At present, most of the spectrometers used in food detection have some problems such as complex operation, large volume and high cost, which are not conducive to their popularization and application. Therefore, we have developed a small-scale Bluetooth fluorescence spectrometer which can be used for the detection of vegetable oil. The 405 nm semi-conductor laser can be integrated in the spectrometer to excite the fluorescence spectrum of vegetable oil, the spectrum data detected by the spectrometer is transmitted to the Android mobile phone by wireless Bluetooth, and the data is received, displayed and processed by the Android mobile phone software developed by App Inventor. The software can also be used to identify vegetable oils in real time by using machine learning to analyze spectral data on Baidu's AI open platform. In the experiment, the spectrometer collected 600 sets of spectral data of six kinds of vegetable oils, and trained and tested these data by software. The accuracy of oil identification can reach 96.1% . The experimental results show that the spectrometer can identify the kinds of vegetable oil quickly and accurately by using the developed software. It has the advantages of simple operation, high sensitivity, low cost and no pollution to the sample, it has a good application prospect in the field of food safety rapid detection.
In this paper, a novel portable instrument for non-contact chlorophyll-b measurement is presented based on laser spectroscopy. In this instrument, a semi-conductor laser at the wavelength of 405 nm is selected as the excitation source. The laser power can be adjusted from 0 to 500mW at the pulsed repetition frequency (25Hz). The leaf excited by laser can generate chlorophyll-a fluorescence at the peak wavelength of 695 nm and chlorophyll-b fluorescence at the peak wavelength of 735nm. The fluorescence spectra can be received by our designed spectrometer with wavelength range of 400-780 nm and resolution of 2 nm. The chlorophyll-b in leaf can be obtained by analyzing the fluorescence intensity ratio F735/ F685. In experiment, we measured the spectra of chlorophyll-b in different epipremnum aureum leaves using our designed instrument at the distance of 5m., then calculated the corresponding fluorescence intensity ratio F735/ F685 of leaves, and established the correlation between chlorophyllb concentration measured by spectrophotometer and F735/ F685. The correlation coefficient value r2 is 0.84. The experimental results prove that our designed portable non-contact chlorophyll measurement instrument has the advantages of high detection speed, high accuracy and simplicity, which can be widely used in real-time chlorophyllb detection of leaf.
In this paper, a novel chlorophyll measurement system based on Y-type fiber is designed, and the chlorophyll value is obtained according to the intensity ratio of laser fluorescence-Raman signal produced by laser incident into water. In the system, a 405nm semiconductor laser is used as the light source. The laser is coupled into the delivering port of Y-type fiber and then transmitted into water. The generated scattered light, water Raman light and corresponding fluorescence are received and transmitted into spectrometer through the detecting port of Y-type fiber, and the chlorophyll can be obtained by analyzing the laser fluorescence-Raman ratio of water spectra. In experiment, we detect the chlorophyll standard solutions under a range of concentrations, and establish the correlation between chlorophyll concentration and fluorescence-Raman ratio (r2=0.98). In addition, the chlorophyll of natural water sample is measured with laser spectroscopy, the results of which are consistent with chlorophyll values obtained by traditional spectrophotometry. The experimental results prove that the chlorophyll detection method proposed in this paper has the advantages of high sensitivity, high precision, high detection speed and simplicity, which can be widely used in various water areas for real-time chlorophyll detection.
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