Abstract: Disclosed are a preparation method for manganese-doped red phosphor, a device and a backlight module including the product. The method includes: 1) mixing A2BF6 polycrystalline particles with mill balls; 2) mixing A2BF6 powder obtained after ball-milling with a hydrofluoric acid for secondary crystallization; 3) filtering out solid particles in A2BF6 and hydrofluoric acid solution after the secondary crystallization; 4) performing ion exchange between A2BF6 particles and A2BF6; and 5) filtering out solid particles to obtain a filter cake, and performing drying treatment to obtain manganese-doped red phosphor.

Abstract: Measuring refractive index of air based on laser synthetic wavelength interferometry. The Apparatus includes a dual-frequency laser that emits orthogonal linear polarized light of wavelengths ?1 and ?2, a beamsplitter, two polarizing beamsplitters, two corner-cube retroreflectors, a quartz vacuum cavity of length L disposed in the measuring optical path in parallel to the light propagation direction, and two detectors. The apparatus is used to measure the refractive index of air using the dual-frequency laser to emit orthogonal linear polarized light with wavelengths ?1 and ?2, using the beamsplitters, corner-cube retroreflectors, quartz vacuum cavity, and detectors. The integer N and fraction ? of interference fringes of wavelength ?2 are determined. The refractive index of air n is obtained by using the length L of the vacuum cavity, integer N and fraction ? of the interference fringes of wavelength ?2.

Abstract: The present invention discloses a method and an apparatus for measuring the refractive index of air based on the laser synthetic wavelength interferometry, wherein a laser synthetic wavelength interferometer comprises a dual-frequency laser, a beamsplitter, a first polarizing beamsplitter, a second polarizing beamsplitter, a first corner-cube retroreflector and a second corner-cube retroreflector; a quartz vacuum cavity is disposed in the measuring optical path in parallel to the light propagation direction; when the measurement is performed, air is introduced into the quartz vacuum cavity until it is consistent with outside environment; the variation of the refractive index of air inside the cavity will cause change of the interference signal of the wavelength ?2; the first detector of photoelectric type is used to directly detect the integer N of the interference fringes of the wavelength ?2; then the first corner-cube retroreflector is moved to make the phase difference between the interference signals of