Identification of Weakly Curved Substrates

LAYERTEC Marker Conventions of Weakly Curved Substrates

LAYERTEC applies a marker to the outer cylinder of weakly curved substrates. This allows a reliable identification of both sides. As shown below, the marker points to either the curved, the more weakly curved or the concave surface (depending on the general shape of the substrate). It is only applied for radii of curvature R > 1000 mm.

Table 1:LAYERTEC Marker Conventions of Weakly Curved Substrates

Substrates with a plane and a spherical surface	Substrates with two spherical surfaces	Substrates with two parallel spherical surfaces (Meniscus Lenses)

Marker points to the curved surface	Marker points to the surface with the larger radius of curvature (i.e. the weaker curvature)	Marker points to the concave surface

Visual Identification

Fig.2:Test grid for identifying the planar side and detecting the wedge of optical components

Finding the Plane Side

Hold optical element close to your eye.
Watch the reflection of the pattern in the optical surface (focusing to a long distance).
Reflected pattern is blurred → curved side is up
Reflected pattern is clear → plane side is up

Fig.3:Sharp, undistorted reflection of the test grid indicates the planar side of the optics

Is the Substrate Wedged?

Watch pattern through optical element.
Rotate optical element around surface normal.
Pattern shifts with respect to surrounding area → optical element is wedged
No shift → no wedge is present

Fig.4:A laterally shifted double reflection of the test grid indicates a wedged optical element