Comprehensive Comparison of Quartz Windows and Other Material Windows

I. Overview of Window Materials

Windows are critical components in optical systems, protecting sensors, lasers, and ensuring efficient light transmission. Common materials include:

Quartz Glass

K9 Glass (BK7)

Sapphire

Polymers (e.g., Polycarbonate)

Infrared Crystals (e.g., ZnSe, CaF₂)

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II. Key Properties of Quartz Windows

1. Spectral Performance

Transmission Range:

JGS1: 185–2500 nm (UV to IR)

JGS3: 260–3500 nm (IR optimized)

Transmittance: >90% in UV-Vis-NIR regions.

2. Thermal & Chemical Stability

Softening Point: 1730°C

Thermal Expansion Coefficient: 0.54×10⁻⁶/°C

Chemical Resistance: Inert to acids/alkalis (except HF).

3. Mechanical Properties

Hardness: Mohs 7

Laser Damage Threshold: >10 J/cm² @1064 nm

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III. Performance Comparison

Material	Advantages	Disadvantages	Best For
Quartz Glass	- UV-IR transparency - Extreme heat resistance	- High cost - Brittle	Laser systems, semiconductor lithography
K9 Glass (BK7)	- Low cost - Easy polishing	- Poor UV/IR performance	Microscopes, consumer optics
Sapphire	- Scratch-resistant (Mohs 9) - High melting point (2030°C)	- Expensive - Opaque in IR >5μm	Military/aerospace sensors
Polycarbonate	- Lightweight - Impact-resistant	- Low heat tolerance (<120°C)	Consumer electronics
Zinc Selenide	- Excellent mid-IR transmission (0.5–20μm)	- Soft (Mohs 2.5) - Degrades in humidity	Thermal imaging, CO₂ lasers

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IV. Maintenance Guidelines

1. Cleaning

Step 1: Blow dust with clean air.

Step 2: Wipe gently with lens tissue soaked in ethanol.

Avoid: Abrasive cloths or HF-containing solutions.

2. Storage

Use anti-static bags in dry environments (RH <40%).

Separate thin windows (>0.5mm) with soft spacers.

3. Operational Tips

Temperature ramp rate: ≤5°C/min.

Use vacuum chucks for high-power laser systems.

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V. Future Trends

Ultra-Large Size: 600mm+ diameter windows for EUV lithography.

Smart Coatings: Anti-fogging/anti-static functional layers.

Cost Reduction: Domestic quartz production in China (e.g., CNBM’s JGS3 series).

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VI. Conclusion

Quartz windows excel in high-end applications demanding UV transmission and thermal stability. While alternatives like sapphire or ZnSe address niche needs, quartz remains irreplaceable in semiconductor and laser technologies. Advances in coating and manufacturing will further solidify its dominance.