Prathan Buranasiri

Demonstration of a single-wavelength spectral-imaging-based Thai jasmine rice identification

A single-wavelength spectral-imaging-based Thai jasmine rice breed identification is demonstrated. Our nondestructive identification approach relies on a combination of fluorescent imaging and simple image processing techniques. Especially, we apply simple image thresholding, blob filtering, and image subtracting processes to either a 545 or a 575 nm image in order to identify our desired Thai jasmine rice breed from others. Other key advantages include no waste product and fast identification time. In our demonstration, UVC light is used as our exciting light, a liquid crystal tunable optical filter is used as our wavelength seclector, and a digital camera with 640 active pixels × 480 active pixels is used to capture the desired spectral image. Eight Thai rice breeds having similar size and shape are tested. Our experimental proof of concept shows that by suitably applying image thresholding, blob filtering, and image subtracting processes to the selected fluorescent image, the Thai jasmine rice breed can be identified with measured false acceptance rates of <22.9% and <25.7% for spectral images at 545 and 575 nm wavelengths, respectively. A measured fast identification time is 25 ms, showing high potential for real-time applications.

Tunable filter-based multispectral imaging for detection of blood stains on construction material substrates part 2: realization of rapid blood stain detection

Based on the blood stain detection method and criteria established in part 1 of this article, we combine and organize all necessary tasks to realize the multispectral imaging-based rapid blood stain detection system. To rapidly detect blood stains on the test surface, the developed system automatically captures the spectral images, extracts their spectral data, determines the positions of blood stains, and accurately highlights the positions of blood stains on the display. To achieve such a system, several tasks are newly introduced, including adjustment of camera exposure times to prevent image saturation or excessive darkness, the search for the sampled clean positions of the substrate to determine the substrate reflectance spectrum, and suitable detection procedures and proper arrangement of criteria to eliminate unnecessary calculations. Parallel processes between image capturing and blood stain identification help shorten the time for blood stain identifications despite a large amount of spectral data to be processed. The developed system can identify blood against several other reddish brown stains on several substrates. The measured average identification times on different test surfaces range from only 23.3 to 28.7 s, including the image capturing process.

Two-wavelength spectral imaging-based Thai rice breed identification

This paper combines multispectral imaging and simple image processing techniques for the non-destructive identification of Thai rice breeds. Especially, we exploit only two fluorescent wavelengths in a 500-580 nm wavelength band and utilize simple image thresholding, blob filtering, and blob analysis techniques in order to identify 8 different Thai rice breeds. Other key features include no waste produced and fast identification time. In our experimental study, UVC light is used as our exciting light, a liquid crystal tunable optical filter is used for our wavelength selection, and a camera with 644×488 active pixels is used to capture desired wavelength images. Milled rice grains from 8 different Thai rice breeds having similar size and shape are tested. There is also one glutinous rice breed in our experiment. Our experimental result shows that by suitably applying image thresholding, blob filtering, and blob analysis to fluorescent images, all Thai rice breeds can be effectively identified.

Third-harmonic pulse generation in one-dimensional photonic crystal structures

Abstract. Enhanced third-harmonic generation in a one-dimensional photonic crystal doped with third-order nonlinear medium was numerically investigated using the multiple-scale method and the split-step Fourier transform. The optimal fundamental frequency for third-harmonic wave generation was determined from the transmission spectrum. The third-harmonic pulse intensities grow, depending on the structure thickness and the fundamental-frequency detuning parameter, which determines the band-edge phase matching condition. Furthermore, the total energy output of third-harmonic pulses, depending on the fundamental-frequency pulse width, may be more than 1000 times the energy produced by a phase-matched bulk medium. A narrow pulse with bandwidth less than the band-edge transmission peak enables high conversion efficiency. The maximum conversion efficiency of the forward component may be 12 to 13 orders of magnitude greater than that of the backward component.

Optical parametric amplification in one-dimensional photonic bandgap structures.

In this paper, optical parametric amplification based on the degenerate four-wave mixing principle in a one-dimensional photonic bandgap (PBG) structure has been numerically studied. First, the multiple scale method was introduced to derive a complete set of nonlinear coupled-mode equations for a finite structure with different inhomogeneous nonlinear coefficients than those used in previous works. This finite structure is composed of 680 dielectric layers, which are alternating half-wave/eight-wave films. The wavelengths of the pump, signal, and idler pulses have been determined from the transmission spectrum, which was illustrated by using the transfer matrix method. The parametric interaction of the pump, signal, and idler pulses inside PBG structure has been numerically simulated by using the split-step Fourier transform method. The results of the simulation have shown that the intensities of the signal and idler have exponential growth with respect to the number of layers in the medium. Meanwhile, pump wavevector detuning directly affects the intensities of both pulses due to a band-edge phase-matching condition that might be achieved from only one optimal detuning parameter. Moreover, both the amplification gain and the conversion efficiency of the idler pulse have been shown to be dependent on the bandwidth of the pump pulse spectrum. A very narrow pulse, with a bandwidth much less than the relevant transmission peak, enables the highest amplification and conversion efficiency in this medium because the most efficient phase-matched condition occurs in this situation. Finally, the conversion efficiency grows exponentially with input pump intensity for several input signal intensities. Furthermore, the maximum conversion efficiencies directly vary with input signal intensity.

