• Material: N-BK7
• Wavelength Range: 650 - 1050 nm
• Spherical Surface Power: 3 Fringes
• Focal Length: -50.0 mm
• Spherical Surface Irregularity: λ/4

This Bi-Concave lens is fabricated from an N-BK7 substrate. This lens is available B-Coated. Bi-concave lenses have a negative focal length and are best used to diverge a converging beam. Similar to a plano-concave lens, a bi-concave lens can diverge a collimated beam to a virtual focus like in a Galilean-type beam expander.

• Lens Shape: Concave
• Material: N-BK7
• Wavelength Range (-B Coating): 650 - 1050 nm
• Design Wavelength: 587.6 nm
• Index of Refraction: 1.515
• Surface Quality: 40/20 Scratch-Dig
• Diameter Tolerance: +0.0/-0.1 mm
• Thickness Tolerance: ±0.1 mm
• Centration: ≤3 arcmin
• Clear Aperture: ≥90% of Diameter
• Focal Length Tolerance: ±1%
• Diameter: 25.4 mm
• f: -50.0 mm
• R: -52.0 mm
• Center Thickness t_c: 3.0 mm
• Edge Thickness t_e: 6.1 mm
• Back Focal Length f_b: -51.0 mm
• Suggested Mount: LMR1 and SM1L05