Female scientist looking up from a microscope

Illumination for Stereo Microscopy

The key to effective stereo microscopy is the correct illumination. Being able to precisely contrast a surface makes hidden details visible, and enables the viewer to accurately investigate and assess the specimen. With all the information, crucial decisions can be taken with confidence and security.

The importance of good lighting

Samples in microscopy can be diverse – from the investigation of circuit boards or flower seeds, where homogeneous illumination may be vital to stitch images together, to corrosion samples where it’s often necessary to define the surface topography by shadow effects. 

To make all relevant details visible, the correct illumination is crucial as it provides the required contrast. This is achieved by offering lighting options that are as varied as the samples themselves, and selected according to sample type. They all have different characteristics that will influence the accurate investigation of your sample.

Illustration of a stereo microscope with ring light, spot light, back light, and line light

Samples under investigation can be split into two separate groups:

Our Role

Ideal parameters for effective lighting

SCHOTT provides reliable lighting solutions for stereo microscopy that make all relevant information visible and results reproducible. We offer a range of lighting options with different characteristics, which will strongly influence the accurate investigation of your specimen. For the ideal lighting, different parameters have to be taken into account, such as the angle and form of the illumination, as well as light quality factors such as color temperature, brightness, diffused or focused light, color filters, and polarization.


Advantages of SCHOTT

Sample on a white slide illuminated with a line light

Receive realistic images

A decisive factor in stereo microscopy is achieving a realistic and reproducible image, as well as accurate documentation of the sample. With SCHOTT's illumination systems, previously hidden details are made visible.

SCHOTT sales representative presents a VisiLED ring light

Expert consultancy

With a long history in microscopy, we understand all areas of this important investigative technique – not just in theory but also in action. Our knowledge of the market and its applications enables us to provide consultancy on the best solution.

Selection of SCHOTT KL Light Guides and Light Sources

Broad portfolio

Our wide range of fiber optic and LED solutions covers all common stereo microscopy applications. This gives you a one-stop-shop with the option to choose the optimal solution for your applications.

Illumination Types

Illumination types and their typical application areas

Bright Field Ring Light

Bright Field Ring Light

Ring Lights are attached onto the objective. If the ring light is fully illuminated (Full Circle Mode), the sample is illuminated homogeneously and causing only minor shadows. Many of our LED ring lights have segment modes, which allow specific sections of the ring light to be illuminated and rotated around the sample. This enables surface topography to be highlighted and can avoid reflections on cylindrical samples.


  • Full circle mode
    Applications where homogeneous illumination is crucial. For example, image stitching.
  • Segment mode
    Suitable for flat surfaces such as leather or shiny samples like a light bulb, where reflections need to be avoided.



Spot Lights / Goosenecks / Flexible Light Guides

Spot Lights / Goosenecks / Flexible Light Guides

Spot Lights, Goosenecks, and Flexible Light Guides offer the highest versatility for stereo microscopy because the direction, as well as the angle of the light can be varied. However, the illumination is not reproducible and not as homogeneous as a ring light. They can provide strong shadow effects on flat specimens to highlight uneven surfaces.


LED Spot Lights and fiber optic Goosenecks are flex-and-stay light guides, which will remain in place after positioning. In contrast, Flexible Light Guides do not stay in place and need to be held. Goosenecks and Flexible Light Guides are compatible with our KL Cold Light Sources.



  • Flat surfaces such as a coin.



Line Lights

Line Lights

Line Lights are used to make fine surface structures on flat samples more visible. The Line Light illuminates the sample from the side at a very flat angle. The contrast on the sample is enhanced by the grazing light and the resulting shadow effects result in the surface structure being more visible. This produces a vivid 3D effect.


  • Structured surfaces of flat materials such as paper, structured laminate films, or textiles.



Back Lights

Back Lights

Back Lights are available as bright field and dark field variants, and are used to illuminate samples from below. Bright Field Back Lights are typically used for transparent stained specimens or to detect the exact 2D dimensions of opaque samples, while Dark Field Back Lights are typically used for unstained specimens.


  • All kinds of transparent specimens, such as thin plastic, insects, oocytes, nematodes, and zebra fish larvae.
  • Also suitable for optical 2D measurement of the outlines of opaque samples.




SCHOTT illumination in action

Watch this video to learn more about our products and how to choose the right lighting solution for your project.



Replacements / Spare Parts

Light sources such as the KL 1500, KL 1500 electronic, KL 1500 compact, KL 1500 LCD, and KL 2500 LCD or the ColdVision ACE® and DCR® III are not available anymore. Please take a look at the table to see which new model might work for you as replacement.

