LFA L51 - Where Thermal Analysis Meets Innovation
The LINSEIS LFA L51 is a versatile Light Flash Analyzer for high-precision measurement of thermal diffusivity, thermal conductivity and specific heat. It is ideal for analyzing solids, powders, pastes and liquids in a wide range of industrial applications such as electronic packaging, heat exchangers, thermal insulation and reactor cooling. With a broad temperature range from -100 °C to 1250 °C, the LFA L51 offers fast, non-contact and non-destructive measurements with minimal sample preparation and high accuracy.
This absolute method requires no calibration and complies with international standards such as ASTM E-1461, DIN EN 821-2 and DIN 30905. The system is equipped with user-exchangeable InSb or MCT detectors (LN2 or Peltier cooled), with optional automatic LN2 refilling. Vacuum and inert gas operation is supported via an optional gas dosing system, ensuring maximum flexibility for advanced thermal analysis.
Unique Features
Software Improvements
- New LINSEIS LiEAP software: Our completely new software plattform is now even more focused on the needs of our customers to ensure that you are always informed of the latest status and receive support whenever it is needed.
- Automatic updates and new features: Our software receives regular automatic updates that not only improve security, but also continuously provide new features.
- Lex Bus Plug & Play: Our latest hardware interface Lex Bus revolutionizes the way data communicates within our systems. Lex Bus enables seamless and efficient integration of new hardware and software tools.
- Improved furnace control: Our new and further improved furnace control offers more precise temperature control, which leads to better measurement results and higher throughput through better temperature sequencing according to your wishes and requirements.
- Preventive maintenance and problem detection: Using intelligent components and accessories, our preventive maintenance approach detects problems and wear and tear before they can cause damage and keeps your device in top shape.
New improved light guiding system
Brings more energy to the sample and pushes the boundaries. The novel light guiding system significantly extends the measuring range by maximizing the power reaching the sample and leading to up to 3x stronger signals. This is particularly evident in samples exhibiting lower thermal conductivities or greater thickness, which are more easily and accurately measured.
Linseis Lab Link
With Linseis Lab Link, we offer an integrated solution to address uncertainties in measurement results. With direct access to our application experts via the software, you can get advice on the correct measurement procedure and evaluation of results. This direct communication ensures optimal results and maximizes the efficiency of your measurements for precise analysis and research as well as a smooth process flow.
Design Improvements
The new device design is characterized by an elegant aluminum casing that is both robust and aesthetically pleasing. The LED status bar provides a user-friendly visualization of important information. A touch panel enables intuitive operation and contributes to a modern user experience that combines comfort and functionality. The new device design focuses on ergonomic operation.
PLH Upgrade
The L51 LFA instruments can be upgraded with the PLH (periodic laser heating) option. This patented 2-in-1 solution provides two measurement techniques in one instrument, maximizing the range of applications and enabling analysis of samples ranging from µm to mm thickness.
The PLH technology has been specifically developed and optimized to characterize thin film samples with unparalleled accuracy. It covers a measurement range of sample thicknesses from 10 μm to 500 μm and a thermal diffusivity range spanning from 0.01 to 2000 mm²/s.
The PLH L53 option can handle a wide variety of materials, making it suitable for:
- Heat spreader materials such as graphite foils and thin copper foils,
- Semiconductors with complex thermal properties,
- Metals requiring precise diffusivity measurements,
- Ceramics and polymers used in advanced material systems
Anisotropy and inhomogeneity analysis
With its advanced mapping capabilities, the PLH system enables the spatially resolved measurement of thermal diffusivity across a sample. This feature is particularly valuable for identifying anisotropies (directional differences in thermal behavior) and inhomogeneities (material inconsistencies). By scanning multiple regions, users gain a comprehensive understanding of the thermal properties of thin films, ensuring optimized material performance for demanding applications.
Applications and Industry Focus
Typical applications include the analysis of freestanding films and membranes, which are of increasing importance in the battery and hydrogen industries. The ability to accurately measure thermal transport properties in these materials is crucial for improving energy efficiency, thermal management, and overall system performance.
