Thin films for the world of optics

Light is so ubiquitous and commonplace in our daily lives that we hardly ever give a second thought to its characteristics. Yet it is worth taking a closer look.

We are all very familiar with the fact, from our school days, that light consists of electromagnetic waves. The spectral range visible to the human eye lies between 400 nm and 700 nm. This ranges from the short-wavelength blue region to the long-wavelength end of the light spectrum, which we perceive as red light. But even outside the visible spectrum, electromagnetic light waves exist across a wide variety of wavelength ranges. Physically, these spectral ranges are broadly divided into the ultraviolet (UV) range, the visible light (VIS) range and the infrared (IR) range.

What all these regions have in common is that light from all spectral regions can be used to transmit information; indeed, light from all spectra enables the acquisition of data and information.

Our company, Optics Balzers Jena GmbH – one of five global sites of Materion Precision Optics, part of Materion Inc. – has made a name for itself in the development and production of optical filters. These optical filters are used to modulate light – across the spectral range from UV to well into the IR range – in a manner tailored to specific applications.

How are these filters produced? Using thin-film coating, a wide variety of materials are deposited onto optically transparent substrates. This process is colloquially referred to as ‘vapour deposition’. This is because, in some processes, materials are thermally vaporised and deposited onto the corresponding substrates.

The thickness of the individual layers is sometimes only a few nanometres. By way of comparison, a human hair is approximately 100 µm thick – that is, 100 to 1,000 times the thickness of the layers produced in this way.

The layer systems are structured in such a way that the propagation of incident light is influenced by its interaction with the coating materials. Based on physical laws such as diffraction, absorption and reflection, this interaction enables the targeted manipulation of the incident light. Only the part of the spectrum required for the application is transmitted in the finished product. In this way, individual regions of the entire light spectrum that are of interest for the respective application can be ‘filtered out’.

However, filtering spectral regions is not the only possible application. Light can also be manipulated in entirely different ways based on the physical principles mentioned above. Light can be split into different directions of polarisation. Whilst some waves propagate horizontally, others propagate only vertically. Each of these waveforms can carry different information. The separation and recombination of both waveforms is also made possible by optical filters. It quickly becomes clear just how complex the subject of optical filters can be and what a wide variety of applications can be realised using the coating technology of Optics Balzers Jena GmbH.

Optical filters are used to verify the security features on banknotes. Barcode scanners use optical filters to check the barcode pattern in a matter of milliseconds. Biomedical measurement systems are equipped with fluorescence filters. These enable the identification of viral and bacterial strains. This is an application that has developed very rapidly and extensively, particularly as a result of the COVID-19 pandemic.

Mapping and observing the Earth from space would be unthinkable without optical filters. We are therefore proud that our filters are used in various satellite missions. The data collected is used for weather analysis as well as for assessing, for example, air quality or soil moisture on Earth. Detecting ‘dark matter’ in the universe and satellite communications would also be impossible without our filters.

Applications can be found in all areas of daily life – whether in solutions for autonomous driving, in optical metrology, or for medical diagnostics. Optical filters are, and will increasingly be, an essential component of modern automation and imaging.

Optics Balzers Jena GmbH can now look back on a company history spanning more than 25 years. What began as a spin-off from the Fraunhofer Institute for Optics and Precision Engineering (IOF Jena) has since developed into a globally recognised company. There are now almost 100 employees at the Jena site responsible for the development and production of optical solutions. The sustained demand for optical solutions is impressively reflected in the company’s growth.

We would like to present our solutions and capabilities to you during the ‘Long Night of Science’ and warmly invite you to visit us at the ‘Jena-21’ industrial estate, right next to the ‘Jena-21’ stop on bus route 12.

https://www.materionbalzersoptics.com/de/