Design Of Color-changing Anti-counterfeiting Glass With Adjustable Excitation Frequency

Due to the growing need for anti-counterfeiting,color regulation of luminescent materials has become a popular direction.Toning is generally done by changing the doping,concentration,composition of the material,and multi-wavelength light excitation.But these methods are easy to be repeated.In order to solve the problem of being able to change the emission color of rare earth doped fluorescent glass by simple and practical means,make better use of glass materials for encryption,and expand the application of fluorescent glass in the field of pattern anti-counterfeiting,this article is based on the technology of excitation source frequency regulation,systematically the rare earth doped fluorescent glass was designed under the excitation of 980nm laser with three signals of pulse wave,square wave and sine wave,and the emission color of the glass was adjusted.The influence of the frequency of the excitation source,the types of excitation signal and the power of the excitation source on the discoloration performance of glass were discussed.The specific research content of this paper is as follows:In the first chapter,the introduction introduces the main types and applications of rare earth dopedfluorescent glass,common color control methods for rare earth doped fluorescent materials,and the research progress of rare earth doped fluorescent glass in the field of anti-counterfeiting.In the second chapter,in order to solve the limitations of common methods for color adjustment of rare earth doped fluorescent glass and expand the application of glass in higher-end pattern anti-counterfeiting,a method of adjusting the frequency of the excitation source at 980nm is proposed to adjust the luminous color of the glass.SiO₂-PbF₂ based fluorescent glass was prepared by high temperature melting method.Design the fluorescent glass to study the fluorescence spectrum of the glass under three excitation modes with variable frequency and two excitation sources with different powers.Reflect the color change process of the glass by calculating the ratio of the fluorescence intensity of the green and red emission of the glass.The results show that the frequency and power of the excitation source will not affect the position of the glass emission band,but will change the ratio of the green and red fluorescence intensity of the glass,and the color of the glass will eventually change from yellow-green to yellow.When using a sine wave laser for frequency control,it was found that low-frequency control can make the glass color change more obvious.The different populated rates of the Er³⁺emission state are proposed to explain the glass color adjustment mechanism,and the glass powder is printed on the school badge using screen printing technology to achieve the effect of applying the glass to pattern anti-counterfeiting.In the third chapter,using the energy transfer between Er³⁺and Yb³⁺,we adjust the frequency and power of the three modes of excitation source,and study the influence of different excitation modes on the color adjustment of fluorescent glass.SiO₂-BaF₂-Zn F₂ based fluorescent glass was prepared by the high-temperature melting method.By adjusting the excitation frequencies of 1V and 2V 980nm pulsed laser,square wave laser,and sine wave laser,respectively,based on the fluorescence intensity ratio method,the influence of light excitation of three variable frequency excitation sources on the color of glass emission is discussed.Based on the color coordinates,it is found that the frequency control under the three excitation modes can change the color of the glass from yellow-green to yellow.Under the influence of the pulse wave with variable frequency,the color of the glass slowly approaches white,reflecting the superiority of the pulse wave excitation mode on the glass color adjustment.By comparing the color coordinates,it is found that the low-frequency control has better effect under the three excitation modes,and the color of the glass is stable at yellow under the high-frequency control.It is proposed that the different populated process of Er³⁺emission state affects the emission color of glass,high-frequency excitation promotes red emission and low-frequency excitation enhances green emission.According to the discoloration performance of the glass,the glass is suitable for application in the field of pattern anti-counterfeiting by adjusting the frequency of the excitation source.In the fourth chapter,based on the energy transfer between Ho³⁺and Yb³⁺,with the adjustment of the frequency and power of the three modes of excitation source,the effect of different excitation modes on the color adjustment of fluorescent glass is studied.Te O₂-WO₃ based fluorescent glass was prepared by high temperature melting method.Based on the fluorescence intensity ratio,it is found that under the excitation of pulse wave laser with variable frequency,the color of glass changes from yellow-green to yellow and the range of color change is greater under low-frequency control,while the glass color is concentrated in the yellow area under high-frequency control.When the frequency of the square wave is used to control the excitation,the change of the glass color is not obvious,and the color is relatively stable.The situation is special in the sine wave mode.In the 1V sine wave frequency control,it is found that the green emission intensity of the glass is very weak,and the red emission is almost absent.After trying to switch to a 2V sine wave,the glass color can also change from yellow-green to yellow and the range of changes is relatively large.On the whole,pulse wave excitation is more suitable for modulating the color of glass.The different populated processes of the main radiation states of the green and red radiation produced by Ho³⁺are proposed to clarify the principle of adjustable glass color.The glass powder is printed on the school badge by screen printing technology to realize the application of glass in pattern anti-counterfeiting.