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Author: search.filters.author.Khunrattanasiri, Weerayuth

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    Reflection image model for micro-ellipsometer
    (2019-07-01)
    Khunrattanasiri, Weerayuth
    ;
    Boonsang, Siridech
    High accurate distance measurement currently favors optical techniques. Ellipsometer usually can find the optical properties. The data from the Ellipsometer will transfer to distance data but micro-ellipsometer can provide more accurate than general ellipsometer. The micro-ellipsometer use the back focal plane of an objective lens and measures the optical properties in the different angles. The micro-ellipsometer result is the intensity image. The light reflection model can give us original light reflection images of any objects by determining the refractive index of the material and create a reflection image model. This research created optical reflection models of S<inf>i</inf> O<inf>2</inf>, Au, Ti and Al.
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    Cloud-based optical characterization of hard disk drive recording heads
    (2018-01-01)
    Khunrattanasiri, Weerayuth
    ;
    Yokpradit, Anchyza
    ;
    Tongloy, Teerawat
    ;
    Boonsang, Siridech
    In the hard disk drive (HDD) industry, the measurement of flying height is crucial for the verification of the recording head air-bearing design. The flying performance of recording heads has to be measured and compared with the original design to assure the reliability of HDDs. Optical interferometry is normally used to measure the flying height of recording heads. The key parameter for setting up the measurement is the refractive index, whose values normally deviate depending on machine conditions during the manufacturing processes. The variation in refractive index cannot be identified during flying height measurement because there is no on-line technique for doing so. In this paper, we present a novel technique using inhouse designed micro-ellipsometry to measure the complex refractive index combined with data transfer to a private cloud network via the Internet of Things message queuing telemetry transport (IoT MQTT) protocol. Therefore, the measurement of the complex refractive index can be carried out for each recording head and we can improve the precision of the flying height measurement. In addition, the information about refractive index not only can be shared with a flying height tester to correct the variation in each recording head but also can be used to assist air-bearing designers in the instantaneous validation of their design.
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    A micro-ellipsometry method based on polarization shifting interferometry for determining complex reflective index
    (2017-01-09)
    Khunrattanasiri, Weerayuth
    ;
    Boonsang, Siridech
    In hard disk drive (HDD) industry, the flying height measurement is one of the key processes for validating the recording head production. In order to assure the reliability of the HDD, the flying performance of recording heads has to be measured and compared with the original design. However, as the capacity of HDD increases exponentially, the design of the flying height of a recording head has to be as low as about 10 nanometer. Thus, the precision of flying height measurement is of critical importance. One important input parameter of the flying height measurement is the complex refractive index of the surface of recording heads. In this paper, we present a novel technique for measuring complex reflective index of a relatively small spot size (0.1 micron) using a combined micro-ellipsometry and phase shifting interferometer. This paper shows that the measurement of the complex reflective index can be done for each recording head and that improved precision of the flying height measurement can be obtained.
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    An interferometric back focal plane microellipsometry for the determination of optical properties of a slider's air bearing surface
    (2014-02-12)
    Khunrattanasiri, Weerayuth
    ;
    Boonsang, Siridech
    This paper presents a back focal plane microellipsometer combined with a polarized shifting interferometer. This system is used for the determination of optical phase shift on reflection of a slider's air bearing surface. These optical properties are essential parameters for the flying height measurements in a HDD manufacturing process. The resulting phase shifting images were processed by using Windowed Fourier filters and phase unwrapping techniques, in order to precisely determine the phase of a back focal plane image. The phase images were then used to determine the optical phase shift on reflection values. The results from an aluminum sample show that the measured optical phase shift on reflection values are comparable to the standard values.