These microlenses are very small lenses made from high index optical glass, for a variety of miniaturisation applications. They are ideal for coupling fibres and laser diodes. Diameters are available down to 0.06 inches, focal lengths to less than 2mm. The micro lenses come in plano convex, plano concave, biconvex, biconcave and micro prism standard shapes. The lenses are precision polished to high tolerances (λ/2 surface figures), enabling them to be mounted into complex imaging systems. These lenses are supplied uncoated and can be mounted into aluminium housings on request.
These aspheric lenses are manufactured by precision moulding of optical crown glass. Aspheric surfaces permit a higher degree of correction than spherical surfaces. This gives improved performance from a simple, single element lens. These microlenses are corrected for use with a standard laser diode window and are primarily intended for the collection and collimation of laser diode radiation. The lenses have diffraction limited performance at any wavelength in the laser diode spectrum and can be Anti-Reflection coated upon request. A mounting flange is built in to the lens, which removes the need for costly and inconvenient mounting cells.
Microspheres are ideal for coupling light in or out of fibres, and for relaying images in compact areas. The focal point of a sphere is close to its surface. The sphere can be placed in contact with fibre or another sphere for almost perfect coupling. Three different coatings are available. All are single layer MgF2 coatings optimised for the visible range or either of the two diode laser bands. Coated microspheres require you to maintain the coating axis when in use. This axis is marked with a removable black dot for ease of location.
Gradient Index Microlenses
These microlenses are constructed from optical glass with a refractive index gradient. The material used in these microlenses has a radial index gradient. Focusing occurs within the material. The index variation is defined and normally specified by the constant √ A. The simplest form of gradient index lens is a cylinder. Collimated light incident on one end of the lens is focused as it travels along the length of the cylinder. These microlenses are particularly useful for fibre and diode coupling. They can be mounted in close proximity to the source. Gradient index microlenses with plano end faces and in a convex configuration for greater imaging power are available. The convex lenses have a spherical radius on one end only.
Normally these lenses are a quarter pitch and focus a collimated input at the remote face of the lens. However, we also offer lenses with slightly less than 1/4 pitch that focus just outside the lens. This is convenient where contact with the source or detector is physically impossible.
The lenses are wavelength specific (633nm, 830nm, 1300nm and 1560nm) and are Anti-Reflection coated for these wavelengths. Used at other wavelengths, focusing characteristics will vary from the published figures and the coatings will not be optimised.
Gradient Index Imaging Microlenses & Gradient Index Relay Microlenses
Gradient index imaging microlenses are optimised for imaging applications. They form an image at one face of the lens of an object at a working distance of 5mm from the opposite face of the lens. This image may be viewed directly by a 100X microscope or transferred to the distal end of a coherent fibre bundle or gradient index relay lens. The lenses are supplied uncoated and no coatings are offered.
A gradient index relay microlens is a rod formed from gradient index glass. The length is equal to an integral number of pitches. An image formed on one end of the lens is transferred to the remote end from where it may be viewed or transferred to another medium. These are used in rigid endoscopes and other applications that require the transfer of images. They are ideal for use with the gradient index imaging micro lenses.