Is your optical filter the weakest link in your device?

Unfortunately, many product developers fail to consider the key importance of the optical filter. This often means that the optical filter is the weak link in the chain of components that constitutes the complete product.

Choosing a sub-prime optical filter leads to several disadvantages – which we will dive into in this short guide to choose the optimal optical filter for your exact application. The guide has 3 main focal points:

• Protection
• Performance
• Processing

By considering these 3 factors, we hope to guide you toward the optimal optical filter and towards improving the performance and durability of your light sensing & scanning device.

Enjoy!

Shielding your device against the environment

Is your device exposed to a harsh environment?

Then you might benefit from the most straightforward use of an optical filter as a shielding protection against dangers threatening the performance and durability of your device. You might need an impact-resistant layer in front of the more expensive components.

Depending on your application, you might also need a device with resilience against cleaning agents or other chemicals.

Abrasion resistance could be another key factor to ensure better durability of your device. Overall, using the optical filter as a shield against the environment enables you (or your customers) to replace the filter when needed – instead of replacing the expensive components behind the filter.

Improving the Signal-to-Noise ratio of your device

When it comes to applications such as machine vision, the Signal-to-Noise ratio is one of the most important factors to consider. But how do you minimize the amount of unwanted interfering light? Well, there are several approaches – in the end, it all comes down to your application, the environment your device is used in, and the device’s sensor.

Are you looking for an optical filter solution for a machine vision application? Then don’t forget to check out this article that presents six challenges and solutions to pick the perfect optical filter solution for machine vision applications. Click here to read it right away.

Here, we present the three most important and common ways of improving the Signal-to-Noise ratio.

1. Minimizing surface reflections by adding an anti-reflective coating to the optical filter

It’s possible to lower the reflections from 8% down to 1%. This makes it possible to let in as much as 99% of the wanted wavelengths. This stronger signal is easier and quicker to read.

2. Eliminating unwanted wavelengths using colored optical filters

A colored optical filter only lets in the correct wavelengths, depending on your specific application. If your sensor only needs these wavelengths, the Signal-to-Noise ratio is improved drastically, and you give your sensor the best possible conditions to succeed with high speeds and a low margin of error.

Click here to see the transmission curves of our Solaris™ acrylic solutions.

3. Printed shadow masks minimize bouncing light

In devices with more than one sensor, you can minimize the amount of reflecting light that bounces between sensors by printing shadow masks on your optical filter. This simple but effective approach ensures as little interference as possible between different sensors used in the same application.

Designing and producing optical filters to fit your device

Now that we have considered how to maximize the performance and protective abilities of your optical filter, it is time to discuss the importance of precise mechanical processing and a well-thought-out design.  So, what do you have to consider?

• First, you will often need your optical filter cut to exact measurements. The tolerance for variation is often minimal.
• Second, you need to consider the thermal expansion of the different materials in your device. This adds to the complexity and should be an essential part of the design process. If you fail to consider thermal expansion – or install an imprecise optical filter with too little room for expansion – your device might crack once it enters the harsher in-use environment with fluctuating temperatures.
• Third, you must ensure a safe, secure, and tight encapsulation while leaving room for thermal expansion. This comes down to the design and an understanding of the materials. The glue joints need to leave a proper amount of space for flexibility while ensuring a tight fit. To achieve this, you must have a thorough understanding of the material properties of your optical filter.

We hope that this article has given you some insights about the importance of choosing the right optical filter for your device.

Here at PSC, we are experts when it comes to optical filters for pretty much any kind of application. Therefore, we are always open for a talk about your solution so we can show you how we can help you – no matter what kind of application you need a cover glass solution for.

Interested? Then click here to get in touch with us immediately.