Overview: A special form of a thick biconvex optical lens is a ball lens,
usually having the geometrical form of a ball (sphere). They are
manufactured from a single material, usually an optical glass with
good transparency in the wavelength region of interest. A
frequently used material is fused silica. Ball lenses and can focus or collimate light, depending upon the
geometry of the input source. They are great optical components for
improving signal coupling between fibers, emitters, and detectors.
They are also used in endoscopy, bar code scanning, ball pre-forms
for aspheric lenses, and sensor applications. Ball lenses are usually made with relatively small diameters of a
few millimeters or sometimes even less than 1 mm (microlenses).
Particularly for such small dimensions, they are easier to
fabricate than lenses with traditional designs. Another variant are half-ball lenses, which are obtained simply by
cutting ball lenses in half. Half-ball lenses are also common and can be interchanged with full
ball lenses if the physical constraints of an application require a
more compact design. Star Optic provides ball lenses and half ball lenses made from
various substrate materials including sapphire, ruby, BK7, UV fused
silica, high index glass, and germanium, ZnSe, ZnS with AR coating. Available diameters are between 0.3 mm to 100 mm, with diameter
tolerance (sphericity) <0.3 µm and surface roughness (Ra)
<0.007 µm. Custom ball and half ball module options are also
available on request. There are five key parameters needed to understand and use ball
lenses: Diameter of Input Source (d)(d), Diameter of Ball Lens (D), Effective Focal Length of Ball Lens
(EFL), Back Focal Length of Ball Lens (BFL)and Index of Refraction
of Ball Lens (n). General Specifications of BK7 Ball Lens: Material | N-BK7 | | Diameter Tolerance | +0/-0.005mm | Surface Quality | 60/40 scratch-Dig | Sphericity | <0.003mm | Clear Aperture | >90% | Coating | None, Available |
Standard Products of BK7 Ball Lens: PN. | Material | Diameter (mm) | Coating | BAL0.3 | N-BK7 | 0.3 | Uncoated | BAL0.5 | N-BK7 | 0.5 | Uncoated | BAL1.0 | N-BK7 | 1.0 | Uncoated | BAL1.5 | N-BK7 | 1.5 | Uncoated | BAL2.0 | N-BK7 | 2.0 | Uncoated | BAL2.5 | N-BK7 | 2.5 | Uncoated | BAL3.0 | N-BK7 | 3.0 | Uncoated | BAL4.0 | N-BK7 | 4.0 | Uncoated | BAL5.0 | N-BK7 | 5.0 | Uncoated | BAL6.0 | N-BK7 | 6.0 | Uncoated | BAL8.0 | N-BK7 | 8.0 | Uncoated | BAL10.0 | N-BK7 | 10.0 | Uncoated |
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