This is a high-quality dielectric mirror from Altechna, designed for use in the 900-1200nm wavelength range. The mirror, which is 25.4mm in diameter and 6mm thick, is made from N-BK7 Schott, a popular optical glass known for its excellent optical properties.
The mirror's coating is a broadband anti-reflection coating, specifically 'alt 900-1200 aoi 45', which is designed to reduce reflection and increase transmission. This coating is applied to the front surface of the mirror. The mirror's shape is that of a thin lens, which is often used in optical systems to reduce weight and thickness while maintaining optical performance.
The mirror is currently in stock and available for immediate purchase. For more information, please refer to the vendor's website at https://www.altechna.com/products/hr-broadband-mirrors/.