Custom Freeform Optics

12 Aug 2024

Types of Aspheric Lens

An aspheric lens may have any of a number of geometries. Most aspheric lenses are rotationally symmetric but have a more complex front surface. Unlike a spherical lens, the curvature changes with the distance from the optical axis. Another way of putting this would be to say that the radius of curvature varies radially from the center of the lens.

Typically, the further from the optic axis, the weaker the curvature. A lens that does not have these symmetries is typically called a free-form optic.
Aspheric lenses are defined by their surface profile (sag of the surface parallel to the optical axis) or by means of orthogonal coefficients Q_bfs and Q_con. Q_bfs quantifies the RMS slope departure of your aspheric lens from a best fit sphere, and Q_conquantifies the sag departure from a base conic.

Avantier's Aspheric Manufacturing Capabilities

Diameter	5 – 200mm
Diameter Tolerance	+0/-0.100mm – +0/-0.010mm
Asphere Figure Error (P – V)	3μm – smaller than 0.06μm
Vertex Radius (Asphere)	±0.5% – ±0.05%
Sag	25mm max
Typical Slope Error	1μm – 0.15μm per 1mm window
Centering (Beam Deviation)	3 arcmin – 0.5 arcmin
Center Thickness Tolerance	±0.100mm – ±0.010mm
Surface Quality (Scratch Dig)	80-50, 40-20,10-5
Aspheric Surface Metrology	Profilometry (2D &