Writing and displaying by the laser on a long lag phosphor material

Abstract

We make a machine that can perform as an invisible hand able to write and draw smoothly accompanied with the incidental music. And this machine can be used in the commercial advertising display, artmobile poster writing, the accessory equipment of the multimedium classrooms, stage effect, new art pattern especially in dark. We present a new display application of the long lag phosphor (LLP) material in this paper. A prototype is fabricated which can be written, drawn and displayed by controlling a laser beam on the screen which is made from the LLP material. For selecting the match laser beam wavelength for different LLP material screens, the energy band structure of the LLP material Mn(H2PO4)2 of 3-4 eV band gap is calculated by VASP (Vienna abinitio simulation package) software and its Raman shift peaks of Mn(H2PO4)2 are tested at 625 nm, 769 nm, 1049 nm and in far infrared wavelength range. The intensity of powdery LLP SrAl2O4: Eu2+, Dy3+, which is tested by the instrument of UWLA(ultra-weak luminescence analyzer), can decay from 43479 to 9570 electronic counts in 5 min, and then descend slowly. The intensity decay of coated film LLP Mn(H2PO4)2, which is tested by the instrument of HANDYSCOPE HS3, can decay quickly at the beginning and then slowly after 400s. These intensity decay results can explain that LLP materials of SrAl2O4:Eu2+, Dy3+ and Mn (H2PO4)2 are suitable for displaying the image by our prototype. A prototype is successfully made by our group for writing English and Chinese words and drawing picture. Arduino Board is used to control two step motors, and X mirror and Y mirror are rotated to reflect the laser beam. An excitation dot is formed on the surface of LLP display screen. By drawing vectorgragh with Coreldraw and convert it into .nc file, the computer runs G-code in CNC (computer numerical control) automatically. Arduino controlled mirror rotation drives the laser beam. The trace of the laser dot is left on the screen and becomes article or graphs in afterglow. The whole device can be energy saving, eyes comfortable, low cost and easy to pick up.