Key Features at a Glance
- Anisotropy analysis: Combines cross-plane and in-plane measurements seamlessly.
- Versatile material compatibility: Suitable for semiconductors, metals, ceramics, and polymers.
- Mapping capability: Allows precise spatial analysis of anisotropies and inhomogeneities within the sample.
- High measurement accuracy: Covers a broad range of sample thicknesses and thermal diffusivity values.
Highlights
Wide temperature range:
-125°C to 2800°C
High measuring accuracy
and repeatability
Modular design for
flexible customization
Fastest measuring times thanks
to laser/light flash technology
User-friendly software for
comprehensive data
analysis
Suitable for solids,
layers and liquids
Key Features
New Electronics
- Enhanced Amplifier Electronics: Upgraded electronics improve signal-to-noise (SNR) and 16-bit resolution, ensuring accurate and reproducible measurements for thin or conductive samples.
- Higher Data Acquisition Rate: A 2.5 MHz acquisition rate enables precise analysis of fast-conducting and thin materials, capturing detailed data in short timeframes.
- Improved communication: Either USB or Ethernet can be used to operate the Linseis equipment as stand alone or in a bigger network
Optimized Low-Temperature Furnace
The newly introduced signal-optimized low-temperature furnace ensures gradient-free, high-accuracy measurements at lower temperatures and an increased speed for higher throughput.
Gradient-Free Hot Zone
The temperature control of the furnace is optimized with a gradient-free hot zone. This design ensures that the entire sample is subjected to uniform heating, leading to enhanced measurement reproducibility which is critical for accurate thermal conductivity results.
Peltier cooled detector
Two cooling options are available for IR detectors: a liquid nitrogen-cooled version and a thermoelectric (Peltier) cooled alternative. Although the Peltier-cooled detector has a slightly lower signal-to-noise ratio, it impresses with its high practicality. It is the ideal choice, especially in environments without access to liquid nitrogen, such as in protected areas like glove boxes.
External Electronics for Controlled Environments
The LFA can be integrated with external electronics for use in glove boxes or hot cells, allowing it to be used in controlled environments where sensitive materials or hazardous conditions may be present.
Complete Sample Illumination
The LFA L51 ensures full illumination of samples up to 25.4 mm in diameter avoiding a radial temperature gradient in the sample. This results in improved reproducibility and more consistent results across a wide range of sample sizes.
Questions? We're just a call away!
+1 (609) 223 2070
+49 (0) 9287/880 0
Our service is available Monday to
Thursday from 8-16 o’clock
and Friday from 8-12 o’clock.
We are here for you!
Specifications
Temperature range: –100 °C to 1250 °C
Thermal conductivity: 0.1 to 4000 W/(m·K)
Thermal diffusivity accuracy: ±2.4 %
Discover our high-performance LFA – engineered for rapid and reliable thermal conductivity analysis:
- Flash source: Software-controlled light flash (15 J/pulse, 50–2000 µs pulse width)
- Detector options: InSb or MCT (LN₂ or Peltier cooled)
- Vacuum capability: Down to 10⁻⁵ mbar
- Flexible sample handling: Solids, powders, pastes, laminates, thin films
- High-speed data acquisition: 2.5 MHz
Method
Light Flash Analysis
The Light Flash Method (LFA) is a fast, non-contact technique for determining the thermal diffusivity, specific heat and thermal conductivity of solids, powders and pastes. A short energy pulse heats the rear face of the sample, and the resulting temperature increase on the front surface is recorded over time using a high-speed infrared detector.
The temperature rise curve reflects how quickly heat travels through the sample. From this data, the thermal diffusivity is calculated. When the specific heat and density of the material are known, the thermal conductivity can be determined as well.
LFA is a non-destructive and highly precise method, widely used in materials research, electronics, aerospace and energy applications. Its key advantages include short measurement times, minimal sample preparation and the ability to test a wide range of materials – all with high repeatability and under controlled atmospheres.
