Digital holography for nondestructive testing

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Name: Suwan Plaipichit

LCSH: Holography.

Othors: Applied Physics -- Thesis (Degree of Doctor)

Othors: King Mongkut's Institute of Technology Ladkrabang. -- Applied Physics -- Thesis.

Abstract: In this thesis, digital in-line holography (DIH) has been used as a tool for nondestructive testing technique. Three different samples i.e. fingerprint, glass bottle, and photorefractive grating inside Ce:BaTiO₃ crystal have been investigated by using this technique. All our DIH nondestructive systems have been composed of a laser diode with 635 nm and a CMOS camera. First, the moisture effect in fingerprint scanner based on total internal reflection which is the important concept in optical finger print scanner has been explored. The reflected and transmitted DIH have been set up and compared the results by using positive resolution test target with line width of 200 μm. From the experimental results, the reconstructed image of reflected DIH is as perfect as the image of transmitted DIH. Due to the advantage for opaque object imaging of reflected DIH, reflected DIH based on TIR has been selected to investigate moisture effect of the fingerprint. The fingerprints with different moistures of 39%, 54%, 69%, and soaked up finger have been observed. Second, the technique for investigating the quality of glass bottle by using DIH has been proposed. The collimated beam laser diode incident on a glass bottle then the image bearing reflected beam consisting of quality profile of the glass bottle has been recorded on a CMOS camera. By using the experimental results and numerically reconstructed images, the defects inside the glass bottle can be detected and the curvature radius of the bottle can be directly calculated by putting the reconstructed distance into mathematical model of a mirror equation. Finally, the grating period of photorefractive anisotropic self-diffraction inside Ce:BaTiO₃ has been investigated by using DIH technique. To write grating inside the crystal, a beam with wavelength of 632.8 nm and power of 10 mW from a He-Ne laser has been separated into two beams and then incident on the crystal with different angles. The highest efficiency of diffraction beams have been founded when the angle between both beams is 20 degrees. To observe the gratings inside the crystal, the transmitted probe beam with opposite polarization of the writing beams has been expanded and incident on the crystal. The transmitted beam has been recorded on a digital camera. To explore the grating periods, both phase and amplitude of the images were reconstructed by numerical process using a computer. Then, the grating periods in photorefractive anisotropic self-diffraction have been measured

King Mongkut's Institute of Technology Ladkrabang. Central Library

Address: Bangkok

Email: Lifelong@kmitl.ac.th

Name: Prathan Buranasiri

Role: Thesis Advisor

Email : kbpratha@kmitl.ac.th

Created: 2014

Modified: 2559-07-04

Issued: 2016-07-04

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Thesis S95d 2014

eng

DegreeName: Doctor of Philosophy (Applied Physics)

Level: Doctoral Degree

Descipline: Applied Physics

Grantor: King Mongkut's Institute of Technology Ladkrabang

©copyrights King Mongkut's Institute of Technology Ladkrabang

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