Frequently Asked Questions
Light Engines/Technical

Light Engines/Technical

Which Lumencor light engine is the right choice for my application?

The main criteria to consider when determining which Lumencor light engine is most suitable for your application are:

  1. Is the light source to be used for transmitted light microscopy, fluorescence microscopy or another application?
  2. Do you want selectable color bands or white light output?
  3. What fluorophores do you anticipate working with?
  4. Do you want onboard manual or remote computer-based controls?
  5. How do you want to direct the light output to your microscope and ultimately to the specimen (liquid light guide, optical fiber or direct coupling)? With these criteria in mind, review our product portfolio for a comprehensive comparison of all of our light engine products.  We can provide features not available in our standard portfolio products via OEM customization.
Why are Lumencor light engines considered a “greener” or sustainable illumination solution?

Here are three compelling reasons:

  1. All Lumencor light engines are not only RoHS certified, but they also contain no mercury whatsoever. The absence of any mercury makes this a much “greener” product than a mercury arc lamp or a metal halide lamp which contain very high amounts of toxic mercury.
  2. Lumencor light engines are much more energy efficient. They do not require a warmup time or cool down period, but can be turned on/off instantly, eliminating unproductive, energy consuming idle time. Furthermore, light engines can be customized to produce only the wavelength bands required  for a specific application, rather than generating a broad output spectrum from an arc lamp and then blocking large segments of it.
  3. Light engines have a long lifetime and never need bulb replacements.  Learn more about the sustainable aspects of our products.
What is a light engine?

A light engine is a high performance, illumination system composed of a hybrid of solid state technologies including LED, light pipe and  lasers. This hybrid approach allows us to overcome the shortcomings of LEDs. Our proprietary light pipe technology solves the notorious “Green Gap” problem. Where LEDs have weak output in the green-yellow region (500–600 nm), you will see that our light engines have very strong output. Light engines incorporate functions such as shuttering and wavelength switching, eliminating the need to purchase accessories to perform these functions and resulting in streamlined system integration and improved  performance. We offer customized spectral bands and adaptors to efficiently couple light into instruments. Light engines are simple to use, highly efficient, cost effective and mercury free, all in a compact design.

Why does Lumencor call the FITC channel “cyan” when FITC fluorescence is green?

Lumencor identifies light engine source channels according to the color of the light output, not the color of the fluorescence generated. Fluorescence emission always occurs at longer wavelengths than the wavelength of light used for excitation.

Fluorophore Excitation Color Emission Color
DAPI Ultraviolet or Violet Blue
CFP Blue Cyan
FITC, GFP Cyan Green
YFP Teal Yellow
TRITC, Cy3 Green Yellow—Orange
mCherry, Alexa Fluor 594 Yellow—Orange Red
Cy5 Red Deep Red—Near Infrared
What does solid state mean?

Solid state means the light generating medium is a solid material, usually a semiconductor, rather than a pressurized gas. This is in contrast to illumination sources that rely on gas discharge to produce photons.

What does Lumencor mean by “light pipe”?

Lumencor’s patented luminescent light pipe technology is a fundamental component of our proprietary light engines. Learn more.

What is the difference between SPECTRA X and SPECTRA III light engines?

The 4 main differences between the SPECTRA X and SPECTRA III light engines are:


    SPECTRA III has more output power per channel than SPECTRA X:

    Excitation Band SPECTRA III Power (mW) SPECTRA X Power (mW)
    DAPI (390/22 nm) 200 80
    FITC (475/28 nm) 215 90
    TRITC (555/28 nm) 180 165
    Cy5 (635/22 nm) 135 45

    Measurements were made at the front face of a 10X/0.5 NA objective on Nikon Ti microscope with each light engine coupled to the epillluminator using a Lumencor 3mm diameter liquid light guide and collimating adapter.


    SPECTRA X has 6 internal light sources (color channels); SPECTRA III has 8 internal light sources (color channels).


    The SPECTRA X light engine provides basic control functions of color channel selection, on/off switching and output intensity adjustment. The SPECTRA III light engine has an onboard microprocessor allowing real-time performance monitoring and feedback control, in addition to the basic control functions of the SPECTRA X. A GUI resident on the onboard microprocessor provides convenient access to extensive panel of operating status reports and preference settings.


