A plano-concave lens has one concave surface and one flat surface, with a negative focal length. It is commonly used for beam collimation, increasing (or decreasing) focal length, or expanding (or reducing) images. To minimize spherical aberration, when the incident beam is collimated, it should be directed onto the concave surface of the plano-concave lens. Calcium fluoride (CaF₂) exhibits high transmittance in both ultraviolet and infrared spectral ranges, along with an extremely high damage threshold, making it widely used in the excimer laser industry. Calcium fluoride has a relatively low refractive index, ranging between 1.35 and 1.51 within the working wavelength range of 200 nm to 8.0 µm. Additionally, calcium fluoride demonstrates excellent chemical inertness and, compared to similar materials like barium fluoride (BaF₂) and magnesium fluoride (MgF₂), it also possesses high hardness characteristics. LBTEK also offers Plano-Concave Lenses made of N-BK7, N-SF11, and UV-grade fused silica. N-BK7 is the most commonly used material for high-quality optical components and is widely applied in visible and near-infrared applications. N-SF11 features a low Abbe number and high dispersion, while UV-grade fused silica provides high transmittance in the ultraviolet spectrum. In addition to uncoated plano-concave lenses, LBTEK also provides Calcium Fluoride Plano-Concave Lenses with anti-reflection coatings optimized for the 1.65 μm–3.0 μm range. All our lenses undergo precision machining and strict quality control to ensure that LBTEK delivers High-Quality Lens Products at reasonable prices.