To ensure optical clarity and optimal performance of the lens, it is essential to maintain the sapphire window. Whether it is used in scientific instruments or in high-temperature environments, we must ensure the cleanliness of the product. In this article, we will introduce you to the best materials and methods for cleaning sapphire windows to ensure long-lasting quality.
Know your coating: Cleaning coated vs. uncoated windows
The first step in cleaning sapphire windows is to determine whether your window has a coating. There are different treatments, which we will describe in detail below.
Uncoated sapphire windows are stronger than coated ones and can resist scratches from most substances, so use gentle solvents and soft fabrics to reduce any potential damage.
Coated windows have anti-reflective or thin-film coatings, which are intended to reduce glare and increase optical brightness. Therefore, this coating is relatively fragile and should be gently wiped with non-abrasive materials to avoid damage to the lens.
Essential Materials for Cleaning Sapphire Windows
Step 1: Use Compressed Air to Remove Dust
Before using any solvents, just like with a phone film, we have to make sure there is no dust on the screen, so we use compressed air to remove dust. This step is very important. You need to gently blow away dust and dirt. If you don’t find any stains or spots, you can proceed to step 2. If there are any, you still need to deal with them, otherwise scratches will appear during the cleaning process.
Step 2: Choose the Right Solvent
Avoid using ready-made glass cleaners, as they may leave streaks that affect performance. Choose reagent-grade solvents such as isopropyl alcohol, acetone, methanol, propanol, or distilled water. Always check compatibility, especially if your sapphire window has a specific coating.
Step 3: Use Appropriate Cleaning Materials
Paper towels, napkins, and regular cloths may be too rough. Instead, use lens tissue designed for optics to prevent lint accumulation and scratches. Use only moist lens tissue; dry lens tissue may cause damage.
Step 4: Wear gloves to protect your window
Even clean hands can leave oils and bacteria. Wear latex or nitrile gloves to protect your sapphire window and your hands from chemicals.
Step 5: Create a clean cleaning environment
Make sure your workspace is well-lit and disinfected. A tidy area will minimize the risk of accidental damage. For smaller windows, consider using a magnifying glass for better control.
Sapphire Window Cleaning Techniques
There are two methods we need to use in cleaning:
1. Drag and Drop Technique
This method is suitable for unmounted flat optics where the contaminated area needs to be identified. Place a clean lens tissue above the window, drip the solvent on it, and let the tissue lightly touch the window. Slowly drag the tissue across the surface, toward the nearest edge, making sure the optic remains stable.
2. Wipe Method
This method is best for small, mounted, or curved optics and requires the use of tweezers. Fold the clean lens tissue to match the size of the window, making sure no part touches your fingers or tweezers. Saturate the tissue with solvent (do not drip) and carefully wipe the surface, rotating the tissue as you go.
Contact Us
Do you have questions about sapphire windows (either coated or uncoated) or a specific application? MOK Optics can provide high-quality products and expert advice tailored to your needs.
Email: info@mokoptics.com​