    On SPECTRA X, the filters associated with each component light source are accessible and user-exchangeable. On the SPECTRA III, filters are not user-accessible and exchanges require a factory return for service.

What is the difference between the SOLA SM and SOLA SE light engines?

The SOLA SM light engine is Manually controlled.  White light output maybe either 100% on or off, controlled by a two-position rocker switch or an optional foot pedal accessory. The SOLA SE  light engine offers additional Electronic control  capabilities.  On/off status and intensity of the white light output is controlled via serial commands from a USB-connected computer workstation running a free Sola GUI, third-party image acquisition software or a controller pod accessory.  SOLA SE light engine output can also be selectively enabled and disabled using TTL levels applied to a BNC connector on the rear panel.

How can I distinguish externally between SOLA light engines with 365 nm ultraviolet and 395 nm violet sources?

The main distinguishing characteristic is that SOLA 365 light engines carry a purple UV label on the rear panel below the fan exhaust portal (see photo below). SOLA light engines with 395 nm violet sources do not carry this label.


Is my SOLA light engine a Generation I or Generation II model?

Generation I SOLA light engines are easily identified by their form factor (width>height; “landscape” format). Generation II SOLA light engines are taller than they are wide (“portrait” format). The images below illustrate the difference.  All SOLA SM light engines shipped after August 2013 and SOLA SE light engines shipped after February 2014 are Generation II models. Generation I is at left. Generation II is at right.


How does the Generation II and Generation III SOLA Light Engines compare?

Since we announced the new SOLA, SOLA FISH, SOLA U–nIR and SOLA v-nIR Light Engine models in November 2020, we have had many requests from customers asking how they compare with their SOLA SE and SOLA SM predecessors. In response to those requests, here is a convenient summary of the improvements made in the new generation of SOLA Light Engines:

    • Electronic control (USB and electronic shutter) on all models

    • Precisely linear (R2 – 0.9999) electronic intensity control

    • Power and light output push button controls are conveniently relocated to the front of the light engine

    • Increased output power in the cyan (FITC/GFP/AlexaFluor 488) channel (see plot below)

    • 3 mm liquid light guide now included in purchase price

    • Low (~2%) unit-to-unit output power variance

    • Backward control software compatibility with SOLA SE

There are many features of the SOLA family of Light Engines customers have come to expect over the years and we are proud to say they have also been maintained. These features include:

    • Same compact size and small footprint
    • Spectral content remains the same (see plot below)
    • Excellent short-term and long-term output stability
    • No consumables, mercury-free
Direct Inquiries


What is the output power of my Lumencor light engine?
Specific output power measurements for individual light engines are recorded on the certificate of conformance.
How linear are the output intensity settings on SOLA SE and SPECTRA X light engines?

Measured power output responses to adjustments of the electronically set intensity levels are approximately, but not exactly linear. Representative data for the SPECTRA X light engine is shown here.

What are the high-frequency on/off switching capabilities of Lumencor light engines?

For SPECTRA and SPECTRA X light engines, the maximum pulsed modulation rate is 5kHz (or 200 microsecond pulse width). The pulse rise time is 5 microseconds and the fall time is 10 microseconds.  TTL triggering is required to obtain  this level of performance (the minimum pulse width attainable via serial commands is about 10–50 milliseconds due to communication latency).  For further details, see Fast Switching Time.

Will a Lumencor light engine reduce photobleaching and phototoxicity to improve the quality of my data?

Yes. Light engines provide the ability to very rapidly ‘shutter’ the light in coordination with your digital camera so that your specimen is only exposed to light while the camera is collecting signal. Between each captured frame, when your camera is reading-out and transferring the data to your computer, the light engine will extinguish the light so that your specimen is not exposed to light anymore than necessary. Because the light engines do not require any warm-up time and do not use mechanical shutters, the light can be ‘off’ for even the short read-out period.

Is it possible to use your SPECTRA X light engine as a source for fluorescence observation?

