Research On Portable Spectrum Measuring System Based On Smartphone

Nowadays,lighting and display devices are booming,and light-emitting devices such as LED lamps,VR devices,and television screens require related optical inspection.The most important detection device is the spectrometer.The spectrometer is used to measure the spectrum to obtain the optical parameters of the light source.Today’s mainstream spectrometers have the disadvantages of high price,large equipment,and cumbersome operation.The other small spectrometers also have problems of high price and inconvenient data processing.In daily life,portable spectrometer can be widely used in light source detection of lamps,food detection in supermarkets,etc.,but it is not actually popularized because of the high cost and big volume.In this paper,a portable system based on smartphone for spectrum measurement is developed for the shortcomings of existing spectrometers.The camera and CPU in the smartphone,which will reduce the hardware cost effectively,.take the replace of the detector and the host computer in the traditional spectrometer system.The image algorithm is used to solve the adaptation problem between different types of mobile phones and the measure device.The separation of image processing and measure device is realized,which is convenient to carry.The real-time field spectral measurement in different scenarios can be realized rapidly.The main content as follows:1.Design and build a smartphone spectrum measuring device.The device consists of an entrance slit,a plano-convex-lens,a reflective blazed grating,a cylindrical lens,and a standard whiteboard.The entrance slit is used to filter out stray light outside the target light source,the plano-convex-lens is used to collimate the incident light into parallel light,the blazed grating disperses the parallel light into monochromatic light,and the cylindrical lens amplifies the monochromatic light,and the standard whiteboard is used for imaging the dispersive images.By selecting components reasonably for optical path construction,the measuring device can provide a clear dispersion image of the target light source to the smartphone.2.Based on the Android smartphone operating system,write a mobile app that is compatible with the test device.The software integrates camera parameter adjustment,image processing algorithms,spectral calibration algorithms,spectral data display,file storage,parameter settings and more.The camera parameters are adjusted to control the focal length,exposure,color temperature and other parameters of the smartphone camera to obtain accurate spectral images.The image is cropped by Gaussian filtering,canny edge detection,gradient algorithm and morphological operation in OpenCV,and the image is determined by the spectral calibration algorithm.The correspondence between pixel points and wavelength intensity.Finally,the spectral curve can be displayed and stored.3.Perform spectral tests on three common illumination sources:in-line LED,cool white LED,and warm white LED,and compare the results with the results measured by the IS spectrum test system.The spectral curves are basically consistent,and the luminosity parameters are luminosity.Compared with the measurement results of IS system,the maximum deviation of correlation color temperature is 2.5%,the maximum deviation of color index is 9.8%,the maximum deviation of color coordinate x is 0.0074,the maximum deviation of color coordinate y is 0.0259,and the maximum deviation of relative integral intensity is 9.8%.It shows that the spectrometer based on smart phone can meet the needs of spectral measurement in mobile environment.