• Material: N-SF11
• Wavelegnth Range: 1050-1620 nm
• C-Coated
• Diameter: Ø25.4 mm
• Offers Better Chemical Resistance than N-BK7

The Plano-Concave lens, which is fabricated from N-SF11 glass, is C-Coated (1050-1620 nm). The coating greatly reduces the 4% loss per surface incurred when using an uncoated lens.

N-SF11 glass, a RoHS complient version of SF11, is most commonly used in harsh environments since it is inert to biological degradation and resistant to naturally encountered chemicals, alkalis, and acids. With an uncoated wavelength range of 420 nm - 2.3 µm, N-SF11 also offers a usage range that is slightly shifted to the red compared to N-BK7, which is our RoHS-compliant BK7 glass and has an uncoated wavelength range of 350 nm - 2.0 µm. Since N-SF11 glass has a lower Abbe Number than N-BK7 glass (25.76 compared to 64.17), it is associated with more dispersion.

Like all plano-concave lenses, this lens has negative focal lengths and can be used to diverge collimated beams. In this case, the curved surface of the lens should face the source to minimize spherical aberration. In addition, it can be employed to offset the effects of spherical aberration caused by other lenses in an optical system.

• Lens Shape: Plano / Concave
• Material: N-SF11
• Wavelength Range: 1050-1620 nm
• Design Wavelength: 587.6 nm
• Index of Refraction: @ 633 nm 1.778
• Abbe Number: v_d=25.76
• Surface Quality: 40-20 Scratch-Dig
• Surface Flatness: (Plano Side) ?/2
• Spherical Surface Power: (Concave Side 3?/2
• Surface Irregularity: ?/4
• Centration: =3 arcmin
• Clear Aperture: >90% of Diameter
• Focal Length Tolerance: ±1%
• Diameter: 25.4 mm
• f: -30 mm
• R: -23.4 mm
• t_c: 3.5 mm
• t_e: 7.3 mm
• f_b: -32 mm
• Suggested Mount: LMR1 and SM1L05