INDUSTRIAL MANUFACTURING BLOG YOU SHOULD BE READING

What is N-BK7 ? What is H-K9L?

11 Feb.,2025

H-K9L and N-BK7 are both very commonly used optical materials with excellent transmittance from the visible to the near-infrared (350-2500nm). They have many of the same properties, can often be used in place of each other, have a wide range of applications in telescopes, lasers and other fields.

N-BK7 and H-K9L are borosilicate crown glasses commonly used in optical applications, they are mainly composed of silicon dioxide (SiO2) and boron trioxide (B2O3) , share many properties and can often be used in place of each other. N-BK7 is a product from Schott, Germany, used in a wide range of visible and short-wave infrared applications, H-K9L is a product from CDGM, is a high quality optical material commonly used in lenses for processing high-precision optics in the visible and near-infrared regions.

Characteristics

1. Excellent transmittance. It can effectively transmit light in the visible range and reduce the scattering and absorption of light. It is an ideal light-transmissive material, widely used in optical device manufacturing, optical instruments and optical lenses.

2. Low dispersion. Dispersion refers to the difference in the refractive index of the material to different wavelengths of light, N-BK7 and H-K9L both have high Abbe number, indicating that the dispersion is small, the colour correction performance is good, it can reduce the chromatic aberration of the light when passing through the surface of the optical elements and improve the imaging quality of the optical system.

3. High homogeneity of refractive index, it can be used to manufacture high-efficiency optical elements, such as prisms, lenses, for optical system focusing and imaging.

4. Few bubbles and low impurity content, so it is very suitable for manufacturing precision lenses.

5. Low coefficient of thermal expansion and good thermal stability, enabling it to withstand temperature changes without significant optical aberrations.

6. Good mechanical properties, high hardness and scratch resistance, able to resist a certain degree of external forces and wear and tear.

7. Chemical resistance, good resistance to many chemicals, which increases its service life in a variety of environments.

What is N-BK7 ? What is H-K9L?

Application

Photography and video: The transparency and dispersion properties of H-K9L(N-BK7) glass make it the material of choice for camera lenses and video equipment.

Laser System: In laser systems, it is used to manufacture optical components such as output windows and resonant cavity lenses.

Scientific research: H-K9L (N-BK7) glass is used extensively in scientific research, including satellite technology, imaging applications in astronomical applications, optical experiments and high-precision measurements.

Medical equipment: Used in medical optical equipment such as laser surgical instruments and optical microscopes.

Communication technology: Optical components for fibre-optic communication systems, ensuring high quality and speed in data transmission.

Comparison of H-K9L and N-BK7

H-K9L is a high-quality optical material commonly used in China to process high-precision optical components in the visible and near-infrared regions. It has the same performance as SCHOTT's N-BK7 and HOYA's BSC7 glass, with high uniformity, low bubble degree, good physical and chemical properties. H indicates that the glass is a safe and environmentally friendly glass in accordance with the EU ROSH directive, and does not contain lead, arsenic, cadmium and radioactive elements. H-K9L is more competitive in the market because it is cheaper than N-BK7.

Performance of H-K9L and N-BK7

Parameter	H-K9L	N-BK7
Refractive index nd	1.51680	1.51680
Abbe number vd	64.20	64.17
Density ρ	2.52 g/cm3	2.51 g/cm3
coefficients of thermal expansion α	7.6 10-6/K ï¼ˆ-30/+70â„ƒï¼‰	7.1 10-6/K ï¼ˆ-30/+70â„ƒï¼‰
Application	Lens,prism,flat mirror, other high precision optical components