Full performance of optical H-K9L / BK7 glass

H-K9L is the Chinese made equivalent material of N-BK7. N-BK7 is the RosH compliance material of BK7. N-BK7 is a borosilicate crown optical glass.
VY choose the best grade of H-K9L glass from the biggest and famous glass manufacturer- CDGM.

H-K9L is a high quality optical glass used in lenses and other optical components where the additional benefits of Fused Silica are not required. It is a relatively hard material with extremely high homogeneity, low bubble and inclusion content. H-K9L has a low refractive index (≈1.52), low dispersion, and provides excellent transmittance through-out the visible and near infrared spectra, down to 350 nm in the ultraviolet.
Its good physical and chemical properties make it widely used in visible and near IR range. Most of windows, lenses and prisms, which used in laser, optical system, optical communication, are made from N-BK7/H-K9L glass.

Special properties of BK7/H-K9L
• high optical quality
• made of the purest raw materials
• colorless apperance and very clear looking
• nearly free of bubbles
• nearly free to inclusions

Typical applications
• protective windows for laser applications
• general optical applications
• optical items like lenses and prisms
• mirror substrates
• subtrates for optical coatings

H-K9L(N-BK7)composition: SiO2=69.13%, B2O3=10.75%, BaO=3.07%, Na2O=10.40%, K2O=6.29%, As2O3=0.36%.

Properties of H-K9L glass

Thermal Properties
Thermal Coefficient of Expansion(0/300°C)   70 X 10 -7/°C
Annealing Point  550°C / 1022 °F
Softening Point 719°C / 1326 °F
Strain Point 624°C / 1155 °F
Mechanical Properties
Density     2.51 g/cm3
Knoop Hardness   610
Young's Modulus     8.20 X 109 dynes/mm2
Poisson's Ratio     206
Optical Properties
Refractive Index     1.509
Chemical Properties
Hydrolytic Resistance     class 2
Acid Resistance  class 1
Alkali Resistance   class 1


Optical transmission in the VIS of K9 glass




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