Papers by Keyword: Lateral Resolution

Abstract: The way of the lateral resolution improvement for 3D nanorelief measurement is proposed. Algorithm for digital processing of measurement data based on deconvolution operation using Wiener filtration is presented. Results of theoretical researches, numerical and optical experiments are given.

Abstract: As is well known, the phase-shifting interferometry techniques allow to reach longitudinal resolution to ~ 0.1 nm, but the value of lateral resolution remains at the level of ~ 1 mm. For providing of high lateral resolution of linear measurements in the interference microscope profilometer it was proposed to use a position detection sensor of sharp edge. Principle of sensor’s measurement is based on registration of laser spot intensity scattered by the measurement sample surface under displacement of sample in the lateral direction. The paper shows the prototype scheme of measurement system containing the Linnik interferometer used for surface nanorelief measurement and a position detection module of sharp edge. Measurement process and experimental results are presented. The combining of measurement results performed by the Linnik interferometer and a position detection sensor of sharp edge can allow us to precisely (better then diffraction limit) define the position of sharp edge on the reconstructed surface nanorelief.

Abstract: In this paper, we investigated a high lateral resolution common-path Fourier domain OCT system with the use of a chemically etched single mode fiber. In our experiments, single mode optical fiber for 840nm was used for preparing the tapered tips. Our system used a conical microlens that was chemically etched by selective chemical etching technique using an etching solution of buffered hydrofluoric acid (BHF). From experimental results, we verified that our proposed optical coherence tomography system could operate as a common-path Fourier domain OCT (FD-OCT) system. Furthermore, we experimentally investigated the chemical etching process of silica-based optical fiber probes by controlling the etching time when applying chemical etching techniques using hydrofluoric acid. We evaluated the beam profile from fiber probe. From these investigations, it was found that etching time was important parameter for sensor probe of optical coherence tomography.

Abstract: In the phased array imaging system, in order to get better images,the lateral resolution need to be improved and the grating lobes need to be eliminated. Restrainning the width of the main lobe is a way to improve the lateral resolution of the system. This article designed the non-periodic distribution of elements to decrease the width of main lobe of the transducer using sparse matrix methods. In this way, we can improve the lateral resolution, resolve the problem of high-density of elements in phased array element, eliminate the impact of the gate lobe, lowerring the effects of radiation in the neighboring elements, save costs and overcome the difficulty in production of elements.

Abstract: In this paper, we propose a high lateral resolution common-path Fourier domain optical coherence tomography (OCT) system with the use of a chemically etched single mode fibre. In our experiments, a single mode optical fibre of 840 nm was used for preparing the tapered tips. Our system used a conical microlens that was chemically etched by a selective chemical etching technique using an etching solution of buffered hydrofluoric acid (BHF). From the experimental results, we verified that our proposed optical coherence tomography system could operate as a common-path Fourier domain OCT system and the apex angle of the chemically etched single mode fibre tip was a very important parameter for generating high-resolution OCT images.

Abstract: This paper presents the resent advances in our research on ultrahigh resolution laser confocal microscopy to further improve the accuracy of non-contact 3D measurement of micro-structural dimensions and profiles at the level of micron/nanometer with emphasis on ways and means to improve axial and lateral resolutions. A scan measuring technique based on differential confocal microscopy is developed using the difference in the distribution of the scanning spot on near and far confocal planes by keeping the detectors off-focus at equal distance before and after the conjugate image plane of the scanning spot. This differential confocal microscopic scan measuring technique can be used to double the measurement sensitivity and obviously expand the linear range to improve the axial resolution, and to locate the tracking zero point at the center of the linear range with the highest sensitivity to achieve the bipolar tracking properties. In addition, this new technique can be used to effectively suppress the light source intensity drift and detector electronic drift and noise to improve the S/N ratio. The differential confocal detection technique can be combined with the optical superresolving filtering technique to improve both lateral and axial resolutions, and the confocal detection technique based on micro optical arrays has a very promising potential application for improving of detection efficiency.