The hottest laser holographic fluorescent anti-cou

2022-09-25
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Laser holographic fluorescent anti-counterfeiting film and its application

in recent years, with the increasing prosperity of the economy, fake and shoddy goods have also been emerging. In order to make huge profits, a few people forge not only trademarks, invoices, certificates, lottery tickets, but also valuable securities such as RMB and credit cards. It has brought great harm to people's life, social security and national interests. In order to crack down on current criminal activities, we summarize the experience of case investigation and briefly introduce the method of identifying forged lottery tickets with extreme red fluorescence

I. principle

extreme red fluorescence refers to the use of ultraviolet light or visible light with a shorter wavelength (the wavelength range is 400 ~ 560 μ m) To excite the light source to irradiate the sample, the emitted fluorescence wavelength is 650 ~ 800 μ The fluorescence of M is called extreme red fluorescence. Human eyes are particularly insensitive to light in this area, and generally cannot see clearly or completely. To observe the extreme red fluorescence, the following conditions must be met:

1. The excitation light source must have a wavelength of 400 ~ 560 μ Blue light or yellow green light between M

2. Instruments that can observe infrared light must be used. Industry experts generally believe that the receiving wavelength should be in the range of 650 μ M or more away

3. a dark red filter must be added to the receiver

II. Operation method

place the tested object under yellow and green light, and the sample immediately emits extremely red fluorescence. This fluorescence is received by the camera lens, and the light signal is converted into an electrical signal to be reflected in the form of an image. A bright white image can be seen on the black-and-white monitor

III. case introduction

in 1993, the lottery issuance center sent two suspected forged lottery tickets and ten standard lottery tickets. Ask to identify the authenticity of lottery tickets. Observed under natural light, there is no obvious difference between the two lottery tickets for inspection and the 10 standard lottery tickets in paper quality, plate making, printing pattern, number, etc., but after technical identification, it is found that there is a significant difference between the two lottery tickets for inspection and the 10 standard lottery tickets

(I) appearance observation

the size of the two lottery tickets submitted for inspection is slightly different from that of the 10 standard lottery tickets. The length and width of the 10 standard tickets are uneven, and the relative error is generally ± M. The length and width of the two tickets submitted for inspection are uneven, and the size difference between the two tickets is 0.7mm. The difference between the two long sides of one lottery ticket is 0.3mm

(II) long and short wave ultraviolet observation

the two lottery tickets tested were observed under ultraviolet light, and the front was yellow as a whole, without fluorescence, and the dye on the back was orange fluorescence. The front of the 10 standard lottery tickets is blue and white fluorescent, and the dye on the back is purplish red fluorescent. There are obvious differences between the two lottery tickets tested and the 10 standard lottery tickets under the UV lamp

(III) ef-250 image compositor inspection

if it is two identical samples, all patterns, patterns and numbers on the image compositor should be able to coincide. However, the number 090d of the two lottery tickets submitted for inspection can coincide with the same number spacing, but compared with the standard lottery tickets, the number spacing cannot coincide completely

(IV) observe with the extremely red fluorescence method

place the two tested lottery tickets and 10 standard lottery tickets under yellow and green light successively, and the lottery tickets have different effects at this time. The twelve zodiac patterns of 10 standard lottery tickets emit strong extremely red fluorescence, and the patterns are clear and complete. However, the twelve zodiac patterns of the two lottery tickets submitted for inspection do not emit extremely red fluorescence. The twelve zodiac research group learned from the research of surrounding provinces and cities that the zodiac patterns are ambiguous

after the test of the above method, there is a very obvious difference between the two lottery tickets submitted for inspection and the ten comparison lottery tickets, which shows that the two lottery tickets submitted for inspection are forged

many cases have proved that the extreme red fluorescence method is accurate and reliable. It can not only identify forged lottery tickets, but also play a great role in the identification of blurred handwriting, concealed handwriting and altered cheques. In particular, if this technology is applied to anti-counterfeiting encryption products, it will be a promising encryption technology

scope of application:

"trademarks, invoices, certificates, lotteries, RMB, credit cards and other securities

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