Method for manufacturing a glass wafer of high quality, glass wafer, glass part element, stack, augmented reality device and use

1 . A glass wafer, comprising:

a first main surface; and

a second main surface opposite the first main surface, a material of the glass wafer having a refractive index N,

wherein, for each of a plurality of sub-domains of a maximal extension D of the glass wafer, the plurality of sub-domains are located within an effective domain of the glass wafer:

from a thickness distribution of the glass wafer between the first main surface and the second main surface of a respective one of the plurality of sub-domains, a specific angle E is configured for being determined, wherein the specific angle F is determined as an angle of a planar contribution to a change in the thickness distribution;

wherein the glass wafer has a maximal thickness of 2 mm or less,

wherein the glass wafer has a specific thickness t,

wherein the glass wafer is configured with respect to at least one parameter of the glass wafer such that for each of the plurality of sub-domains a local quality index LQI of the glass wafer is equal to or smaller than a threshold T, with the threshold T being defined as

T

=

ε

max

D

wherein ε max is 360 arcsec or less,

wherein the local quality index LQI is defined as:

LQI

=

❘

"\[LeftBracketingBar]"

ε

❘

"\[RightBracketingBar]"

t

⁢

N

2

-

1

.

2 . The glass wafer according to claim 1 , wherein at least one of:

(i) the refractive index N of the material of the glass wafer is at least one of (a) between 1.4 and 3; (b) 1.4 or more; and (c) 3 or less; and

(ii) the material of the glass wafer has the refractive index N for a wavelength of between 587 nm and 588 nm.

3 . The glass wafer according to claim 1 , wherein at least one of:

(i) a thickness of the glass wafer varies for each of two positions by at most 5000 nms; and

(ii) the maximal thickness of the glass wafer is at least one of:

(a) 1.9 mm or less;

(b) 0.01 mm or more; and

(c) between 0.01 mm and 1.8 mm.

4 . The glass wafer according to claim 1 , wherein each of the plurality of sub-domains at least one of:

(i) is or is configured for being defined;

(ii) includes at least one part of a body of the glass wafer between and inclusive of the first main surface and the second main surface;

(iii) includes at least one of (a) at least 0.1%, and (b) at most 80%, respectively, of a total glass material of the glass wafer;

(iv) is disk-like shaped;

(v) has a same said maximal extension D; and

(vi) includes in at least one cross-sectional plane a circular, an oval, or a rectangular circumferential shape.

5 . The glass wafer according to claim 1 , wherein at least one of:

(i) each of the plurality of sub-domains at least one of is of a disk-like shape, of a rectangular shape, and has a same said maximal extension relative to one another;

(ii) the plurality of sub-domains are at least partly overlapping relative to one another; and

(iii) the plurality of sub-domains cover at least one of:

(a) more than 50% of the glass wafer; and

(b) less than 99.9% of the glass wafer.

6 . The glass wafer according to claim 1 , wherein at least one of:

the maximal extension D of each of the plurality of sub-domains is a respective diameter of a plurality of disk-like sub-domains when the plurality of sub-domains is the plurality of disk-like sub-domains; and

the maximal extension D of each of the plurality of sub-domains is:

(i) 1 mm or more;

(ii) 100 mm or less; and

(iii) between 1 mm and 100 mm.

7 . The glass wafer according to claim 1 , wherein the effective domain at least one of:

(i) is or is configured for being defined;

(ii) includes at least one part of a body of the glass wafer between and inclusive of the first main surface and the second main surface;

(iii) includes at least one of (a) at least 10%, and (b) at most 99.99% a total glass material of the glass wafer;

(iv) is disk-like shaped; and

(v) includes in at least one cross-sectional plane a circular, an oval, or a rectangular circumferential shape.

8 . The glass wafer according to claim 1 , wherein the specific thickness t is a minimal thickness, the maximal thickness, and/or a mean thickness of the glass wafer.

9 . The glass wafer according to claim 1 , wherein the planar contribution is determined by a contribution of orders 1 and 2 of an expression of the thickness distribution using a least-squares-approximation with Zernike-Polynomials, and wherein the orders 1 and 2 are expressed by an indexing scheme of James C. Wyant.

10 . The glass wafer according to claim 1 , wherein the at least one parameter is selected from the group comprising:

a global wedge;

at least one of a global dome and a global bowl;

a topology of the first main surface;

a topology of the second main surface;

the maximal thickness of the glass wafer at least within the effective domain;

a minimal thickness of the glass wafer at least within the effective domain;

a thickness variation of the glass wafer at least within the effective domain;

a roughness of the first main surface; and

a roughness of the second main surface.

11 . The glass wafer according to claim 1 , wherein the ε max —which is a specific angle ε max —is 300 arcsec or less.

12 . The glass wafer according to claim 1 , wherein the local quality index LQI of the glass wafer is equal to or larger than 0.001 arcsec/mm.

13 . The glass wafer according to claim 1 , wherein the glass wafer forms, at least within the effective domain, an optical light guide.

14 . The glass wafer according to claim 1 , wherein the glass wafer is configured such that a plurality of light beams which are parallel or quasi-parallel relative to one another and which are coupled into any of the plurality of sub-domains at a feeding point of a respective one of the plurality of sub-domains under an angle of incidence propagates within the respective one of the plurality of sub-domains along a propagation path by experiencing a plurality of total inner reflections at the first main surface and the second main surface until the light beams are released out of the respective one of the plurality of sub-domains at an end point of the glass wafer under an angle of release,

wherein a difference between a plurality of the angle of release for at least two of the plurality of light beams is at least one of (a) equal to or smaller than 120 arcsec, and (b) equal to or larger than 0.001 arcsec.

15 . The glass wafer according to claim 14 , wherein at least one of:

(i) the plurality of light beams have a wavelength of between 587 nm and 588 nm;

(ii) the plurality of light beams are coupled into the respective one of the plurality of sub-domains at the feeding point by way of at least one first coupling structure of the glass wafer; and

(iii) the plurality of light beams are coupled out of the respective one of the plurality of sub-domains at the end point by way of at least one second coupling structure.

16 . The glass wafer according to claim 1 , wherein the material of the glass wafer is a glass material which comprises the following components in weight percent (wt.-%):

SiO 2

0-30

P 2 O 5

0-25

B 2 O 3

0-20

Na 2 O

0-15

K 2 O

0-10

CaO

0-5 

BaO

0-25

ZnO

0-15

La 2 O 3

0-50

Gd 2 O 3

0-10

Y 2 O 3

0-5 

ZrO 2

0-10

TiO 2

0-30

Nb 2 O 5

 0-50.