Optics and sensors

Blösch's high-end coating solutions have many applications in the markets of Optics & Sensors.
Customers value in particular Blösch's:

  • Solution-oriented engineering
  • Wide portfolio of technical capabilities
  • In-house optical and metallic coating competences
  • Hermetic integration systems
  • Test and qualification services
  • Overall customer support
market icon
Job Coating Services
market icon
market icon
Customized solutions
Services Top Shape Yellow


Both Physical Vapor Deposition (PVD) and electroplating belong to Blösch's portfolio of metallization technologies.
Our PVD coating processes are optimized for depositing stacks of  metals and alloys.
Our electroplating processes enable the deposition of thick metals layers.
The combination of PVD and electroplating provides unique capability and features for many applications.

Optical coatings

Optical coatings provide the parts with the transmission and reflection spectra, as well as other functions necessary for the application.

Optical components

Blösch supplies coated components to its customers who wish to rely on Blösch's experience in substrate materials and suppliers.

Other components

Blosch reaches always out to his customers to help them with their needs for components.

Hermetic integratable optical windows

Optics and sensors systems, whether for medical applications, the food industry, harsh environments applications such as in aerospace and defense conditions, or also in order to meet the high lifetime requirements of telecom equipment, require hermetically sealed optical windows.
Blösch's portfolio of technologies and competences includes all the building blocks of hermetic integratable optical windows.

Your project

Solderable coatings

The hermetic integration of a protective window for sensors and visual systems is critical, in particular the interface between the sapphire, glass or ceramic window to the metal housing. The superior solution to achieve a stable and robust interface between those materials is an all-metal interface, that is build up on a solderable coating applied selectively on the non-metal protective window. The hermetic integration is then achived by brasing (e.g., AgSn or AuSn).

Our solderable metal coatings are durable and resist to high temperature and harsh environmental conditions. They provide the highest quality sealing for hermetic packaging for various applications, e.g., medical and industrial endoscopes, food and beverages (e.g. turbidity sensors), environmental analytics, optical switches for telecom, analytics for pharaceuticals, industrial robotics, agriculture, generators and aerospace.

Standard design

The standard design consists in depositing the solderable coating along a defined zone on the same surface as the optical coating. This design is flexible and very precise.

Key performance parameters:

  • Solderable coating solution for rectangular and round flat windows
  • Selective application on a defined zone allows seamless and easy integration of an optical window to the metal housing
  • Ideal coating solution for larger hermetic windows
  • Substrates may be either sapphire, fused silica, or most crystals, glasses and ceramics
  • Windows can be additionally coated with an optical filter

Compact design

The compact design consists in depositing the solderable coating on the surface that is perpendicular to the optical surface (side edge of the window). This design is recommended for all space-limited applications.

Key performance parameters:

  • Solderable coating solutions for the side edge of optical windows or lenses as well as for non-transparent ceramic windows
  • The side edge of very small components, down to sub-millimeter dimensions, can be coated for soldering
  • Ideal coating solution for size-critical hermetic windows such as in endoscopes and space-limited sensing devices. The full optical surface of the windows and lenses can be used for the sensing or visual application
  • Cylindrical, flat or other surface shapes can be coated
  • Substrates may be either sapphire, fused silica, or most crystals, glasses and ceramics
  • Windows or lenses can be additionally coated  with an optical filter

Structured thick metal coatings

Blösch's Physical Vapor Deposition (PVD) and electroplating technologies, along with the possibilities to pattern the surface with photolithographie techniques, are the bulding blocks for structured thick metal coatings.

Examples of applications of thick-metal structures:

  • Microfluidic circuits
  • Spiral antennas on sapphire
  • MEMS structures

Antireflective coatings

Antireflective coatings (ARC) eliminate the adverse effects of unwanted reflection and maximize the transmission in the desired wavelength ranges.
Blösch offers standard ARC solutions that present the advantages of lower costs and lead-times.
Custom ARC 's are efficiently developed on the basis of the standard ARC solutions.

Standard VIS AR coating

Blösch's standard VIS antireflective coating is optimized for the visible range of wavelengths.

Key performance parameters:

  • Reflectance on sapphire
  • R < 0.5% typically
  • Range 390-610nm (VIS)

Standard VIS-NIR AR coating

Blösch's standard VIS-NIR antireflective coating is designed for the visible and near infrared range of wavelengths.

Key performance parameters:

  • Reflectance on sapphire
  • R < 1% typically
  • Range 400-900nm (VIS-NIR)

Custom AR coating

Customized AR coatings are designed on the basis of Blösch's standard ARC solutions and its engineering experience.

Ultra-resistant AR coating

Blösch‘s ultra-resistant antireflective coating offers both a rugged protection and a broadband anti-reflection. The wavelength band can be tailored to some extend to specific applications needs.

Optical filters

Optical filters provide wavelength-selective transmission and reflection.
Blösch offers custom optical filter solutions, that block undesirable wavelengths or wavelength ranges, while allowing the low-loss transmission of desirable wavelengths or wavelength ranges.
Please contact us to discuss your needs and our solutions.

Longpass filters

Longpass filters are transparent to long wavelengths, while they block short ones. 
We offer for instance UV filters, that eliminate the UV light. These filters can be customized in wavelength.