Yes, although it is more accurate to say that the SPECTRA X light engine is a source for fluorescence excitation. Observation requires the additional use of a detector such as a camera or a human eye.

How bright is the output from a SOLA light engine?

The output from our SOLA SE and SOLA SM light engines is typically 3 W or more. We do not measure output in lumens or candela because these measurements make a photopic correction that accounts for the sensitivity of the human visual system. Generally, our customers are more concerned with achieving adequate power for a particular color band for fluorescence excitation rather than how much light your eye can see. Please note, the light output from the SOLA and other light engines is very bright and caution should be used to protect your eyes.



Why can I still detect light output when the source intensity is set at zero?

A setting of zero percent intensity does not necessarily mean zero light output.

The only way to ensure there is no light output is to set the channel ON/OFF control to OFF.  Note that channel ON/OFF and intensity are INDEPENDENT commands.  In the Generation III Light Engine (SPECTRA III, AURA III, CELESTA, ZIVA) control GUI, ON/OFF status is set by a radio button and intensity is set by an adjacent slider control.

When a channel is ON with intensity set to zero, a small amount of current is delivered to the associated light source (laser or LED).  This amount of current may or may not be sufficient to generate light output.  Light output at 0% intensity is NOT indicative of a defect or an error.  Whether light output occurs at 0% or not may vary in the following situations:

  • From one color channel to another in a single light engine
  • Between color channels of the same type (e.g. cyan) among light engines of the same model
  • In one color channel of a single light engine as the light engine ages

To ensure reliable and reproducible performance, Lumencor recommends not using intensity settings in the 0–5% range.  Lumencor light engines are designed for a normal working range of 5–100% intensity.

Why does my light engine fan stay on even when I think I have turned my light engine off?

After all component light sources (channels) have been turned OFF, with the electrical power to the light engine still ON, the fan will continue to run for a factory-set period (usually 5 minutes), to dissipate residual heat. If the fan does not shut off automatically at the prescribed time, it is often because a light source is still ON, even though no output is evident because the output intensity has been set to zero.  Despite outward appearances, setting the output intensity of a source to zero and turning it OFF are NOT operationally equivalent.

What are the correct locations for the bandpass filters associated with the light output channels of the SPECTRA X light engine?

The diagram below shows the locations for the SPECTRA X color channel bandpass filters.  When changing filters, it is advisable to remove and replace them one channel at a time.  In SPECTRA X models equipped with the near-infrared output (nIR) option, the nIR source and its associated filter replace the teal channel. The nIR source replacing the teal source will then respond to serial commands addressed to the teal channel.


What filters can be used with a SPECTRA, SPECTRA X or AURA light engine?

Bandpass filters are used to refine the spectral outputs of Lumencor’s SPECTRA X, SPECTRA and AURA light engines. A list of standard bandpass filters is available online.  Bandpass filters not found in the list can also be installed to meet individual customer specifications.  Filter customization may incur additional service charges.

How do you change the filters in a SPECTRA X filter paddle?

There is a simple procedure for changing a filter within the paddle.  Remove the unwanted filter from the filter paddle via the small set screw angled toward the filter at the bottom of the filter paddle.  Note the directional arrow on the side of the filter. Install the new filter in the same orientation (filters can only go in and out of one side of the paddle). Carefully tighten the locking set screw until it just contacts the filter (do NOT over-tighten, as this may cause the filter to crack).  Install the paddle back into the SPECTRA X.

SPX paddle

One of my SPECTRA X excitation filters seems to have fallen out of the filter paddle, how can I retrieve it?

In this case, the SPECTRA X light engine must be returned to Lumencor for service. Do not remove the exterior case of the light engine as this may void your warranty. Returns must be pre-authorized by issuance of a returned material authorization (RMA).

I need a replacement for the 542/27 bandpass filter in a SPECTRA X light engine purchased in 2013. The specification for the replacement filter is 542/33. Why the difference?

The difference in the numerical specifications is due to different definitions of bandwidth used by filter suppliers. There is no significant difference in the transmission spectra of the filters.  Transmission spectra for the current range of SPECTRA X bandpass filters are available for download. The replacement filter will typically have better out-of-band blocking and peak transmission characteristics than the original one, due to ongoing improvements in bandpass filter manufacturing processes.

