A Nd:YAG laser (1064nm, 120mJ, and 8ns) was focused on various types of fossil samples, including fossilized buffalo horns (around 400 000 and 1×106yr old, respectively) found in Sangiran, Indonesia. Such fossils represent an important starting point for tracing man’s origin and evolution during the Pleistocene era. Carbon emission was found to decrease significantly with the degree of fossilization and no carbon emission was found in a horn fossil dated at 1×106yr. Some molecular band spectra were also found in all the fossils examined in this study. It was assumed that by combining information on carbon emission, hydrogen emission, and molecular band spectra that the degree of fossilization might be quantitatively calculated. Further results showed that silicon emission is not detected in old fossils, but it is present as a major constituent. This is probably due to the fact that silicon is strongly bound to other elements in old fossils and is ablated in the form of clusters. In order to prove the above hypothesis, a thin film of an old fossil was deposited on a silver plate substrate by means of a laser ablation technique. The resulting film was then irradiated and atomic emission lines of silicon were clearly detected. A comparative study of the low-pressure plasma introduced in this study was conducted using the well-known laser-induced breakdown spectroscopy technique and the results confirmed that operating conditions at atmospheric pressure are unfavorable for a fossil analysis.

AbstrakTelah dikembangkan probe sensor kelembaban menggunakan serat optik dengan cladding gelatin. Pada probe sensor kelembaban ini, cladding asli serat optik diganti dengan lapisan gelatin sebagai cladding sensitif kelembaban. Untuk menguji respon sensor serat optik yang dibuat, dilakukan pengukuran intensitas cahaya yang ditransmisikan pada probe serat optik untuk setiap variasi perlakuan kelembaban berbeda. Respon probe sensor serat optik ini diukur dari kelembaban 42% hingga 99% RH, hasilnya memperlihatkan kurva transmisi optik berbavariasi terhadap nilai kelembaban relatif (RH). Transmisi optik di dalam probe serat optik meningkat terhadap kenaikan nilai RH pada suatu rentang panjang gelombang spesifik, yaitu pada spektrum pita hijau hingga merah (500 nm -700 nm), dengan variasi signifikan pada rentang 600 nm sampai 650 nm atau dalam pita spektrum kuning hingga merah. Panjang gelombang dimana intensitas maksimum transmisi optik terjadi pada panjang gelombang 610 nm. Dengan demikian, probe sensor kelembaban serat optik ini dapat merespon kelembaban dari 42 %R hingga 99%H dengan respon terbaik pada rentang kelembaban 60%RH hingga 72%R yang memiliki linieritas dan sensitifitas yang cukup baik. AbstractDevelopment of Fiber-Optic Humidity Sensor Probe with Gelatin Cladding. Humidity sensor based on optical fiber with gelatin cladding has been developed. In this humidity sensor probe, the origin cladding of optical fiber is replaced by gelatin coating as humidity sensitive cladding. Testing of the optical fiber sensor probe was conducted by measuring of light intensity transmitted on the optical fiber probe for each variation of different humidity treatments. Response of the optical fiber sensor probe measured from 42%RH to 99%RH, the results show an optical transmission curve varied with relative humidity (RH). Optical transmission in the optical fiber probe increase with RH value at a specific wavelength range, that is from green to red spectrum bands (500 nm -700 nm), where a significant variation from 600 nm to 650 nm in yellow to red spectrum bands. Wavelength where is a maximum intensity of optical transmission occurs at 610 nm. Therefore, the optical fiber humidity sensor probe could response humidity form 42%RH to 99%RH with the best response in humidity range of 60%RH to 72%RH that is have a good linearity and sensitivity.

In this research it is applied a computer vision system by using artificial neural network for the identification and defect detection on several samples of the available textile's woven fabrics. Several textural features that extracted by the Neigboring Greylevel Dependence Matrix (NGDM), and GreylevelRun Length Matrix (GRLM), are used as input data for the network, which was trained by the backpropagation method. The results of experiment indicated that the system can identi& three product-types i.e. plain, twill, and sateen weaves, and detect several defects :pick's broken, pick's inhomogeinity, reed-mark, and dirties within more than 80% degree of correctness.

An Nd-YAG laser (1064 nm, 120 mJ, 8 ns) was focused on various types of solid organic samples such as a black acrylic plate, a black polyvinyl chloride plastic sheet, and a methoxy polyaniline film coated on the surface of a glass substrate, under a surrounding air pressure of 2 Torr. A modulated plasma technique was used to study the mechanism of excitation of the emission of the organic material. As a result, we conclude that ablated atoms and molecules are excited by a shock-wave mechanism, similar to the case of hard samples such as metal. The ablation speed of hydrogen emission (H I 656.2 nm) was examined and the results show that the release speed of the ablated atoms is relatively low (less than Mach 10) and persists for a longer period of time (around 1 μs); this phenomenon can be understood by assuming that the soft target absorbs recoil energy, causing a low release speed of ablated atoms which would form the shock wave. This was overcome by placing a subtarget on the back of the soft sample so as to enhance the repelling force, thus increasing the release speed of the atoms. A possible application of the low-pressure plasma on an organic solid was demonstrated in the detection of chlorine in a black polyvinyl chloride plastic sheet.

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