How Lens Coatings Enhance a Red Dot Sight’s Performance

Chris G.

Lens coatings can make a significant difference in your red dot sight’s performance. Primarily, the coat reflects red light and makes the characteristic red reticle of the optic. They also increase light transmission, leading to clearer images. Furthermore, they improve color accuracy, reduce glare, and protect the glass from dirt and damage. 

Let’s discuss more about the details of these coatings, and how they make your sight actually work.

How Red Dot Sights Work

The basic principle that governs a red dot sight is light reflection. An energy-efficient solid-state light-emitting diode (LED) projects a beam of light—usually red—onto a tilted spherical mirror, often called a lens.

 The mirror is coated with a partially silvered dielectric dichroic coating which reflects just the red spectrum while allowing most other light waves to pass through it. As such, the beam forms into a red dot, called a reticle, that serves as an aim point.

Typically, the LED used is deep red 670 nanometre wavelength. In this wavelength, the red light is very bright and has high contrast against a green scene. An aperture at the front of the sight controls the size of the dot. 

The precise positioning of the LED and the mirror’s angle ensures that the dot is directly on your target, irrespective of the position of your eye; this is often referred to as “parallax-free.”

This system is highly dependent on the clarity and accuracy of the reflected light. Any distortion, dispersion, or loss of light can have a drastic impact on the efficacy of the sight.

The lens of the sight plays a very important role in this light interaction as it is the medium through which all the light travels. The more efficiently the lens can transmit light without distorting or losing it, the better the sight will perform. This is where lens coatings come in. 

The Role of Lens Coatings in Red Dot Sights

a man aiming a rifle with a red dot

Lens coatings enhance the performance and durability of red dot sights. These coatings are applied to the lenses of the sight and serve various purposes to improve optical clarity, reduce reflections, and protect the optics. 

  1. Anti-Reflection Coatings: Red dot sights are designed to provide a clear and unobstructed view of the reticle and the target. Anti-reflection coatings help minimize glare and reflections on the lens surfaces. These coatings reduce the amount of light that is reflected away, allowing more light to pass through the lenses and reach the user’s eye. This results in improved contrast, clarity, and overall optical performance.
  2. Anti-Scratch Coatings: The exterior surfaces of red dot sight lenses are prone to scratches from environmental factors, handling, or even cleaning. Anti-scratch coatings are applied to increase the hardness of the lens surface, making it more resistant to scratches and abrasions. 
  3. Anti-Glare Coatings: Red dot sights are often used in varying lighting conditions. Anti-glare coatings glare from direct sunlight or other intense light sources on the lens. 
  4. Hydrophobic and Oleophobic Coatings: Hydrophobic coatings repel water, and oleophobic coatings repel oils, fingerprints, smudges, grease, and water droplets. Cleaning the lens becomes easier.
  5. Dust and Debris Resistance: Lens coatings can also provide resistance against dust, dirt, and debris. Coatings that repel particles help keep the lenses clean and maintain optical performance.
  6. Color Correction Coatings: Red dot sights may include coatings that correct color aberrations or distortions, ensuring that the transmitted light accurately represents the colors of the target. This contributes to a more natural and true-to-life sight picture.

How to Clean a Red Dot Sight’s Lens

a man cleaning a red dot

Now that you understand how lens coatings are important in optimizing the performance of your red dot sight, it’s equally important to realize that regular maintenance and cleaning of the lens contribute to its longevity and optimal performance. 

You Will Need

  1. Microfiber or lens cleaning cloth
  2. Lens cleaning solution or isopropyl alcohol (high purity)
  3. Cotton swabs or lens cleaning wipes (optional)
  4. Compressed air (optional)

Steps

  1. Unload and Clear the Firearm: Before cleaning the red dot sight, ensure that the firearm is unloaded and there is no ammunition in the chamber. Safety should always be the top priority. If your red dot sight is detachable or has a quick-release mount, you may want to remove it from the firearm for easier access to the lens. 
  2. Blow Away Loose Debris: Use jets of compressed air to blow away any loose dirt or debris from the lens. This step helps prevent scratching the lens during the cleaning process.
  3. Dust Off the Lens: Gently brush off any remaining dust or particles from the lens using a lens cleaning brush or a clean, dry, and soft brush. A soft camel’s hair brush is perfect for this.
  4. Apply Lens Cleaning Solution: Apply a small amount of lens cleaning solution or high-purity isopropyl alcohol to a microfiber or lens cleaning cloth. Ensure that the cleaning solution is suitable for use on coated optics.
  5. Wipe the Lens: Gently wipe the lens in a circular motion, starting from the center and moving outward. Avoid using excessive pressure to prevent scratching. Repeat this process until the lens is clean. If there are stubborn spots, you can use a cotton swab or lens cleaning wipe for more precision.
  6. Remove Residue: If there is any residue or streaking, use a clean part of the cloth or a new cloth to continue wiping until the lens is free of streaks and marks.
  7. Inspect for Smudges and Fingerprints:
    • Inspect the lens for any remaining smudges or fingerprints. If necessary, repeat the cleaning process to ensure the lens is completely clean.
  8. Reassemble and Remount (If Removed): If you removed the red dot sight, reassemble and remount it on the firearm following the manufacturer’s instructions. Ensure proper alignment.
  9. Check the Reticle: After cleaning, check the red dot sight’s reticle for clarity and brightness. Ensure that there are no distortions or abnormalities.
  10. Store Properly: Store the red dot sight in a protective case or pouch when not in use to prevent dust and debris from accumulating on the lens.

Tips

  • Avoid using abrasive materials, paper towels, or clothing that may scratch the lens.
  • Use only lens cleaning solutions specifically designed for coated optics.
  • If isopropyl alcohol is used, ensure it is of high purity to avoid leaving residues.
  • Clean the lens only when necessary to minimize the risk of accidental damage.

Conclusion

Lens coatings play a pivotal role in red dot sights. Not only do they reflect and form the reticle, but they also aid in the optimization of light transmission and color accuracy, resulting in a sight picture that is both vivid and sharp. With appropriate maintenance, these coatings can considerably upturn your sight’s function.

About the author

The name's Chris. Just a regular dude who loves firearms. I've been shooting since I was a kid. My old man taught me the ropes.

I'll never forget the first time I missed an easy shot on a buck, thanks to a bum scope. The image was fuzzier than my dog's butt. After that, I got obsessed with understanding scopes. What makes the good ones tick and the bad ones trash. After a few years and a few thousand bucks, I learned what separates the winners from the losers. Once I had a good stockpile of knowledge, I launched this site.

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