JGS1, JGS2, JGS3 Optical Quartz Glass: How to Choose?
When selecting optical quartz glass for UV, visible, or infrared applications, designers are often confused by material grades such as JGS1, JGS2, and JGS3. Although all three belong to the fused silica (quartz glass) family, their manufacturing methods, hydroxyl (OH) content, impurity levels, and spectral transmission differ significantly—making each grade suitable for different optical systems.
This article explains the differences between JGS1, JGS2, and JGS3, and provides practical guidance on how to select the right quartz material for your application.
What Is Optical Quartz (Fused Silica)?
Fused silica is the glassy, amorphous form of quartz (SiO₂). Unlike crystalline quartz, fused silica is optically isotropic, mechanically robust, and has:
- Extremely low thermal expansion
- Excellent thermal and chemical stability
- High laser damage resistance
However, fused silica can contain hydroxyl (OH) groups, which strongly affect infrared absorption, and metallic impurities, which affect UV performance. These differences define the JGS grades.
1. JGS1 – Far UV Optical Quartz Glass
JGS1 is a synthetic fused silica produced using SiCl₄ as raw material and melted by a high-purity oxyhydrogen flame.
Key Characteristics
- Very high hydroxyl (OH) content: ~2000 ppm
- Excellent deep-UV transmission
- UV transmission ≥ 90% at 185 nm
- Strong absorption peak at 2730 nm
- No grain or particle structure
- Practically free of bubbles and inclusions
- Spectral Range: 185 – 2500 nm
Typical Applications
- Deep-UV optics
- Excimer laser systems
- UV lenses, windows, prisms
- High-precision mirrors
Comparable International Grades
- Heraeus: Suprasil 1 / 2
- Saint-Gobain: Spectrosil A / B
- Corning: 7980
- Dynasil: 1100 / 4100
–>Choose JGS1 if your system operates in deep UV (<200 nm).
2. JGS2 – UV Optical Quartz Glass
JGS2 is produced by gas refining of natural crystal quartz and contains low but measurable metallic impurities.
Key Characteristics
- Moderate OH content: ~100–200 ppm
- Absorption peak at 2730 nm
- Good UV and visible transmission
- Stripe or particle structure may be present
- Bubble-free in small sizes, bubbles possible in large blanks
- Spectral Range: 220 – 2500 nm
Typical Applications
- Condenser optics
- Optical flats
- Microscope slides
- Sight glasses
- High-temperature or high-pressure windows
Comparable International Grades
- Heraeus: Homosil 1 / 2 / 3
- Dynasil: 1000 / 4000 / 5000 / 6000
–>Choose JGS2 for cost-effective UV-visible optics where deep-UV is not critical.
3. JGS3 – Infrared Optical Quartz Glass
JGS3 is designed for broadband optical performance, particularly where infrared transmission is critical.
Key Characteristics
- Very low hydroxyl (OH) content
- Absorption bands mainly in 185–250 nm
- Excellent transmission in visible and infrared
- Suitable for DUV–MIR broadband systems
- More expensive than silicon, but cheaper than CaF₂ or multispectral ZnS
- Spectral Range: UV – Visible – Infrared (extended IR performance)
Comparable International Grades
Heraeus: Suprasil 300
–> Choose JGS3 for wide-band systems spanning UV to IR or IR-dominant applications.
Quick Comparison Table
| Grade | Best Wavelength Range | OH Content | Strengths | Typical Use |
|---|---|---|---|---|
| JGS1 | 185–2500 nm | ~2000 ppm | Best deep-UV transmission | DUV optics, excimer lasers |
| JGS2 | 220–2500 nm | 100–200 ppm | Cost-effective UV-VIS | Flats, slides, windows |
| JGS3 | UV–IR | Very low | Excellent IR performance | Broadband, IR systems |
How to Select JGS1 / JGS2 / JGS3
Ask yourself:
What is the shortest operating wavelength?
<200 nm → JGS1
Is IR transmission important?
Yes → JGS3
Is cost a key driver with standard UV-VIS needs?
Yes → JGS2
Shape Optics Quartz Glass Capabilities
Shape Optics supplies optical-grade quartz glass (JGS1 / JGS2 / JGS3) for:
- UV, VIS, IR lenses and windows
- Bandpass & cutoff interference filters
- Narrowband and UV filters
- ND, notch, dichroic, and color substrates
Our engineers can help you select the correct quartz grade based on wavelength, laser power, environment, and budget.
Contact us for specific requirements or customization.