Optical Vs. Magnetic Encoders: Which One to Choose

Many industries depend on encoders to measure motion. Sometimes, that makes the selection process a little challenging. Of the different types, optical rotary encoders and magnetic rotary encoders remain popular options.

Before you buy just any rotary encoder, first look at what these two offers. Comparing the differences, you’ll have a much easier time selecting the correct one specifically for your application. After all, you want one that’s easy to use and provides accurate readings.

One of the differences between optical versus magnetic rotary encoders is how they work. The magnetic type has both positive and negative poles. Optical encoders use light that passes through a disc. Keep in mind that while they work in unique ways, they both achieve outstanding results.

Before you buy a rotary encoder or an optical encoder, consider two main factors: applications and environment.


Magnetic rotary encoders are ideal for projects that involve commodities. In particular, these encoders are suitable when there’s an installation of several encoders of the same kind, such as in mining operations. The reason is that vibration extends beyond 40Gs.

Optical rotary encoders are best when you need to record extremely dynamic motion. Not only are they accurate, but they also have exceptional resolution. Some examples of the applications for this type of encoder include machine tools, telescopes, robotics, surveying instrumentation, and antennas.


The environment where you plan to install a recorder is another important factor to consider.

Magnetic rotary encoders perform much better in environments with vibrations. So, anything with more than 40Gs would need this specific type. One important note is that a magnetic brake close to this type of encoder can interfere with its internal magnet. In that case, it could disrupt the generated signal. Also, unlike the optical type of encoder, the magnetic one can handle a higher level of contamination in an environment.

Optical rotary encoders work best in clean and relatively quiet environments. This has to do with the scanning the encoder performs. However, with various sealing and mounting options, it’s possible to get accurate readings in non-perfect environments.

Buy a Rotary Encoder That Offers the Biggest Advantages

Regardless if you need a magnetic or optical type of encoder, you should expect certain things from its performance. For one thing, any encoder needs to record accurate information. Also, look for an encoder offering excellent repeatability. Cost is also a deciding factor in some instances. However, if you buy a rotary encoder from a reputable source, you’ll end up with a quality and cost-effective product.

Turn to a Trusted Source of Top-of-the-line Encoders

Maintenance Diagnostic Systems, Inc. has top-of-the-line magnetic rotary encoders and optical rotary encoders. We have additional options, as well. When you’re ready to buy a rotary encoder, give us a call.