Measurement Principle
During an LFA measurement, the sample is heated to a defined temperature inside a furnace or microheater. A programmable light pulse – typically generated by a laser or xenon flashlamp – is applied to the bottom side of the sample. This causes an instantaneous heating of the rear face, resulting in a temperature rise at the top surface.
This temperature change is recorded with a sensitive IR detector as a function of time. The resulting temperature–time curve is used to calculate the thermal diffusivity, based on the half time of the temperature rise and the thickness of the sample. With additional knowledge of specific heat and density, the thermal conductivity can be derived.
This method provides accurate results with short measurement durations, supports a wide temperature range and enables measurements under vacuum or controlled gas atmospheres.
Measured Properties
Thermal diffusivity (α [mm²/s])
Specific heat capacity (Cp [J/g·K])
Thermal conductivity (λ [W/m·K]) (calculated via α · Cp · ρ)
Temperature-dependent thermal properties
Repeatability and accuracy data
Supported Methods and Capabilities
Multi-sample measurement (up to 18 samples)
Thin film analysis (with PLH module)
Isothermal and temperature-dependent measurements
Analysis of anisotropic materials
Measurement of powders, pastes, solids and laminates
Measurement under controlled atmospheres (inert, reducing, oxidizing)
Vacuum measurements (down to 10⁻⁵ mbar)
High-speed data acquisition for fast thermal events
A head start with the LFA L51 – flexible solutions for every thermal challenge
PLH L53 - Periodic Laser Heating
LFA L52 Nuclear
Questions? We're just a call away!
+1 (609) 223 2070
+49 (0) 9287/880 0
Our service is available Monday to
Thursday from 8-16 o’clock
and Friday from 8-12 o’clock.
We are here for you!
LFA L51 uncovered – how it works, where it fits, what it offers
Measurement Concept
The sample is either positioned on a sample robot, which is surrounded by a furnace (LFA L51 LT/500/1000) or within one out of five microheaters located on a moveable linear stage (LFA L51 1250). For the measurement, the furnace is held at a predetermined temperature and a programmable energy pulse irradiates the rear side of the sample, resulting in a temperature rise at the sample surface. This resulting temperature rise of the surface of the sample is measured by a very sensitive high speed infrared (IR) detector . Both, thermal diffusiviy and specific heat can be determined from the temperature vs. time data. If the density (ρ) is identified, the thermal conductivity can be calculated via:
Vision Control
Measurement principle
In a Flash system the signal quality depends on the amount of radiation of the sample which hits the surface of the infrared detector. Normally, the active surface of the detector is limited (e.g. 2×2 mm2) compared to a sample diameter of (3 mm to 25.4 mm). For this reason, an optimized arrangement of IR-detector, lens and sample is used to improve the imaged sample surface. The measurement spot on the sample should be as large as possible, but it should not exceed the sample. Any exceeding of the spot can generate measurement artefacts or additional noise on the signal. The vision control feature provides best signal quality for any sample dimension. The optimization ensures superior signal quality for big and small samples.
Vision control
The „vision control“ option ensures a perfect detection spot for different sample geometries. This allows the perfect adaption to image the sample surface ideally and sharply on the sensor active area.*
*Not available in all configurations and countries
High speed infrared furnace or micro-heater for unmatched sample throughput
The LFA 51 device can be equipped with either a high-speed infrared furnace (LFA L51 500/1000), an advanced micro-heater (LFA L51 1250) or an low temperature resistance furnace (LFA L51 LT), allowing for exceptionally fast heating and cooling rates. This rapid temperature adjustment minimizes downtime, saving valuable time and enabling a high sample throughput for increased lab productivity. With this technology, numerous samples can be analyzed in a short period, which is especially beneficial for time-sensitive applications. The infrared and micro-heating technology also ensures precise and uniform temperature control, delivering reliable and accurate measurement results.
Because time matters
Comparison of time to reach the temperature stability.
A high speed IR-micro-heater furnace reaches the set temperature much faster and delivers a superior iso-thermal temperature stability.
