Optical bandpass filters are found in a wide variety based on their constructions, and each type comes with its unique advantages.

In this blog, you will learn the fundamentals of bandpass filters such as:

  • What is an optical bandpass filter?
  • What is an optical bandpass filter used for?
  • How do I find the best-suited optical bandpass filter for an application?

So, without any further ado, let’s find the answers to these questions.

What is an optical bandpass filter?

An optical bandpass filter is an optical component that spectrally selects and transmits certain wavelengths of light while blocking others. It can be fully customized based on your unique needs and particular application.

In other words, an optical bandpass filter allows the transmission of a well-defined band of energy in the electromagnetic spectrum. Hence, they are named so.

Filters that are designed to reject the light of certain wavelengths while allowing others are called optical band-reject filters.

The width of an optical bandpass filter is expressed in terms of the wavelength range it allows to pass through.

For instance, a 1064nm bandpass filter is capable of only transmitting the small bandwidth spectrum as 1064 +/-10nm or 1064 +/-15nm while blocking or reflecting light rays of all other wavelengths.

What is an optical bandpass filter used for?

Optical bandpass filters are used in a wide array of optical applications, such as:

  • Environmental testing
  • Flame photometry
  • UV sterilization
  • Spectral radiometry
  • Medical diagnostics
  • Machine vision
  • Biotech instrumentation and more

A 1064nm bandpass filter is specifically designed for a 1064nm LED or laser light source and can be used in medical treatment, biomedical instrumentation, laser measuring equipment, and more.

How do I find the best suitable optical bandpass filter for my application?

The process of finding bandpass filters that work well for your application starts with understanding the different types of bandpass filters available in the market. Once you know which type of bandpass filter you need, you can choose a filter based on certain parameters.

Types of Optical Bandpass Filters

Optical bandpass filters are available in different types based on their construction.

  • Standard Bandpass – They are low cost and suitable for most applications.
  • Semi-Custom Bandpass – They are highly customizable and designed for specific applications.
  • High-Transmitting Bandpass – They are mostly used with PMTs and photodiodes and offer higher transmission compared to fully-blocked counterparts.
  • Hard-coated Narrowband – They feature very high transmission and are suitable for high-temperature applications.
  • Hard-coated Broadband – They are designed to cover the standard Raman spectroscopy lines and feature high transmission.

After figuring out which type of bandpass filter you need, you can find out the most suitable optical bandpass filter for your application by comparing it based on the following parameters:

  • Wavelength range
  • Bandwidth
  • Blocking
  • Size

The selection of the right bandpass filter will only help you achieve the best results. So, research well before you purchase optical bandpass filters.