Custom Sapphire Square Plate (Double-Side Polished) 

Custom sapphire square plates with double-side optical polishing are high-precision components manufactured from premium single-crystal aluminum oxide (Al₂O₃). With exceptional mechanical strength, excellent optical transmission, outstanding thermal stability, and superior chemical resistance, sapphire is one of the most reliable materials used in advanced optical and industrial applications. Double-side polishing ensures that both surfaces of the plate reach mirror-grade roughness and flatness, making the part suitable for applications requiring precise light transmission, low scattering, and high geometrical accuracy.

Compared with single-side polished plates, double-side polished sapphire square plates offer higher symmetry, better parallelism, improved flatness, and superior optical uniformity. They are widely used in laser systems, optical windows, scientific instruments, semiconductor equipment, spectroscopy devices, and harsh-environment observation windows.

1. Material Characteristics

Sapphire is a single-crystal form of corundum and is among the hardest optical materials available, ranking 9 on the Mohs scale. Its properties make it ideal for long-term stability in demanding environments.

Key material advantages include:

• Ultra-wide spectral transmission:
Sapphire is transparent from 150 nm (deep UV) to over 5.5 μm (IR), allowing multi-spectral applications.

• Outstanding mechanical strength:
High compressive strength, bending strength, and abrasion resistance ensure durability under heavy mechanical load or continuous wear.

• Superior chemical stability:
Resistant to acids, alkalis, and most chemical solvents, making it suitable for corrosive and high-pressure environments.

• High thermal stability:
Sapphire withstands temperatures up to 1600°C in inert atmospheres and retains structural integrity under rapid thermal changes.

2. Product Features (Double-Side Polished)

1) High-precision double-side optical polish

Both surfaces are polished to optical-grade quality, with surface roughness as low as Ra < 1 nm. This reduces scattering, enhances optical clarity, and supports high-precision laser or imaging systems.

2) Excellent flatness and parallelism

Double-side polishing supports symmetric material removal, enabling high flatness grades such as λ/4, λ/8, λ/10, or even λ/20 upon request. Parallelism can be controlled to within ≤0.005 mm for applications involving interference, laser cavities, or high-accuracy measurement.

3) High optical uniformity

The uniformity of thickness and surface quality ensures reliable optical performance with minimal wavefront distortion—crucial in precision metrology and scientific research.

4) Strong environmental durability

Sapphire’s hardness, thermal stability, and chemical resistance make the plates suitable for long-term exposure to abrasive, high-temperature, or corrosive conditions.

5) Fully customizable design

Custom shapes, dimensions, chamfering, thickness tolerances, orientation (C-plane, A-plane, R-plane), and coating options (AR, IR, AF) are available for diverse applications.

3. Standard Specifications (Fully Customizable)

4. Application Fields

1) High-power laser systems

Double-polished sapphire plates provide excellent transmission and low scatter for laser windows, beam delivery systems, and high-energy optical components.

2) Optical measurement & interferometry

Thanks to extremely high flatness and parallelism, they are ideal for interferometers, Fabry–Pérot cavities, etalons, wavefront measurement equipment, and precision optical flats.

3) Scientific and laboratory instruments

Used as viewing windows, sample substrates, inspection optics, and protective covers in spectroscopy, imaging, and analytical equipment.

4) Semiconductor and industrial equipment

Applicable in high-temperature furnaces, plasma chambers, wafer inspection tools, and precision sensors due to their resistance to heat and chemicals.

5) Harsh-environment and protective windows

Sapphire’s unmatched strength makes it suitable for aerospace cameras, underwater instruments, oil-field inspection devices, and high-pressure observation windows.

6) High-end consumer and miniature optics

Used for micro-optics, biometric sensors, small-aperture windows, and customized miniature protective plates.

5. Advantages of Double-Side Polished Sapphire Plates

1. Superior optical performance for transmission, imaging, and laser applications

2. Double-sided mirror finish ensures symmetry and low wavefront error

3. High durability against physical impact, scratch, and wear

4. Excellent compatibility with coatings and bonding processes

5. Ideal for precision assemblies requiring tight geometry and optical consistency

6. FAQ

Q1: What is the difference between single-side and double-side polished sapphire?
Double-side polished sapphire has both surfaces finished to optical quality, offering higher flatness, parallelism, and optical uniformity—ideal for high-precision optical systems. Single-side polished plates are more cost-effective when only one optical surface is required.

Q2: How thin can the sapphire square plates be made?
We can manufacture plates as thin as 0.20 mm, depending on size. Ultra-thin pieces can be evaluated based on customer requirements.

Q3: Do you offer coatings?
Yes. AR (single or double side), AF (anti-fingerprint), IR coatings, and metal films are available.