpositions, and further addition results in the reduction of speckle noise with the contrast remaining almost the same.

Vibration fringes by phase stepping on an electronic speckle pattern interferometer: an analysis.

A detailed analysis of the vibration fringes obtained by phase stepping on a time-averaged electronic speckle pattern interferometer is presented. It is shown that the contrast of the fringes remains relatively high for any phase step between 30 degrees and 180 degrees for low electronic noise and fringe density. Also, for the four-phase-stepped method, the vibration fringes have the same contrast as that of the pi-phase-shift method except that the high-frequency speckles are smoothed.

Modified electronic speckle pattern interferometer employing an off-axis reference beam.

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

Simple electronic speckle-shearing-pattern interferometer.

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.

Contouring by electronic speckle pattern interferometry employing dual beam illumination.

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.