Table showing the specifications of a range of SCHOTT light sources

Light bulbs for our old light sources are still available. However, other spare parts are not available anymore for old light sources such as the KL 1500, KL 1500 electronic, KL 1500 compact, and KL 1500 LCD. 
A halogen light source can only be used with a halogen lamp. LED modules are not available.
A replacement is possible. However, halogen and LED light sources have different characteristics, so check before if your application can accept limitations in color reproduction, especially in the bluegreen and red color range. For more details, see the tab "LED vs Halogen".

Compatibility of products

The light guides of a KL 300 LED cannot be used with a KL 1600 LED, KL 1500 HAL, or KL 2500 LED. The connections are not the same. Only light guides for the KL 1600 LED, KL 1500 HAL, or KL 2500 LED can be mounted to a KL 1600 LED, KL 1500 HAL, or KL 2500 LED. For a full overview of compatibilities see our system diagrams.
The light guides of a KL 2500 LCD cannot be used with a KL 2500 LED. The KL 2500 LCD uses special light guides with active fiber bundle diameters of 12 and 15 mm. Therefore they are not compatible with a  KL 2500 LED. For a full overview of compatibilities see our system diagrams.
Our ring lights are mounted directly to the objective of the microscope. Depending on the diameter of the objective, we have ring lights with inner diameters of 40, 58, 66, 80, 81, 85, and 86 mm, as well as adapters for the 66 mm ring lights for 60, 58 and 50 mm. Take a look at our Adapter Selection Guide (Download Pdf) to see which adapter is required.
To use light guides from other manufacturers, we offer a wide range of adapters. For more details see our system diagram, ask your reseller, or contact us.

LED vs Halogen

On 1 September 2018, the EU regulation 244/2009 came into effect, which prohibits the placement of specific inefficient and non-directional household lamps on the market. However, this ErP directive 2018 explicitly excludes special lamps such as projection lamps, which relates to the used lamp in KL 1500 HAL. These can still be produced and sold.


  • Best colour reproduction, especially for red shades.
  • Same colour spectrum as sunlight in visible region.
  • Natural colour reproduction across the full spectrum.
  • Practical use case which everybody knows: Cloths, which look different in sunlight compared to a shop with neon light.
  • Use cases for microscopy include forensics, museums, medical technology, and yellow metals (brass, gold).


  • Colour temperature not consistent, between 3050K and 3400K depending on brightness setting. Optional daylight filter available.
  • Lifetime of the lamp about 50-1500 hours, depending on brightness setting.
  • Higher operational costs.

Graph comparing the intensity of the SCHOTT KL 1600 LED and KL 1500 HAL light sources


  • Long lifetime of 50,000 hours (decrease luminous lux to 70%).
  • Consistent colour temperature of 5600K (daylight) during dimming. An optional halogen filter for a more yellow color is available, similar to halogen light.
  • Low power consumption.


  • Limitations in colour reproduction, especially in the bluegreen and red color ranges.

Differences of products

The choice between those two products depends on your requirements and use case. The KL 300 LED allows multi-function illumination. It offers an easy exchange of light guides by using the same light source. Therefore, it gives full flexibility for realizing different illumination techniques with different light guides (Ring Light, Gooseneck, Flexible Light Guide, and Backlight). On the other hand, the EasyLED Spotlight Plus is a Gooseneck solution that offers brighter illumination and stronger contrast based on the independent light control of both arms.

A diffusor softens the light and reduces the reflection of LEDs on the sample. A polarisation filter eliminates reflections from the surface of the sample and pronounces anisotropic materials, but can also change the impression of the image. Furthermore, this method is very light-consuming.

The Gooseneck is a flex-and-stay light guide which will remain in place after positioning. The flexible light guide does not stay in place and needs to be held.

Where can I buy SCHOTT microscopy products?

To provide the best possible service and answer your needs, SCHOTT collaborates with a broad network of microscope manufacturers and resellers around the globe. Please feel free to contact us, including information about your location and requirements. We will be happy to guide you to relevant retailers.


Microscopy illumination for cathedral restoration

The Historical Monuments Research Laboratory (Laboratoire de Recherche des Monuments Historiques, LRMH) in France provides scientific and technical assistance for the conservation and restoration of historic monuments, whether they are buildings, large ornamental ensembles, or movable objects. Current projects involve SCHOTT’s lighting solution for stereo microscopy in the analysis of stained glass from cathedrals such as Notre-Dame de Paris.
More information