Substrates Used for Optical Imaging

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Sapphire Coated Silicon Wafers for Optical Imaging

An associate professor requested a quote for the following.

Do you have silicon wafer with 72nm Al2O3 layer?  This is for optical imaging of multilayer graphene sheets.

We only need a single, small wafer.

Reference #116405 for specs and pricing.

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Optical Imaging Defect Distribution

A university professor requested a quote for the following.

I am looking forward a thin GaN layer grown on a thin sapphire substrate.

We are aiming at optical imaging of  defect distribution using scanning near-field optical microscope. The thickness of the GaN layer is ~1-2 micrometer. Thinner sapphire substrate  ~100-300micrometer is better. 

UniveristyWafer, Inc. Quoted:

Thin GaN layer grown on a thin sapphire substrate
The thickness of the GaN layer is ~1-2 micrometer

Thinner sapphire substrate  ~330+/-25micrometer

Reference #221642  for specs and pricing.

SOI Wafers for Optical Imaging

A Postdoctoral Research Fellow requested a quote for the following.

I’d like quotations for Silicon-on-Insulator Wafers with the following important specs:

1.      600 nm thick silicon on Fused Quartz Substrates

2.      3000 nm thick Silicon on Sapphire Substrates

3.      Double Sided Polished

As the application will be for optical imaging, I am not concerned about the doping level etc.

Reference #228978 for specs and pricing.

 

What Substrates Are Commonly Used For Optical Imaging?

Substrates commonly used for optical imaging must possess properties such as high optical transparency, low autofluorescence, minimal birefringence, and excellent flatness. Here are the most commonly used substrates:

✅ 1. Glass (Borosilicate, Fused Silica, Quartz)

  • Applications: Microscopy slides, coverslips, lenses, optical windows.

  • Properties:

    • High transparency in visible and near-infrared regions

    • Low thermal expansion (especially fused silica)

    • Chemically stable

  • Variants:

    • Borosilicate Glass (e.g., BK7): Cost-effective, commonly used for lenses.

    • Fused Quartz/Silica: High UV transparency; ideal for fluorescence imaging.

✅ 2. Silicon (Si)

  • Applications: Infrared (IR) imaging systems, sensor platforms.

  • Properties:

    • Opaque in the visible spectrum but transparent in the IR (1.2 – 7 µm)

    • High thermal conductivity, suitable for IR focal plane arrays

  • Variants:

    • Double-side polished (DSP) silicon wafers for sensor integration.

✅ 3. Sapphire (Al₂O₃)

  • Applications: Harsh environment imaging systems, X-ray optics, endoscopy.

  • Properties:

    • Transparent from UV (~200 nm) to mid-IR (~5 µm)

    • High hardness and chemical resistance

    • Low autofluorescence, ideal for fluorescence microscopy

✅ 4. Calcium Fluoride (CaF₂) and Magnesium Fluoride (MgF₂)

  • Applications: UV and deep-UV imaging optics, spectroscopy.

  • Properties:

    • High transmittance from UV to IR

    • Low refractive index—reduces need for anti-reflective coatings

✅ 5. Gallium Arsenide (GaAs) & Indium Phosphide (InP)

  • Applications: High-speed optical sensors, near-IR photodetectors.

  • Properties:

    • Direct bandgap semiconductors

    • Transparent to specific NIR wavelengths

    • Often used in integrated optoelectronic systems

✅ 6. Polymer Films (e.g., PDMS, PMMA)

  • Applications: Flexible imaging sensors, lab-on-chip devices.

  • Properties:

    • High flexibility

    • Transparent in visible light

    • Useful in microfluidics and bio-imaging

✅ 7. Glass-Ceramics (e.g., Zerodur, ULE)

  • Applications: Precision optical imaging systems.

  • Properties:

    • Ultra-low thermal expansion

    • Excellent dimensional stability

    • Used in astronomical imaging and lithography

Summary Table

Substrate Transparency Range Use Case
Glass/BK7 Visible, NIR Lenses, coverslips
Fused Silica UV, Visible, NIR Fluorescence, laser optics
Silicon NIR, IR (opaque to visible) IR detectors, MEMS
Sapphire UV to IR (~5 µm) Rugged optics, microscopy
CaF₂ / MgF₂ Deep UV to IR UV imaging, spectroscopy
GaAs / InP NIR Optoelectronics, sensors
Polymers Visible Flexible optics, bioimaging
Glass-Ceramics Visible, NIR Precision systems, astronomy