YAG Crystal
YAG (Yttrium Aluminum Garnet, Y₃Al₅O₁₂) crystal is a high-performance laser and optical material known for its high hardness, high thermal conductivity, good chemical stability, and excellent optical homogeneity. It is widely used in solid-state lasers, LED phosphor substrates, optical windows, medical laser equipment, and defense electro-optical systems.
Hemei Company possesses profound technical expertise in the precision machining of hard and brittle materials. For YAG crystals, Hemei has developed an efficient and stable polishing process that enables fully controllable processing from rough to fine polishing, ensuring the YAG crystal surface meets "laser-grade" or "optical-grade" quality standards.
Application Requirements
The polishing objectives for YAG crystals include:
Reducing surface roughness (Ra) to < 0.5 nm.
Achieving surface figure accuracy (PV value) better than λ/10 (@632.8 nm).
Ensuring a damage-free surface with no sub-surface cracks, meeting laser-induced damage threshold requirements.
Controlling thickness uniformity (TTV) within a specific micrometer range.
To achieve these goals, Hemei's process employs customized bonding systems and multi-step polishing procedures to ensure geometric accuracy and surface integrity during processing.
System Specifications
Hemei's modular polishing system supports processing YAG crystals of various sizes and shapes. Core systems include:
HSM-L/LP Series lapping Equipment: For initial material removal and thickness control.
HSM-CMP Series Chemical Mechanical Polishing (CMP) System: For achieving ultra-smooth, damage-free surfaces.
Key subsystems include:
Wafer/Crystal-specific Bonding Unit (WB)
SJ/ASJ Series Precision Polishing Fixtures
C-ASJ Drive Head High-Speed Polishing System
Processing Flow
Bonding and Mounting: The YAG crystal is temporarily bonded to a support plate using the WB unit, then mounted onto the polishing fixture.
Rough and Intermediate Polishing: Controlled lapping is performed on the HSM-L equipment to remove the processing damage layer.
Fine Polishing: The HSM-CMP system performs the final polish. Parameters like pressure, rotation speed, and slurry flow are adjusted in real-time to achieve nanometer-level surface smoothness.
Typical Results
Surface roughness Ra < 0.5 nm.
Surface figure accuracy PV ≤ λ/10.
Controllable material removal rate of 1-2.5 μm/min.
Suitable for YAG wafers up to ≤ 6 inches in diameter and shaped crystals.
Hemei Company provides a complete and reliable polishing solution for YAG crystals, capable of consistently delivering nanometer-level surface quality and high optical performance. This supports the industrial application of YAG crystals in high-end fields such as lasers and optoelectronics.