Bandpass filters

Bandpass filters enable to selectively filter out a range of wavelengths while transmitting the surrounding wavelengths.

Additional functions

The optical coating's reflection and transmission characteristics may be complemented with additional functions. Multi-function coatings are possible. Please contact us to discuss your needs and our solutions.


Metal coatings of Aluminum or Silver, for instance, are excellent reflectors over broad wavelength ranges.
The metal mirror coatings include protection layers against oxidation.

Conductive optical coatings

As ITO is both transparent and conductive, it is effectively integrated along with anti-reflection or filter coatings to enable for instance:

  • Heating
  • Protection from electromagnetic radiation
  • Other electrical functions

Anti-fog optical coatings

Hydrophobic coatings limit the adhesion of water and other liquids to the surface. Among other beneficial features, this property prevents the formation of condensation when the environment temperature changes rapidly.  The coating is compatible with anti-reflective coating.

Black coatings

The efficiency of optics and sensor systems is much improve by the elimination of stray light. This is achieved by highly absorbing black coatings on selected zones of the optical device. Blösch has extensive experience in the deposition of black coatings based on chromium or carbon, on sapphire and glasses.

Protection windows and lenses

Optical sensors and vision systems require a transparent window for protection from the application environment.

In addition, lenses are essential components of many optical systems, both for the emission and the reception of light.

Protection and hermeticity

As hermeticity is required in most such applications, the protective windows have a metallized edge for brazing into a housing.


Optical substrates

The application commands the choice of the optical substrate material and of its characteristics.
Small sizes down to sub-millimeter dimensions for space-limited applications such as some sensing applications or medical endoscopes are possible.


Sapphire crystals are transparent in the visible and near infrared, and are extremely hard. These properties make sapphire the substrate of choice for demanding window and lens applications. The medical sector, the food industry, harsh environments such as in aerospace and defense conditions, high lifetime demanding telecom equipment, are examples of the numerous applications requiring sapphire substrates for both their optical, mechanical, and other properties.


Other substrate materials

While Blösch has a unique experience with sapphire substrates, other materials are also routinely coated for numerous applications. These include:

  • Fused silica
  • Mineral glasses
  • Crystals
  • Ceramics
  • Semi-conducting materials

Please contact us to discuss your project

Optical sub-units

Blösch supports its customers with solutions for the integration of optical components into sub-units.

Examples of sub-units

Sub-units are components of our customers' systems.
Blösch offers to complement the coating work up to its customers core competences, by releaving them from non-core specialized operations. Depending on our customers and on the application, sub-units may be:

  • Optical windows mounted on a metal or ceramic substrates;
  • Sapphire lenses integrated in a holder;
  • Lids of telecom devices;
  • Many other applications.

Blösch will either process customer supplied parts, or offers the service to acquire the parts on behalf of its customers.

Examples of applications

Turbidity sensor

In the food & beverage industry, process and quality controls include the measurement of the turbidity of liquids. The brewing of beer or the fabrication of milk products are examples.

A turbidity sensor consists in a light source emitting into the liquid, and in a light receiver detecting the reflected light from the natural particles that cause the turbidity.

Since the sensor is dipped into the liquid, a transparent protective window is brazed to the housing of the sensor for hermeticity. The edges of Blösch's protective windows are metal-coated to enable the hermetic brazing, and are treated with an anti-reflection coating to enhance the quality of the optical signals. Both coatings and the brazing for hermeticity are compatible with the requirements of the food and beverage industry.

Total Suspended Solids (TSS) monitor

The monitoring of suspended solids in water provides essential information about its quality. It has applications in industry processes, in control of waste waters, as well as environmental surveillance.

The suspended solids may be of various sizes. but the measurement of Total Suspended Solids (TSS) is overwise similar to the one of turbidity.

Because of the harsh conditions of use of the TSS monitors, the transparent protective windows require very resistant coatings in addition to their optical and metallic properties for hermetic integration.

Key Blösch technologies

Blösch offers a wide range of both standard and customized coating solutions.

Blösch's solutions


The benefits of Blösch‘s solutions for hermetic integratable optical windows are:

  • Solderable coatings and integration go hand-in-hand
  • Soldering experience gained from numerous projects in various markets with their respective application conditions
  • In-house engineering & design
  • Relationship to suppliers up the value chain
  • Sub-units are designed and qualified for specific applications
  • Blösch‘s systems enable to customize the sub-units,
  • and includes the option to procure all parts and materials

Our services

We are always listening to your needs and will consider developing new and custom-specific solutions:

  • Novel materials
  • Novel substrates
  • Novel processes

A collaborative approach

As a business partner, you are the focus of our daily work!

Our contribution to your success:

- Customized solutions for application-specific coatings
- Top-of-the-class engineering and manufacturing expertise
- Support in multiple aspects of your project, as needed, from upstream material procurement to downstream integration
- Resources available from sister companies Liss a.s. and Platit AG within the BCI Blösch Group
- Extensive research and development facilities and a wide range of analytic instruments

Your advantages:

- Create a market advantage for yourself: Your individual coating solution is tailored to your application and is therefore particularly effective
- Your own branding: Create your own coating name and create a unique selling point
- Prepare yourself for the future: The needs of the market and applications are constantly evolving - a partnership with Blösch keeps you and your application needs at the cutting edge of technology