Cooling comparison of IR furnace, micro-heater, and MoSi resistance-heater clearly demonstrates the
advantage of short cool-down times. This allows
multiple measurements in quick succession and
improves sample throughput. The IR furnace cools from 1000°C to 30°C in 105 minutes, while the micro-heater takes only ~26.5 minutes. Even when cooling from 1250°C, it stays below 30 minutes. The MoSi-heater, used for comparison, cools from 1560°C to 19°C in approximately 147 minutes.
LFA L51 Furnaces
LFA L51 500
This model offers cost-effective thermal conductivity, diffusivity, and specific heat measurements for up to 6 samples, with a temperature range of RT to 500°C and fast IR detection for precise analysis, making it ideal for applications involving polymers or low-melting-point materials.
LFA L51 1000
A modular instrument for thermal diffusivity and conductivity measurements, supporting temperatures from RT to 1000°C, optimized for quick measurement cycles and high flexibility, perfectly suited for analyzing ceramics and metals.
LFA L51 1250
Provides accurate measurements at temperatures up to 1250°C with rapid heating and cooling, making it well-suited for thermal analysis applications involving ceramics and metals.
LFA L51 LT
The low temperature version delivers precise measurements from
-100 °C to 500 °C for various applications in the low temperature range.
Sample carriers and holders
Various sample holder types allow the measurement of a broad range of sample dimensions from 3 to 25,4 mm in solid, liquid, powder, or paste form. In addition, sample carriers for phase change materials are available. The Linseis sample robot can measure up to 6 samples simultaneously, with options for up to 18 samples on request. Sample holder materials include graphite, SiC, alumina, or various metals.
Sample carriers
Sample holder
Model selection
Supported model selection
The softwarre allows the selection of various evaluation models. To support the user with the selection, the fit quality of all models can be easily displayed to guarantee an easy handling as well as maximum accuracy.
Empirical data from customers and Linseis application labs worldwide show that the combined Dusza model is the most universally applicable, typically providing the best fit between measurement data and model across a wide range of materials.
Combined Dusza-Model – Unique combined solution of the simultaneous heat loss and finite pulse corrections with the laser flash method
The universal combined model, based on Dusza’s proven method, enables reliable evaluation of laser flash data by simultaneously correcting for heat losses, finite pulse effects, and non-adiabatic conditions. Thanks to non-linear parameter estimation, no manual model selection is needed—saving time and avoiding user error. Tested on over more than 100 samples, the method consistently delivers accurate and highest quality results. The example with an Inconel sample clearly shows: the combined model provides the best fit and highest precision compared to conventional approaches.
Modified combined model / special model for translucent samples
As illustrated in the graph, the temperature rise for translucent samples, generated by the induced energy pulse, results in an immediate signal increase of the detector. This initial signal has to be considered and corrected, as it distorts the measurement result to a seemingly higher thermal diffusivity. Up to now, existing models could not provide a sufficiently good fit for this immediate temperature rise phenomenon. Our unique combined model enables the correction of the sample data and provides an adjusted fit, leading to significantly improved measurement results.
McMasters Model for porous samples
The McMasters Model is a specialized tool designed to analyze heat transfer in porous materials with precision and flexibility.
Key Features:
- One-dimensional heat transfer model for accurate analysis.
- Includes finite penetration depth of the initial pulse as a key fit parameter.
- Accounts for heat losses at both front and rear surfaces of the sample.
This advanced model, based on the work of McMasters et al.,* ensures reliable and detailed results,
making it an essential option for complex thermal investigations.
* McMasters, Robert L. et al. “Accounting for Penetration of Laser Heating in Flash Thermal Diffusivity Experiments.” ASME. J.
Heat transfer (1999): 121(1): 15-21.
Software
Making values visible and comparable
ALL NEW LiEAP Software
The newly developed LiEAP software includes AI-based assistance that minimizes operator errors and reduces measurement uncertainties. Additionally, the software supports various unique models, including the Dusza model, which can handle transparent, porous, liquid, powder samples and multilayer systems.
Main Features
- Fully compatible MS®Windows™ software
- Data security in case of power failure
- Safety Features (Thermocouple break protection, power failure, etc.)
