This is a 25.4 mm diameter Germanium Flat Window, offered by Alkor Technologies. The window, which has a thickness of 6mm, is uncoated, providing a clear, unaltered view of the spectrum it is designed to transmit.
Germanium is a popular material for optical windows due to its wide transparency range, which extends from the ultraviolet to the far infrared. This particular window is designed to transmit light at a wavelength of 10600 nanometers, making it suitable for a range of applications in the mid-infrared spectrum.
The window is of the 'flat window' type, which means it is designed to provide a clear view without any distortion. The 'thin lens' shape further ensures that the window does not introduce any spherical aberration or other optical distortions.
For more information about this product, including pricing and availability, please refer to the vendor's website at http://www.alkor.net/germanium_windows_catalog.html.