Aspherical Lenses - Optical Lenses: SCHOTT Advanced Optics

ASPHERES FOR SUPERIOR IMAGE QUALITY

Aspherical lenses have a complex surface profile. SCHOTT uses both CNC machining (Computerized Numerical Control) and MRF tooling (Magneto Rheological Finishing) techniques to manufacture these lenses in small and medium-sized quantities or for use in prototypes.

Due to their unique surface structure, aspherical lenses eliminate monochromatic aberrations (e.g. spherical aberrations) and therefore deliver superior overall image quality. They are being used to replace multi-spherical element assemblies more and more frequently because this reduces the total weight and enables a more compact design.

SCHOTT offers aspheres in various sizes and different materials and relies on two main polishing processes:

CNC machining and polishing

Precise pressing

These two basic polishing processes serve different products and markets:

	CNC machining and polishing	Precise pressing
Quantity	Prototypes, small to medium-sized quantities	Broadscale production
Market	Laser and industrial applications	Imaging and lighting applications
Advantages	High flexibility with design changes	High volumes
Glass type	All glass types, fused silica	Low Tg glass

Main advantages:

SCHOTT masters the entire value chain and leverages its reliable product portfolio to produce customized aspheres
Custom designed products of the highest quality
Flexible production – from a single piece to serial production
Customized polishing possible

Advantages of using aspheres:

Improvement of imaging quality
Reduction of construction size and depth
Reduced weight
Enhanced total light transmission
Easier assembly

Astronomy Consumer Optics Industrial Equipment Lithography Medical & Biotech Safety & Security

Please contact us for information on astronomy applications.
Specific customized solutions available.

Aspherical lenses are available as:

Supply Forms	Diameter
CNC-blanks polished coated	15 – 180 mm
Molded (low Tg glasses only)	1.5 – 35 mm

Materials Used

All types of optical glass
Fused silica
Other materials on request

Attributes	CNC Machining and Polishing			Molded (Low Tg Glasses only)
	Commercial	Precision	High Precision
	Diameter	15 – 180 mm	15 – 160 mm	15 – 140 mm	1.5 – 35 mm
Diameter tolerance*	± 0.1 mm	± 0.05 mm	± 0.02 mm	± 0.05 mm
Center thickness*	3 – 40 mm	3 – 40 mm	5 – 40 mm	0.5 – 10 mm
Radius of curvature convex*	> 10 mm	> 20 mm	> 30 mm	> 3 mm
Radius of curvature concave*	Upon request	Upon request	Upon request	> 5 mm
Tolerance on radius of curvature*	± 0.5%	± 0.1%	± 0.05%	± 0.5%
Surface flatness (PV, asph. side)*	2 μm	0.5 μm	0.2 μm	< 0.5 μm
Irregularity (PV, spherical side)*	1 μm	0.2 μm	0.1 μm	< 0.5 μm
Tilt from asph. side to other side*	< 6 arc min	< 3 arc min	< 1 arc min	< 1 arc min
Surface roughness – Rq*	< 5 nm	< 3 nm	< 1.5 nm	< 15 nm
Surface quality (scratch & dig) (5/NxA)*	60/40 5/6 x 0.25	40/20 5/3 x 0.25	10/5 5/3 x 0.025	40/20 5/3 x 0.16
Typical volumes*	From a single piece to series production			> 200 pcs

* Depending on the customer’s specifications. Please contact us.