BSN12 In Stock

The BSN12 by ThorLabs is a high-quality plate beamsplitter that is designed for precision optical applications. With a split ratio of 10:90 and a dielectric beamsplitter coating optimized for the 1.2 - 1.6 µm wavelength range, the BSN12 offers outstanding performance and reliability.

Constructed from UV-grade fused silica, the BSN12 boasts excellent transmission in the deep UV range, superior homogeneity, and a lower coefficient of thermal expansion compared to N-BK7. This makes it a top choice for applications spanning from the UV to the near IR. Furthermore, the BSN12 exhibits minimal laser-induced fluorescence, making it highly suitable for sensitive optical systems. Measuring Ø1" in size, the BSN12 offers long-term stability and durability. To mitigate unwanted interference effects, such as ghost images caused by reflected light from the front and back surfaces of the optic, the BSN12 features an antireflection (AR) coating on the back surface. This AR coating is specifically designed for the same operating wavelength range as the beamsplitter coating on the front surface, ensuring optimal performance.

By applying the AR coating to the back surface, the BSN12 reduces the percentage of light reflected from approximately 4% on an uncoated substrate to less than 1% over the entire operating range of the coating. Additionally, the back surface of the BSN12 has a 30 arcmin wedge that minimizes ghosting, ensuring that any reflected light diverges and does not affect the clarity of the optical system. For ease of identification and orientation, the edge of the BSN12 is engraved with the item number and an arrow pointing to the AR-coated, wedged surface. This thoughtful design feature simplifies integration into optical setups and enhances usability.