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Material Data

Fused Silica / Quartz

Both fused quartz and fused silica are at least 99.7% silicon dioxide. Fused quartz is manufactured from the melting and refusing of crushed natural crystalline quartz. Fused silica is a synthetic material fused from various chemicals in a very controlled environment.  Fused quartz and fused silica have nearly identical properties except that fused silica has much better deep UV transmission than fused quartz. The deeper UV transmission is the result of the elimination of most impurities in the synthesizing process.


Standard Materials

Esco does not manufacture optical materials. We select the most favorable materials from the marketplace and utilize them for our optics.

You can be confident that we have chosen the best performing most cost-effective materials for our components. In addition to the standard grades offered in the handbook, our technical sales department will be happy to suggest and offer intermediate grades of materials that best meet the requirements of your unique application.


Optical Characteristics

Bubbles and Inclusions are the most common visible defects that are associated with optical materials. Bubbles are trapped air spaces. Inclusions can be trapped particles of refractory. Occurrences of either is limited to larger and thicker optics. Esco typically screens out most internal defects unless they are absolutely unavoidable.

Bubbles & Inclusions

up to 1.0" dia.

from 1.0" to 2.0" dia.

from 2.0" to 3.0" dia.

ESCO Material

Max. Dia.

Max. Qty.

Max. Dia.

Max. Qty.

Max. Dia.

Max. Qty.

(inches)

per pc.

(inches)

per pc.

(inches)

per pc.

S1-UVA

0.006

0

0.008

1

0.010

1

S1-UVB

0.008

1

0.015

1

0.015

1

A1

0.010

1

0.015

1

0.020

2

G1

0.030

3

0.040

3

0.060

3

I2-IR

0.010

3

0.015

3

0.020

3

BK-7

0.006

0

0.006

0

0.010

1

* These specifications are worst case conditions.
* Materials can be selected and guaranteed to customer’s requirements.
* Bubbles less than the maximum diameter count as a fraction of the allowed limit. * Bubbles less than 0.004" are regarded as undetectable.


Homogenity refers to the variation in the index of refraction across the entire aperture of the optic. Unless you have a critical imaging or high powered laser application this is generally not an issue with our materials.

Striae refers to localized visible variations in the index of refraction shaped like thin threads. Grade A means none visible. Grade B implies almost visible. Grade C means visible to the naked eye. These defects are selected out of Esco's optics unless they are unavoidable.


Fluorescence in optics is the emission of light caused by an exposure to UV light. Fused quartz will have a strong blue fluorescence. Standard fused silica will not fluoresce unless the source of UV light is intense such as that from an excimer laser beam. UV laser applications require the use of excimer grade fused silica in order to minimize this problem. 


For more in-depth material data, please view our catalog.