The Importance of Light in Photonics

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Simon Schwinger, CEO of LEJ || Lighting & Electronics Jena, joined the company in 2015. He provides in-depth know-how along the entire Photonics chain. Having started his career in Digital Imaging (digital camera modules and systems for scientific, industrial and consumer applications), he extended his professional background in optics (classical, polymer optics, hybrid systems) and now provides professional Illumination as well as Power Electronic solutions to the market. 

“At LEJ we are committed to light. In our understanding this covers the spectral range starting at 180nm (DUV) through the visible (VIS) up 4,000nm (IR). LEJ addresses various markets with its comprehensive set of capabilities in design & development as well as manufacturing & testing of opto-mechanical / opto-electronical / electro-mechanical sub-assemblies and systems in the field of Photonics.”


Market approach & (selected) applications

At LEJ our customers possess most of the application know-how. LEJ aims at providing the suitable (Photonics) tools for the customer to solve their application. However, there are target markets in which LEJ has gained thorough experiences during the development, manufacturing and service of Photonics systems and solutions. LEJ’s customers have been excited by the following three success pillars:

  1. Independency from the light source to be used: LEJ is experienced in developing and assembling (gas-discharge) Lamp-powered, LED-powered as well as Laser(diode)-powered sub-assemblies and systems, as well as combinations thereof (hybrid / multi-modal devices)
  2. Coverage of a broad spectral range from DUV (188nm) through VIS up to IR (HAL spectrum)
  3. Management of system-level complexities by offering sub-assemblies and complete systems (Power Electronics & Illumination)

This Viewpoint aims to provide a thorough insight on the sophisticated design of state-of-the-art professional illumination systems, highlighting the basic pro’s and con’s of “old-school” gas-discharge lamps compared to LEDs, additionally highlighting accompanying requirements to be successful.


Coming from the (gas-discharge) “lamp-era” LEJ still offers most competitive Mercury-based desktop light sources, “The Standard” in fluorescence microscopy. Especially in fluorescence microscopy cold light sources featuring very high luminance are required. Thus, Halogen or Xenon lamps are still commonly used as LED technology is not meeting the necessary performance.

However, of course LED-based solutions complement LEJ’s range of products. LEJ focusses on specialized, multi-channel LED-systems that for instance operate dichroic-free, offering not only a broad spectral range, but also significantly increased radiant power as well as comparably low product cost, resulting in advantageous total cost of ownership.

Analytical systems

Illumination devices in spectroscopic and photometric applications require light sources featuring a continuous, polychromatic spectrum (UV-VIS). LEDs cannot currently provide this. The lamps required for spectroscopy (including tungsten-halogen lamps) have an undoped quartz bulb that does not absorb the UV-A components of the spectrum. This makes them suitable for spectroscopy in the UV-A range.

If there are specific requirements for the UV spectrum solely, then LEJ is convinced that virtually all UV-A applications nowadays can be solved by LEDs. Looking at UV-B and UV-C not only does the performance of available LEDs tend to be insufficient, but the cost associated with it (originating from limited lifetime and current cost per piece) is also a limiting factor.

LEJ provides Power Electronics to major analytical instrument manufacturers.


In this field of application, users especially appreciate a broad wavelength spectrum and the presence of so-called "mercury lines" – main emission lines at 248.3nm and 253.65nm. In particular, mixed gas and deuterium lamps are frequently used. For the wavelength ranges mentioned, no replacement based on LEDs is in sight, which would be technically and/or commercially competitive. Areas of application within "Semiconductors" are the quality control of the produced wafers (wafer metrology), production and repair of the masks ("reticles") as well as Microlithography in principal.

LEJ offers power supplies (also named electronic ballasts), ignition devices and lamp housings to world-known equipment manufacturers. 

Independent from the specific application you want to solve, LEJ needs to be considered as the valuable partner to engineer and supply the necessary Photonics solution.

Besides the requirement to provide a suitable technical solution it is of paramount importance to have full control over the entire product. This leads to additional defining factors of overall product quality. 

Nowadays the quality of the product is not only defined by its technical capabilities. LEJ follows the approach of “hybrid value creation”, which combines, but is not limited to, the following additional factors:

  1. Thorough assembly and test competencies
  2. Capabilities to select and manage suppliers
  3. Strict compliance to certain industry standard

LEJ maintains a quality management system according to DIN EN ISO 9001:2015.

Additionally, LEJ products proudly carry the TÜV SÜD NRTL certification mark. This allows customers and enforcement authorities to quickly identify that a product has been evaluated by one of the most recognized names in product safety.

Our network of suppliers consists of companies, understanding our business, which is driven by the business case of our customers when it comes down to e.g. logistics concepts and service models tailored to the needs of customers and end-users.

All this combined ensures our customers the best possible overall product quality.

Product innovation

Our latest product introductions underline LEJ’s ambition to strengthen its presence in the market of Photonics:

AMPYR® UV-LED Evaluation Kit

The AMPYR® evaluation kits “LED30UV” have been developed for the fast and easy evaluation of LEDs up to 25 W.

Utilizing the “LED30UV” it is possible to carry out initial tests and test series with:

  • UV-A LEDs, e.g. in medical technology, light-curing and image processing
  • UV-B LEDs, e.g. in biotechnology, phototherapy and medical photometry
  • UV-C LEDs, e.g. for disinfection, water treatment, light therapy, sensors and falsification detection

All this can be done in an easy, speedy and reproducible way without the time-consuming and cost-intensive development of an LED carrier, driver boards and heatsinks. 

The driver has been designed for being operated with specific LED carrier boards. The LED driver adjusts itself automatically to the specified maximum currents and forward voltages of the LEDs concerned, so that the assembly will be intrinsically safe, when the power is supplied by the power supply unit provided and in the case of a thermal shutdown as described below.

The power will be supplied via a 48 VDC power supply unit with an output of 36 W. The LED driver and the LED carrier will be connected with each other by a 6-pole connecting cable. The driver current will be switched off automatically, when the LED carrier is overheated (>80°C). The LED current will be switched on again, when the temperature drops below 70°C; the hysteresis is firmly set at 10K.


The 2- or 4-channel digital lighting controller from LEJ for actuating high-power LED groups allows the precise setting of the LED current, the pulse length and pulse delay across a wide range separately for each channel. Also independent for each channel, the operating modes DC, Pulsed or Switched can be selected.

The controller is configured by either Ethernet via the internal web server or by USB directly from the user software or a service program. All parameters are permanently saved in the LED pulse controller and can be changed during operation, i.e., they can be adapted to the needs of the application.

Independent trigger inputs make fast synchronization with the user processes possible. The flexibility of configuration, the internal monitoring of all main operating parameters, together with the active self-protection, allow the uncomplicated and efficient use in image processing, microscopy,…

Why you should rely on LEJ

All of LEJ’s activities are led by the holistic understanding of the Photonics market with regards to the Photonics chain of value creation. At LEJ system integrators will find all the answers regarding the right light source and its professional utilization within a higher-level system. The quality of a light-based Photonics product starts with highest quality light source, consequently with LEJ.

LEJ is the provider of high-performance Illumination as well as Power Electronic solutions in the fields of Microscopy, Analytics, Semiconductor, Industry and Medical Technology.

Besides its comprehensive portfolio of brand products, LEJ offers the highest degree of flexibility and speed to bring customer-/application-specific products to the market. World-known OEMs count on LEJ as their system provider for e.g. laser and system power supplies, LED high-performance pulse controllers as well as their partner for contract assembly of complex opto-mechanical and opto-electronical sub-assemblies and systems.

This article is brought to you by: 
Simon Schwinger