Plano-concave axicons have a plano surface in combination with a concave conical surface. They are made of optically transparent or filter materials with two polished surfaces, grounded edges and chamfers. An axicon made up of conical and flat surface produces a ring shaped image along the axis from a point light source. Due to the fabrication process, a central hole is needed to produce a concave conical surface. Hole diameter is typically 1 mm.
|Surface Figure||L/4 @ 632.8 nm|
|Surface Quality, scratch & dig||40-20|
|Apex Angle Tolerance, arcmin||+/-0.5|
|Clear Aperture, %||90|
|Design Wavelength, nm||633|
|Diameter Tolerance, mm||+0.0, -0.15|
|Thickness Tolerance, mm||+/-0.1|