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Colored optical filter glass
 
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Group names and classification

According to the colour, application and the first alphabet of the Chinese Phonetic alphabet of glass, we named and classified the colored optical filter glasses. There are 20 groups and 117 types glasses.
The glasses can be classified into three categories based on their spectral transmission curves.

Cut-off type colored optical filter glass
The glass is named bases in spectral characteristic of which is represented by the wavelength transmission limit. For example, if the transimission limit of glass is 490nm, then it is named as JB490, there are five groups and 35 types glasses.

Selective absorption colored optical filter glass
This part of the glasses can be divided into 14 kinds and 78 types bases on the color and application. The types are arranged in accordance with serial numbers, which have no special meaning.

Neutral filter glass
They are named based on the average tranmissivity characteristics in 400nm to 700nm wavelength with 2nm thickness. For example, if the average transmissivity of a 2nm thick sampler is 70%, then it's named as ZAB70. And there are ten types of glasses in this part. But three types of them(ZAB65, ZAB30, ZAB5)are tested in 440nm~660nm wavelength.

Spectral transmittance characteristic

Glasses exhibiting a filtering characteristic can be divided into three classes.

Cut-off type colored optical filter glass
The spectral tranmission curve of this kind of glass is shown in Fig.1 and the spectral characteristic index of which is represented by the wavelength of transmission limit (ltj), the allowable deviation of transmission limit, the slope of absorption curve(k) and the minimum transmisivity of the specified wavelength, etc.
The wavelength of transmission limit (ltj) if defined as a wavelength which corresponds to 50% of the maximum transmissivity of a certain wavelength l0 also with a definite glass thickness.

The slope of absorption curve is represented as the difference between light densities Dltj-20(nm) and Dltj of wavelength ltj(nm) as follows with a definite glass thickness

K=Dltj-20 - Dltj
Selective absorption colored optical glass
This kind of glass only transmits (or absorts) light within the range of one (or several) wavelength(s) as shown if Fig.2, and the spectral characteristic index of which is represented by the values of tranmissivity and allowable deviation of transmissivity at specified wavelength l with a definite glass thickness.
Neutral filter glass
It absorbs uniformly without selecting the light of different wavelength from a visible light. The spectral transmission curve is shown in Fig.3 and its spectral characteristic index is represented by values of the average transmissivity Tp, the allowable deviation range of average transmissivity ΔTp and the maximum allowable deviation Qz.
The value of average transmissivity which is measured in a 2mm thick glass at intervals of 20nm between specified wavelength range.
The allowable deviation range of average transmissivity ΔTp indicates the deviation allowed for the average transmissivity of the specified designation of glass.
The value of maximum allowable deviation Qz indicate the absolute differences between the average transmissivity and the maximum transmissivity differed from the average transmissivity within specified wavelength for different designation of glass.
 

Physical properties

Refractive index(ND)
The refractive index of glass is determined with the character spectrum of sodiunm(Na) in D=589.3nm and it can be expressed by ND.

Density(S)
Hydrostatic balance method is used to determine the glass density.

Colour coordinate value (x, y, Y )
The value is measured according to the method provided by International lighting Committee in 1931 and 1964.

Thermal properties

1.Linear thermal expansion coefficient
The coefficient of the linear expansion give the relative change in length of a glass sample when heated by ine centigrade. All of the coefficient here are the average values of linear extension coefficients in 25oC~300oC.

2.Transformation temperature (Tg)
The transformation temperature is determined as the elongation of the glass is rapidly changing. And the viscosity corresponding to this temperature is 1013Pa-s.

3.Softening temperature(Ts)
When the physical property of glass has been greatly changes and its elongation is approaching to "zero" , as well as its viscosity is 1011Pa-s, the corresponding temperature is definited as softening temperature.

The transformation ability of color temperature(v)
There are two kinds of color temperature glass(SSB). The SJB is amber in color and the SSB is blue.
The division and their serial number is determined by their Mired values. For example, glass-SSB130 can turn the color temperature from 3200K to 5400K. And its transformation ability is -130 Mired. On the contrary, the glass-SJB130 can turn the color temperature from 5400K to 3200K, and its transformation ability is +130 Mired.

 

Chemical stability

The chemical stability represented by water durability(Dw) or acid durability(DA) is measured with powder according to the standard test method of glass chemical durability provided by Japan Optical Glass Industry Society.