Super-compact shearography based on a single diffractive optical element with 3-in-1 phase mask.

This Letter communicates a new, to the best of our knowledge, designing framework of shearography. The three elementary functional parts of quantitative shearography, namely imaging, shearing, and phase shifting, are integrated into a single diffractive optical element (DOE), named a 3-in-1 phase mask. The idea breaks through the conventional designing routine of shearography, and converts it from the combination of individual optical elements to the spatial manipulation of phase.

Extension and Limits of Depolarization-Fringe Contrast Roughness Method in Sub-Micron Domain.

To guarantee quality standards for the industry, surface properties, particularly those of roughness, must be considered in many areas of application. Today, several methods are available on the market, but some damage the surface to be tested as they measure it by contact. A non-contact method for the precise estimation of sub-micron roughness values is presented, which can be used as an extension of existing roughness measurement techniques to improve them further considering the depolarized light reflected by the sample.

Shear-unlimited common-path speckle interferometer.

A single-aperture common-path speckle interferometer with an unlimited shear amount is developed. This unlimited shear amount is introduced when a Wollaston prism is placed near the Fourier plane of a common-path interferometer, which is built by using a quasi-${4f}$4f imaging system. The fundamentals of the shear amount and the spatial carrier frequency generation are analyzed mathematically, and the theoretical predictions are validated by a static experiment.

Non-Contact Roughness Measurement in Sub-Micron Range by Considering Depolarization Effects.

The characteristics of a surface, particularly the roughness, play an important role in different fields of the industry and have to be considered to ensure quality standards. Currently, there are numerous sophisticated methods for measuring surface roughness but plenty of them cause long-term damage because they are in contact with the sample. This article presents a non-contact method to accurately determine small surface roughnesses resulting from the consideration of the depolarization effects caused by the rough surface.

Real-time dual-sensitive shearography for simultaneous in-plane and out-of-plane strain measurements.

A real-time, dual-sensitive shearography system using a single-wavelength laser was developed for simultaneous and dynamic in-plane and out-of-plane strain measurements. The shearography system is capable of measuring crack-tip deformation fields quantitatively. A spatial multiplexing technique based on Fourier transform is employed for simultaneous and dynamic multi-component phase retrieval.

Dual-directional shearography based on a modified common-path configuration using spatial phase shift.

This paper describes a dual-directional shearography system to address the issue of two-dimensional characterization of the surface strain. A common-path configuration coupled with an additional light path is used to provide the shearing in two directions. One of the three interfering beams is shared by both directional shearograms to improve the light efficiency and enhance the robustness of the system.

Temporal electronic speckle pattern interferometry for real-time in-plane rotation analysis.

A temporal electronic speckle pattern interferometry (ESPI) system is proposed for in-plane rotation measurement. The relationship between the rotation angle and the phase change distribution is established and the rotation direction is indicated by the sign of the partial differential of the phase change distribution. Temporal phase modulation is applied in the proposed symmetric illumination ESPI system.

Non-Contact Surface Roughness Measurement by Implementation of a Spatial Light Modulator.

The surface structure, especially the roughness, has a significant influence on numerous parameters, such as friction and wear, and therefore estimates the quality of technical systems. In the last decades, a broad variety of surface roughness measurement methods were developed. A destructive measurement procedure or the lack of feasibility of online monitoring are the crucial drawbacks of most of these methods.