In laser diode systems, difficulties with spherical aberration correction are compounded by the beam’s high divergence angle. Since individual spherical lenses can refract light at only small angles before spherical aberration is introduced, three or four elements are often required to collimate laser diode light. In contrast, a single aspheric lens collimates without introducing spherical aberration.
When coupling light into fiber, it is often necessary to focus the laser light to a diffraction-limited spot. Typically, single spherical elements are not capable of achieving such a small spot size; spherical aberration is the limiting factor rather than the diffraction limit. In contrast, the aspheric lenses are corrected to eliminate the spherical aberration, and therefore, only diffraction limits the size of the focal spot.
Thorlabs mounts molded glass aspheres into stainless steel lens cells that are engraved with the part number for easy identification. These mounted aspheres have a typical metric thread that effortlessly integrates into your setup or OEM application. The mounted aspheres are readily adapted to our SM1 series of lens tubes by using ourAspheric Lens Adapters.
Mounted aspheres can replace a multi-element microscope objective by combining the lens with our Microscope Objective Adapter Extension Tube.
Unmounted molded glass aspheric lenses, plastic aspheric lenses, and large-diameter aspheric lenses are also available. The damage threshold for these lenses is determined by the antireflective (AR) coating. As a guideline these coatings can withstand 100 W/cm2 CW input power or 0.1 J/cm2 with 10 ns pulses energy at 1064 nm.
