Long range detection and recognition of IR upconversion material Y₂O₂S:Yb,Er

In order to propel the application of infrared up-conversion materials at long distance, the detection and recognition of the Ytterbium Erbium co-doped Yttrium Oxysulfide(Y2O2S:Yb,Er) were explored. The Y2O2S:Yb,Er material with an 1.5 m peak absorption and a 980 nm peak emission was prepared through an improved sulfur melting method, and was coated on a 900 mm900 mm aluminum plate to form a target. Due to the fact that the prepared material has a relative low conversion efficiency and a long fluorescence radiating period, which tends to broaden the exciting laser pulse, the target was then excited by a laser pulse of 1 550 nm wavelength, 8 ns pulse width and 5 mJ/pulse energy. The image of the target was collected by a BASLER camera with a 1 000 nm cutoff wavelength. A dedicated band pass filter with a 980 nm central wavelength and a 100 nm bandwidth was employed to suppress the interference caused by ambient light, realizing a higher signal to noise ratio. The excited spot was extracted from the acquired image of the target through simple frame differentiating image processing, so as to achieve far range detection and recognition. Test results obtained respectively at 50 m, 55 m, 60 m, 65 m, 70 m and 76 m indicate that the recognition rate reaches 98.3%.