• Ø2” mm Mounted Positive Visible Achromatic Doublets
• AR Coated for the 400 - 700 nm Range
• Engraved Threaded Housing Includes Part Number, Focal Length, and Coating
• Housing Enables Easy Integration into Thorlabs' Optomechanics
• Focal Length: 400 mm
• Surface Quality: 40/20 Scratch/Dig

Thorlabs' most popular cemented visible achromatic doublet is now available pre-mounted in engraved threaded mounts, making it easy to incorporate into your setup. The engraving on each mount clearly indicates the part number, focal length, antireflection coating deposited onto the surface, an arrow indicating the direction of light propagation to collimate a point source, and an infinity symbol denoting that this lens has an infinite conjugate ratio (i.e., if a diverging light source is placed one focal length away from the flat side of the lens, the light rays emerging from the curved side will be collimated).

This achromatic doublet, which is designed for use in the visible spectral region (400-700 nm), is computer optimized at infinite conjugate ratios. The design wavelengths used are the helium "d" (587.6 nm, yellow), hydrogen "F" (486.1 nm, blue/green), and hydrogen "C" (656.3 nm, red) lines since they reasonably represent the visible spectrum and are used to define the Abbe Number, V, of a material.

• Design Wavelength for Visible Doublet: 486.1 nm, 587.6 nm, 656.3 nm
• Diameter Tolerance: +0.00/-0.10 mm
• Focal Length Tolerance: ±1%
• Surface Quality: 40/20 Scratch/Dig
• Spherical Surface Power 3?/2
• Spherical Surface Irregularity: ?/4
• Centration: =3 arcmin
• Clear Aperture: >90% of Dia.
• A Coating Range: R_avg < 0.5% (400 - 700 nm)
• Damage Threshold 0.5 J/cm² (532 nm, 10 ns pulse, 10 Hz, Ø0.566 mm)
• Operating Temperature: -40 to 85 ^oC
• Lens Dia.: 50.8mm
• f: 400.0mm
• f_b: 396.1mm
• r₁: 219.8mm
• r₂: -186.75mm
• r₃: -760.0mm
• t_c: 5.0mm
• t_c2: 2.0mm
• t_e: 5.1mm
• Materials: N-BK7/SF2
• Mounting Thread: SM2 (2.035"-40)