Precision Ground Flat Surface Sapphire Glass Window Lens for Optical Assemblies

Product Description

Parameter Category	Parameter Name	Value / Description / Typical Value	Test Conditions / Notes
Basic Information	Product Name	Sapphire Glass Optical Window
	Material Composition	Single Crystal α-Aluminium Oxide (
	Crystal Structure	Hexagonal Crystal System	Anisotropic Crystal
	Growth Method	Kyropoulos Method, Heat Exchanger Method (HEM), Edge-defined Film-fed Growth (EFG)
	Product Form	Flat, Spherical, Aspheric (Customizable)	Can be customized to requirements
Physical Properties	Density	3.97 - 3.99 g/cm³
	Mohs Hardness	9	Second only to diamond (10)
	Knoop Hardness	~2000 kg/mm²	Load 100g
	Young's Modulus	345 GPa
	Shear Modulus	145 GPa
	Poisson's Ratio	0.25 - 0.27
	Compressive Strength	>2.0 GPa
	Flexural Strength	> 690 MPa	Highly dependent on surface finish quality
Thermal Properties	Melting Point	2040 °C
	Maximum Operating Temperature	1900 °C (Vacuum/Inert Gas) / ~1000°C (Air)	High temps in air may cause surface devitrification
	Coefficient of Thermal Expansion (CTE)		@ 25°C
	Thermal Conductivity	25 - 35 W/(m·K)	@ 20°C, ~30x higher than ordinary glass
	Specific Heat Capacity	750 J/(kg·K)	@ 25°C
Optical Properties	Crystal Type	Uniaxial Negative Crystal
	Refractive Index (@587.6 nm)	no = 1.768 / ne = 1.760
	Abbe Number	72.2 (based on no)	Low dispersion
	Transmission Range	0.15 μm - 5.5 μm	Deep UV to Mid-IR
	Internal Transmittance	>85% @ 0.3μm (1mm thick) / >80% @ 4μm (1mm thick)	Depends on thickness and coating
	Refractive Index Homogeneity
	Birefringence	0.008	Crystal orientation must be considered
Surface Specifications	Diameter/Size Tolerance	±0.02 mm or customized
	Thickness Tolerance	±0.01 mm or customized
	Parallelism	< 3 arcsec (High Precision) / < 1 arcmin (Standard)
	Flatness	λ/10 @ 632.8nm / λ/4 (Standard)	MIL-O-13830
	Surface Finish (Quality)	10-5 Scratch-Dig (Standard) / Up to 20-10 (High Grade)	MIL-PRF-13830B
	Clear Aperture	> 90%
	Bevel	< 0.1mm x 45° (Protective bevel)
Chemical & Electrical Properties	Chemical Stability	Excellent. Insoluble in water, resistant to strong acids (e.g., HCl, HNO) and strong bases (slight corrosion at high temps). Not resistant to  (HF) and hot Phosphoric Acid.
	Water Resistance	Class 1	ISO 719
	Dielectric Constant (@1 MHz)
	Volume Resistivity		@ 25°C
	Dielectric Strength	480 kV/cm
Coating Options	Anti-Reflection (AR) Coating	Reduces reflection losses, increases transmission in specific bands (e.g., NIR, VIS, specific laser wavelength)	Single side R<0.25% @ specified wavelength
	High Reflection (HR) Coating	Achieves high reflectivity at specific wavelengths (e.g., for laser cavities)	R>99.5% @ specified wavelength
	Oleophobic/ Hydrophobic Coating	Anti-fingerprint, easy to clean, surface protection	Water Contact Angle > 110°
	Conductive Coating (e.g., ITO)	Provides transparent conductivity or electromagnetic shielding	Sheet resistance customizable
	Protective Coating	Provides extra protection against specific chemical environments
Application Fields		High-End Consumer Electronics: Smartphone camera covers, smartwatch crystals, fingerprint sensor covers. Industrial & Research: High-power laser windows, vacuum viewports, high-pressure/high-temperature viewports, spectrometer components. Aerospace & Defense: Missile domes, EO/IR pod windows, periscopes, armored vehicle viewports. Medical Devices: Endoscope protection lenses, surgical device windows, biosensors. Semiconductor Industry: Viewports for wafer processing equipment.

1. Q: "Sapphire glass? Is it made from real sapphire? Does that make it very expensive?"
A: "That's an excellent question. Sapphire glass is not made from natural gemstone sapphires. It is a synthetic sapphire crystal. It's created by crystallizing aluminum oxide at high temperatures, resulting in a manmade material with identical physical properties to natural sapphire. It's called 'sapphire glass' due to its exceptional hardness and clarity. Regarding cost, the complex manufacturing process does make it more expensive than standard or mineral glass. However, it represents a valuable investment due to its unparalleled scratch resistance and durability, ultimately saving cost and hassle from frequent replacements in the long run."

 

2. Q: "What is the primary advantage of sapphire glass?"
 

A: "Its core advantage is an exceptional Mohs hardness rating of 9, second only to diamond (10). This means it's highly resistant to scratches from everyday materials like keys, knives, or sand. Your watch crystal or lens cover will maintain a pristine, likenew clarity. Additionally, it offers excellent optical transmittance and strong antireflective properties (especially with coating), ensuring perfect readability or visibility in any lighting condition."

 

 

3. Q: "If it's so hard, does that mean it's shatterproof and impactresistant?"
 

A: "You've touched on a crucial distinction. It's important to clarify: High Hardness ≠ High Impact Resistance. Due to its extreme hardness, sapphire glass can be more brittle. When subjected to sharp, concentrated point impacts, it may be more susceptible to cracking, shattering, or chipping compared to more ductile materials like mineral glass or plastic. Its specialty is scratch prevention, not drop protection. Many highend manufacturers improve impact resistance through structural design (like domed shapes) and increased thickness, but avoiding severe impacts is still recommended."