Optical glass and ordinary glass, the main difference
   Optical glass with a high degree of transparency, a high degree of physical and chemical homogeneity as well as specific and precise optical coefficient.
    Physical properties of optical glass
    1: refractive index (ND)
    Refractive index glass elements are characteristic lines of sodium D = 589.3nm determination to ND said.
    2: The proportion (s)
    With the hydrostatic weighing method for determination of GDP.
    3: color value (x, y, Y)
    According to the International Commission on Illumination (CIE) 1931 and 1964 under way to determine a standard in the A and D65 illumination color values under the glass.
    4: Thermal characteristics
    5: When the glass temperature increases 1 ℃ relative variation of its length. Directory listed in the expansion coefficient α, were 20 ℃ ~ 30 ℃ temperature range of the average.
    6: The transition temperature (Tg)
    When the glass when sudden changes occur to expansion volume, namely the temperature corresponding to the transition temperature of the sample. The temperature near the glass viscosity 10 13 Pa. Seconds.
    7: softening temperature (Ts)
    When the physical properties of glass, dramatic changes in the amount of its expansion accounts also approaches zero temperature, that is, the glass softening temperature, then the viscosity of the glass close to 10 11 Pa. Seconds.
    8: Colour temperature conversion capacity (V)
    Rose color temperature and color temperature of glass falling from the two types of glass, color temperature glass composition, its ability to transform dense Bold (Mired) values to represent. L blue color temperature glass, grades for the SSB, with a negative value close Roeder. Lower color temperature

Amber glass, the density Bold is positive.
    The serial number is based on the color temperature glass density Bold values arranged. For example SSB130 that rose from the 3200K 5400K, its ability to transform negative 130Mired value rose color temperature glass. SJB130 that fell from the 5400K

3200K, its ability to transform the lower color temperature is 130Mired glass.
    Spectral characteristics of optical glass
    According to the spectral characteristics of colored optical glass can be divided into three categories
    2.1 cut-off glass
    Glass spectral curve in Figure 1. The spectral characteristics of indicators through the boundary limits of tolerance by the wavelength λtj provide wavelength transmittance Tλo and the slope of K, expressed in song.
    Wavelength boundary is defined by the provisions of the glass thickness, the spectral transmittance curve provides wavelength transmittance (Tλo) 50% Office of the wavelength limit set by the wavelength, and to λtj said.
    Tλo has indicated that the wavelength of the transmission ratio, is the spectral curve, the provision corresponding to a wavelength λo transmittance is also high transmittance curve.
    Spectral curve slope (K) is the required glass thickness to wavelength λtj-20nm and the Department λtj nm wavelength of light corresponds to the difference D to represent the password.
    K = Dλtj-20nm - Dλtj
    2.2 select glass absorption
    Only through the glass (or absorption) one (or several) in the wavelength range of light, see Figure 2. It is based on the provisions of the spectral characteristics of the glass thickness of the target in a specific wavelength λ Department and allow the transmission ratio through

Deviation of shot than that.
    2.3 Neutral glass
    Glass in the visible light of various wavelengths even without selective absorption, spectral transmittance curve shown in Figure 3, the spectral characteristics of targets based on the average transmittance Tp, the average transmission range than the allowable deviation △ Tp. Most

Large tolerance value expressed in Qz.
    Provisions of the average transmittance is thick glass in the wavelength range of the provisions of the glass every 20nm measured transmittance, on average, to Tp said.
    Average transmission range than the allowable deviation is the average of the grades of glass transmittance deviation allowed to △ Tp said.
    Means the maximum allowable deviation of the provisions of the glass in the wavelength range of the maximum deviation of the average transmittance transmittance transmittance ratio and the average absolute difference, to Qz said.