Light Delivery

Light Delivery

How is the light output from the SPECTRA X light engine directed into the illuminator input port of a microscope?

The SPECTRA X light engine is not usually directly mounted on the microscope chassis. Instead, a liquid light guide is used to transmit the output of the light engine to a collimator. The collimator mounts directly to the light input port of the microscope. We design and manufacture our own collimators that are optimized for performance with our light engines. Our collimators are accessories that are not automatically included with SPECTRA X orders. We offer different collimators for each major microscope brand (Zeiss, Olympus, Nikon and Leica). You should specify which one you require at the time you place your order. Also, the optical filters used to refine the light source outputs are subject to customer specification from a standard range of options that we offer.

What is the lifetime of the Liquid Light Guide (LLG) when used with Lumencor's light engines?

When used with standard arc lamps (e.g. xenon, metal halide, mercury), liquid light guides undergo degradation caused by the large amounts of ultraviolet (UV) and infrared (IR) energy. Degradation is generally experienced as a decline in power and/or irregular illumination patterns that are visible in the field of view. Because the Lumencor standard light engines do not emit energy in these areas, the liquid guides should last for many years. Of course, if your Lumencor light engine has been specifically designed to provide illumination in the UV or IR for your applications, the LLG should be regularly examined for degradation and replaced when necessary.

What microscopes are compatible with the different light engine products and collimators?

Our light engines have been used on microscopes from Nikon Instruments, Carl Zeiss, Leica Microsystems and Olympus. We have designed high quality collimators that couple light from a 3 mm liquid light guide (LLG) or a 1 mm optical fiber into various microscopes from these four brands. The primary difference between an LLG and an optical fiber is the core: optical fibers contain glass cores while LLGs have liquid cores.  Please contact a Lumencor reseller, sales manager or technical support for information on a specific microscope model.

Why should I use Lumencor’s proprietary coupler/collimator?

To achieve the best possible imaging results, your illumination must be:

  • Evenly distributed across the field,
  • Optimized to fill the field of view without overfilling (in addition to causing a reduction of power, overfilling can cause internal scattering and reflection that degrade your image quality)
  • Optimized to bring all the various colors that comprise your illumination signal to the same focus and field.

Lumencor’s proprietary couplers/collimators are designed using the highest quality apo-chromatic optics to provide optimal power, flatness, color correction, and field of view.  Adjustments made at the time of installation assure that it the illumination is tuned to your microscope for maximum image and signal quality.

What are the numerical apertures of Lumencor’s light delivery guides?

See table below:

Light guide Part number NA
0.2 mm optical fiber 10-10262, 10-10261 0.48
1 mm optical fiber 10-10082, 10-10218, 10-10222, 10-10245 0.39
3 mm liquid light guide 10-10084 0.59
5 mm liquid light guide 10-10056 0.59
Control Functions

Software/Control Functions

My SPECTRA X does not respond as expected to TTL pulses, how can I address this issue?

The TTL response polarity of the SPECTRA X (ACTIVE = HIGH or LOW) is a pre-configured hardware setting. Care should be taken in selecting and specifying the correct setting when placing orders for SPECTRA X light engines. If you do not know the TTL setting of your SPECTRA X, please contact our technical support group, referencing the 4-digit serial number of your SPECTRA X. The TTL setting of a SPECTRA X is not field-serviceable and post-delivery changes require a return to our factory, accompanied by a Return Material Authorization (RMA). In some cases (for example, Nikon Elements, version 4.20.01 and above), it is possible to invert software-initiated TTL signals to match the SPECTRA X configuration.

I am controlling a SOLA SE light engine via serial commands from third-party software. The intensity adjustment controls work but the on/off commands do not. How do I get the on/off commands from the computer to work?

When controlling the SOLA SE from a computer, the manual light output switch on the front panel should be left in the OFF (O) position. In the ON (I) position, this switch will override on/off commands sent from the computer.

