• Ø1" Positive Achromatic Doublet
• Focal Length: 40.0 mm
• Wavelength-Dependent Focal Length Shift Data for Each Doublet
• Surface Quality: 40/20 Scratch/Dig

Thorlabs' cemented Achromatic Doublets are computer optimized to provide excellent performance in the visible region. Our design for the achromatic doublets uses the helium "d" line (587.6 nm, yellow) and the hydrogen "F" (486.1 nm, blue/green) and "C" (656.3 nm, red) lines since these wavelengths reasonably represent the visible spectrum and are used to define the Abbe Number, V, of a material.

Achromatic doublets are useful for controlling chromatic aberration and are frequently used to achieve a diffraction limited spot when using a monochromatic source like a laser.

For best performance when collimating a point source with a positive focal length doublet, generally the first air-to-glass interface should have the greater radius of curvature (i.e., the flatter surface). Conversely, when focusing a collimated beam, the air to glass interface with the shorter radius of curvature (i.e., the more steeply curved surface) should face the incoming beam. When using a negative focal length achromatic doublet to diverge a collimated beam, the concave air-to-glass interface should face the collimated source.

• Design Wavelengths: 486.1 nm, 587.6 nm, and 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 Diameter
• 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 °C
• Diameter: 25.4 mm
• f: 40 mm
• f_b: 33.4 mm
• r₁: 23.66 mm
• r₂: -20.09 mm
• r₃: -57.68 mm
• t_c1: 10 mm
• t_c2: 2.5 mm
• t_e: 7.4 mm
• Materials: N-BK7/SF5
• Mounting Option: LMR1 with a SM1L05