Moisture effect of fingerprint using total internal reflection digital in-line holography

Abstract. Total internal reflection (TIR) is normally important in an optical fingerprint scanner. The moisture effect in a fingerprint scanner based on TIR has been explored by using digital in-line holography (DIH). First, the reflection and the transmission technique set up for DIH have been explored by using a positive resolution test target with a line width of 200 μm. From experimental results, the reconstructed image of the reflected DIH is perfect as the image of the transmitted DIH. Due to the advantage for opaque object imaging of the reflected DIH, reflected DIH based on TIR has been selected to investigate the moisture effect of the fingerprint. Fingerprints with moistures of 39%, 54%, 69%, and a soaked finger have been observed. A laser diode of 635 nm and a complementary metal oxide semiconductor camera were used in all of the experimental setups in this research. The reconstructed image of the fingerprint gives a sharper image than the directed recorded image. The fingerprint with higher moisture provided a darker fingerprint image, while the optimum amount of moisture that gives the most complete finger pattern is 54%.

Preparation, Characterization and Finite Element Computation of Cu(Al1/2Fe1/2)O2 Delafossite-Oxide Themoelectric Generator Module

The CuAl1/2Fe1/2O2 delafossite oxide has been synthesized by solid state reaction method for studying thermoelectric properties and measuring thermoelectric generator output electric power. The Finite Element technique was used to compute the output voltage of thermoelectric generator in applying temperature difference on a single bar and a module model with compared to the measurement results. The measurement results of positive sign Seebeck coefficient confirm the p-type conductor of the sample. The properties of Seebeck coefficient, electrical conductivity, and thermal conductivity are range from 260 to 310μV/K, from 7 to16 S/cm and from 2.5 to 3.5 W/cm-K,respectively, in the temperature range of 300 to 960 K. The output voltage of the single bar in dimension 4.2 × 2.5 × 20 mm3 obtained 0.5 to 3 mV on applying temperature difference from 1 to 10 K closely to the Finite Element result. The computing results of the thermoelectric single bar and module in high temperature reveal the output electric voltage of CuAl1/2Fe1/2O2 oxide raises with the temperature and the number of thermoelectric leg increase. In important results, the high value of electric voltage is obtained 0.2 and 0.4 V for the single bar and the module at 950 K.

Fast fluorescent imaging-based Thai jasmine rice identification with polynomial fitting function and neural network analysis

With our single-wavelength spectral-imaging-based Thai jasmine rice identification system, we emphasize here that a combination of an appropriate polynomial fitting function on the determined chain code and a well-trained neural network configuration is highly sufficient in achieving a low false acceptance rate (FAR) and a low false rejection rate (FRR). Experimental demonstration shows promising results in identifying our desired Thai jasmine rice from six unwanted rice varieties with FAR and FRR values of 6.2% and 7.1%, respectively. Additional key performances include a much faster identification time of 30.5 s, chemical-free analysis, robustness, and adaptive learning.

Nanowire Metal-Insulator-Metal Plasmonic Devices

In this paper we theoretically study the responsivity of Metal-Insulator-Metal nanostructures to light illumination over a broad wavelength band (1 - 25 microns) and we examine the role of a local field enhancement and electrostatic field on the responsivity.

Identification of Thai Hom Mali rice using a refractometer

Because Thai Hom Mali, also known as Thai Dawk Mali (KDML105), rice is very popular and its price is high compared to other Thai rice varieties, there is an increase in mixing KDML105 milled and unmilled rice grains with other rice varieties, leading to unqualified KDML105 milled rice products for export and unqualified KDML105 unmilled rice seeds for next plants. Instead of using traditional time- and energy- consuming procedures such as alkaline spreading value and pasting property tests, this paper proposes a fast refractometry-based method to analyze ground milled rice grains dissolved in an alkaline solution. Our idea comes from the fact that due to differences in the amount of amylose content in each rice variety, the refractive index of the milled rice powder dissolved in an alkaline solution can be used to distinguish the desired KDML105 rice from others. In our approach, only 0.1 grams of milled rice powder is ground, it is then dissolved in a 10% potassium hydroxide, and its refractive index is investigated. Our experiment using a temperature-controlled optical refractometer and four Thai rice varieties (KDML105, Pathumthani1, Chainat1, and a Thai sticky rice) shows that the milled KDML105 rice can be distinguished from the remaining three rice varieties with a total false error rate of 6.7% and the required measurement time of < 20 seconds. Key advantages include simplicity, moderate accuracy, and less waste produced.