Why does pressing the foot pedal on my SOLA SM have no effect?

The front panel light rocker switch and the foot pedal on the SOLA SM (and SOLA SE) have the same control function. To avoid command conflicts, do not alternate the operation of these switches. If the front panel rocker switch is used to turn the light on, that same switch should be used to turn it off. If the foot pedal is used to turn the light on, the foot pedal should be used to turn the light off.

The power switch and light output switch of my SOLA light engine are both in the “ON” position, but there is no light output.

SOLA Light Engines have an electrical power interlock built into the liquid light guide receptacle on the front panel. If the light guide tip is not fully inserted in the receptacle, no electrical power is delivered to the light engine and the power green LED on the rear panel will not illuminate, even if the power switch is in the ON position.  To prevent the light guide becoming accidentally dislodged, secure it using the set screw on the right-hand side of the receptacle.

Customer Service

Customer Service

What is a certificate of conformance and where can I find it?

The certificate of conformance lists performance benchmarks for an individual light engine measured before it is shipped to the customer.    The certificate of conformance is included with the shipping documents e-mailed to the customer.  It is important to retain the certificate of conformance for reference.  In the event that the light engine is sold, the certificate of conformance should be transferred to the new owner. Certificates of conformance are also recorded in Lumencor’s database and copies can be requested by e-mail to techsupport@lumencor.com.  The request message must include the 4- or 5-digit serial number of the light engine.


Where can I purchase a Lumencor product?

Locations and contact information for our worldwide distributor network can be found here. Alternatively, you can submit a request for quotation using our online form.

Can I get a demonstration of a light engine product before I buy?

Lumencor has an extensive network of resellers around the world. You can contact a reseller in your region to arrange a demonstration or contact a Lumencor sales representative if you need help.

What is the warranty period for a light engine?

The table below shows the length of warranty provided to the customer:

Light Engine Model Standard Warranty Coverage
CELESTA 18 months
SPECTRA III 18 months
SPECTRA X 36 months
SOLA SE & SOLA SE FISH 36 months
SOLA SM 18 months
LIDA 36 months
PEKA 18 months
MIRA 18 months

When your new Lumencor light engine is delivered, please fill out and submit the online warranty registration form.  This will facilitate provision of warranty service should it be required.

Can you build a custom light engine solution for an original equipment manufacturers (OEM) opportunity?

Yes. A complete description of our OEM capabilities is available online.

What arrangements need to be made if my Lumencor light engine requires service?

Firstly, contact Lumencor Technical Support by phone at 503.213.4269 #4 or email to techsupport@lumencor.com. Please be prepared to provide the 4- or 5-digit serial number of the light engine, a description of the problems you are experiencing and information on the context in which you are using the light engine (e.g. what microscope and what control software you are using). This information will assist us in making a determination as to whether the problems can be resolved in situ by adjustments to the system configuration, or whether a fault has developed in the light engine that requires its return to our facility in Beaverton, Oregon for evaluation and, if necessary, repair.

If it is determined that the light engine should be returned to Lumencor, you must first obtain a return material authorization (RMA) number by submitting our online RMA request form. It is your responsibility to properly package and safely ship your light engine to Lumencor. Instructions for shipping and providing shipment tracking information will be provided in the email giving notification of the RMA number. Upon receipt, Lumencor’s service engineers will test and evaluate your light engine. if a fault is found, Lumencor will determine whether it is covered by warranty or not. For faults that are covered by warranty, Lumencor will choose to repair or replace the light engine.

For repairs covered by warranty, Lumencor will pay for return shipping. If it is determined that necessary repairs are not covered by warranty, a quotation will be provided for the cost of those repairs. In such cases, repairs will not begin until you have reviewed and approved the quotation and a purchase order has been received. You will be responsible for return shipping charges on repairs that are not covered by warranty. Please note that Lumencor’s warranty does not extend to products that have ben subject to misuse, accident, tampering or improper installation.

What are Lumencor’s certifications?

Lumencor has a wide range of safety certifications. Learn more.

14940 NW Greenbrier Parkway | Beaverton, OR 97006 USA | 503.213.4269 | info@lumencor.com