FINISHED MINERAL LENS STANDARD ON POWER, PRISM & SURFACE

SINGLE FOCAL SPECTACLE LENSES

WITH UNFINISHED EDGES; REQUIREMENTS AND ADMISSIBLE TOLERANCES

1. Range of Application

This standard applies for single vision lenses made of non-organic and organic materials, which are used in spectacles for correction purposes. It does not apply for lenses, which have a prismatic power in the reference point.

2. Also applies for the following standards: DIN3l ( ISO8980-1 ); Name DIN; Association emblem DIN.

3. Requirements

3.1 Powers

The permissible deviations are referenced to the optical axis of the lenses.

1. Lenses with spherical power

3.1.2 Lenses with cylinder power

The spherical deviations apply also for both axes of cylinder lenses

Table 2

SPH Power Range dpt.		CYL Tolerances for Cylinder Power
		0.25 - 0.75	1 - 4	4.25 - 6	over 6
From 0 To -3	From 0 To +3	±0.09	±0.12	±0.18 *1	-
Under -3 To -6	Over +3 To +6	±0.12	±0.12	±0.18	±0.25 *2
Under -6 To -9	Over +6 To +9	±0.12	±0.18	±0.18	±0.25
Under -9 To -12	Over +9 To +12	±0.12	±0.18	±0.25	±0.25
Under -12 To -20	Over +1 To +20	±0.18	±0.25	±0.25	±0.25
Under -20	Over +2	±0.25	±0.25	±0.25	±0.25
*1. For lenses with powers from 4.25 to 4.00 cylinder, the tolerances in both axis are ±0.09 dpt. *2. For lenses with cylinder powers of more than 6 dpt, the tolerance in both axis is ±0.12 dpt.

2. Centering

Table 3

Power Range (dpt.)		Allowable deviation of the optical axis from the reference point (mm)	Allowable prismatic power for the deviation in the reference point (cm/m)
From 0.00 To -0.25	From 0.00 To +0.25	-	0.12
Under -0.25 To -2.00	From +0.25 To +2.00	3	-
Under –2.25	Over +2.00	2	-

3.3 Material arid Surface Errors

Lenses may not have within a diameter of 30mm, referenced to the optical center, any bubbles, imperfections, scratches, holes, etc., when inspected with bare eye. Outside this area small imperfections are allowable.

Inspection should be as described in 4.

3.4 Edge Condition

Some clips are allowed. The usable diameter may be up to 1mm smaller than the actual diameter.

4. Inspection

The material and surface inspection is done by a trained inspector visual subjectively without magnifying auxiliary equipment with following inspection set up.

Inspection is done at the light-dark zone.

*Refer to the diagram on Annex A

5. Marking

Lenses, which are according to this standard, may have on the package the emblem of the association DIN according to DIN3l together with the emblem of the manufacturer.

Q.C. Standard

First Quality Lens

65Ø	70Ø

1. Lens within diameter of 45mm in 65Ø and 50mm in 70Ø should not have any bubbles imperfections, scratches, holes.

2. Outside this area small imperfections are allowable.

3. Chips 0.5~1mm smaller than the actual diameter.

Annex A

Material and surface quality