OPTICAL HOMOGENEITY - FUSED SILICA

Optical Homogeneity refers to the degree of refractive index can (Δn) along the optical path within a given blank. The homogeneity of an optical element is of great importance since the variations in refractive index distort the wavefront of light transmitted through the optical component.

Synthetic Fused Silica - Optical Homogeneity
Table 1
Fused Silica Grade
Index homogeneity Class2
Maximum Index Variation
(@ 632.8 Nanometers)
Dynasil®
Corning HPFS®
79801
(X 10-6)
Optical Grade
UV Grade
X=

Selected Fused Silica

(Selected for lowest inclusions, bubbles, strain, and striae)
( See Table 2)

410X
110X
 
   
1
A
1.0
B
1.5
2
C
2.0
3
D
3.0
4
E
4.0
5
F
5.0
6
-
6.0
7
-
7.0
0
G
Not Specified

Standard Fused Silica

(For inclusions, bubbles, strain and striae specifications.)
(See Table 2)

400X
100X
 
   
1
A
1.0
B
1.5
2
C
2.0
3
D
3.0
4
E
4.0
5
F
5.0
6
-
6.0
7
-
7.0
0
G
Not Specified
Commercial Fused Silica
5000
 
Not Specified
6000
Not Specified

1Minimum external transmittance at 185 nanometers 18 80% for UV grades when measured through a 0.394"" (10mm) polished, uncoated sample.

2Index Homogeneity:

a. Blanks 12"" in diameter (or diagonal) and under will be analyzed over the full aperture. Larger blanks will be analyzed using multiple overlaping apertures.

b. The minimum thickness for index homogeneity verification is 0.750"" (19mm). Measurements are made through the optical face.

c. If requested at time of order acceptance, and for a nominal fee, interferograms will be supplied.

 

Synthetic Fused Silica - Inclusions and Bubbles
Table 2
Fused Silica Grade 4,5
Inclusion Class3
Maximum Blank Size
(Dynasil Material)
Inclusions and Bubbles
Dynasil®
Corning HPFS® 79803
Diameter or Diagonal X Thickness mm (inch)
Total Inclusion
Cross - Section
mm2 / 100cm3
(Upper Limit in in2 / in3)
Maximum
Diameter of Largest
Inclusion mm (inch)
Optical Grade
UV Grade3
Selected Fused Silica
410X
110X
0
152 X 51 (6 X 2)
0.03 (7.62 X 10-6)
0.10 (.004)
1
305 X 51 (12 X 2)
0.10 (2.54 X 10-5)
0.25 (.011)
Standard Fused Silica
400X
100X
2
203 x 51 (8 x 2)
0.25 (6.35 x 10-5)
0.50 (.020)
   
3
356 x 51 (14 x 2)
0.50 (1.27 x 10-4)
0.76 (.030)
4
559 x 76 (22 x 3)
1.00 (2.54 x 10-4)
1.00 (.040)
Commercial Fused Silica
5000
 
5
559 x 102 (22 x 4)
2.00 (5.08 x 10-4)
1.27 (.050)
6000
559 x 102 (22 x 4)
4.00 (1.02 x 10-3)
2.03 (.080)

3 Inclusions, bubbles and seeds smaller than 0.10mm (0.004"") in diameter are disregarded in this specification.

4 All Selected and Standard Grade material meets the striae requirements of ISO 10110-4 Class 2/5 (No Visiblie Striae) in the thickness direction.

5 All Selected and Standard Grade material meets or exceeds the stress birefringence requirements of ISO 10110-2 Class 0/5
(Optical Path difference ≤ 5 nanometers per centimeter). Other specicications available upon request.

 

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Designed by Kim Kelly