Ria Amitasari
Jurusan Fisika, Universitas Diponegoro, Semarang
Articles
5
Documents
REVIEW PENGUJIAN HUKUM MALUS DAN SIFAT OPTIS AKTIF LARUTAN GULA MENGGUNAKAN SISTEM DETEKSI CAHAYA

BERKALA FISIKA Vol 16, No 1 (2013): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Abstract In this paper, we review the test results of Malus’ Law and optical activity of sugarsolution using a system light detector. Two polarizers were used in the experiment to serve thechoice of a certain direction of electric field of light and to determine the change of polarizationangle. The change of transmitted intensity were measured using LDR detector which was thenacquisitioned by microcontroller and displayed via LCD and computer using  Microsoft Visual Studio C#. The experiment result is in agreement to the Malus’ Law with correlation coefficient of 0.99, and by using the equipment we obtain linearity between the change of polarization angle andconcentration of sugar solution, which is appropriate to the theory, as well. The specific rotarypower is (54±2) o/dm(g/mL) in the experimental uncertainty.Keywords: Malus law, change of polarization angle, light detector

DETEKSI DINI KUALITAS MINYAK GORENG DAN STUDI AWAL TINGKAT KEHALALANNYA MENGGUNAKAN POLARISASI ALAMI

BERKALA FISIKA 2014: Berkala Fisika Vol. 17 No. 3 Tahun 2014
Publisher : BERKALA FISIKA

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Abstract

In this paper, we investigate natural light polarization for preliminary test of quality and authentication (halal) level of frying oil. Recently standard methods used are usually based on Indonesian National Standard (SNI), however all parameters are very difficult to be determined simultaneously. On the other hands even the test is time consumed, inexpensive, complicated and also preliminary treatments required, which is a major problem in era of rapid information need. One of an alternative solution is to use natural light polarization method. In the experiment, several vegetable frying oils and animal oils are used to be tested. The change of polarization angle is used to indicate the level of oil quality and its authentication. The result shows that higher polarization indicates lower oil quality relative to the others, which is in agreement to the previous study. This method is, not only, able to differentiate various edible vegetable oils, but also to distinguish edible oils and expired oils. More over, it has a prospect to indicate an authentication of oil that is a subject of a halal or not-halal case.This method is relative simply, not time consumed, conducted accurately without any previous treatments, and it provides a good prospect as a preliminary test for oil quality and its authentication. Keywords: Natural polarization, oil quality, halal or authentication level

PENGARUH GAIN TERHADAP FWHM DAN FWTM PADA CITRA B-MODE ULTRASONOGRAM (USG)

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 2 Tahun 2015
Publisher : BERKALA FISIKA

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Abstract

The effect of gain to The Width at Half Maximum (FWHM) and Full Width at Tenth Maximum (FWTM) on B-mode image ultrasonogram (USG) has been investigated. The aim of this research is to determine the effect of gain on the spatial resolution according the measurements of FWHM and FWTM. The evaluated resolution type is axial and lateral. This research used phantom multipurpose multi tissue with gain (30 dB, 35 dB, 40 dB, 45 dB, 50 dB, 55 dB and 60 dB) on frequency variation source 6,2 Mhz, 8 MHz dan 10MHz. The axial and lateral resolution images were obtained by using USG which uses B-Mode imaging. The measurement was made by using digital image and calculated objectively with MATLAB. The measurement of FWHM and FWTM was obtained from IP-PSF analysis (In Plane-Point Spread Function) using approximation for the Gaussian function. The result shows that there is influence from gain on FWHM and FWTM. The decreasing gain resulted in decreasing of FWHM and FWTM. The decreasing of FWHM and FWTM represents better spatial resolution, and vice versa. Keywords: FWHM, Gain, Point Spread Function, Spatial resolution, USG,