- Online and offline Evaluation of current measurement
- Curve comparison
- Storage and export of evaluations
- Export and import of data in ASCII format
- Data export to MS Excel
- Multi – method analysis (DIL, STA, DSC, HCS, LSR, LZT, LFA)
Programmable gas control - NEW workflow
Cp (Specific Heat) determination by comparative method
To calculate the specific heat capacity, the maximum of the temperature rise in the sample is compared to the maximum of the temperature rise of a reference sample. Both, the unknown and the reference sample are measured under the same conditions in a single run, using the sample robot. So, the energy of the laser pulse and the sensitivity of the infrared detector can be assumed to be the same for both measurements.
Pulse detection
In order to enhance the precision of the Cp meaurement, it is essential to measure the energy of the pulse and the sensivity of the detector, rather than assuming these to be constant.
Therefore, the updated LFA L51 offers the possibilitiey to record the plus shape and detects the pulse shape and perform an energy correction in the fully automated measurement cycle. This results in a highly accurate determination of the specific heat capacity in the comparative measurement mode with a known reference material.
Evaluation Software
- Automatic or manual input of related measure- ment data: such as density and specific heat
- Universal combined evaluation model for data evaluation
- Special models for translucent or porous samples
Evaluation Models
- Dusza combined model
- NEW McMasters model (for porous samples)
- 2-/3-layer models
- Parker
- Cowan 5 and 10
- Azumi
- Clark-Taylor
- Degiovanni
- Finite pulse correction
- Heat loss correction
- Baseline correction
- Multilayer model
- Determination of contact resistance
- Correction for translucent samples
Measurement Software
- Easy and user-friendly data input for tempera- ture segments, gases etc.
- Controllable sample robot
- Software automatically displays corrected measurements after the energy pulse
- Fully automated measurement procedure for multi sample measurements
- Costumer support
- Easy mode for efficent and fast measurements
- Expert mode for maximum individualisation
- Service model monitors the device mode and provides feedback
Applications
Ceramics & Glas
Glass and ceramics are essential materials in both traditional and high-tech applications. From household items to advanced components in electronics, aerospace and medical technology, their unique mechanical, thermal and chemical properties enable versatile use under demanding conditions.
Thermal analysis methods play a crucial role in material development and process optimization. They provide precise insights into thermal conductivity, heat capacity, thermal expansion and sintering behavior. This allows manufacturers to fine-tune compositions, improve energy efficiency and ensure product performance across a wide range of glass and ceramic materials – including technical ceramics, smart surfaces and fiber-reinforced composites.
Application example: Thermal conductivity, thermal diffusivity and specific heat capacity of glass ceramics
BCR 724, a standard glass ceramic has been measured using LFA L51 500 / 1000. Therefore, a small disc of 1mm thickness and 25.4mm diameter was cut out of a plate of bulk material and coated with graphite for the measurement. The LFA L51 gives the thermal diffusivity as a direct function of temperature. The Cp data was obtained in a comparative way by measuring a known ceramic standard under the same conditions in a second sample position of the same sample holder. Using this, the thermal conductivity was calculated out of the product of density, specific heat and thermal diffusivity. The result shows a slightly decreasing thermal diffusivity and conductivity while the Cp value increases over temperature.
Application example: Thermal diffusivity of glass ceramic
Pyroceram, a glass ceramic trademark of Corning used as a standard material in various applications, has been measured using the LFA L51 1250 to show the reproducibility of thermal diffusivity values. In total 18 measurements were performed with 18 samples that were cut out of one bulk block. Each sample was measured separately and the result shows a spread in the result that is in a range of +/- 1 % in a temperature range up to 1160°C.
Research, Development and Academia
New materials play a crucial role in technological innovation – from lightweight composites in aerospace to advanced ceramics and semiconductors. Their development requires detailed knowledge of thermophysical properties such as thermal diffusivity, thermal conductivity and specific heat capacity.
The LINSEIS LFA systems provide fast, non-destructive and precise measurement of these key parameters. This makes them essential tools in material research and development, especially for polymers, ceramics, hybrid materials and high-temperature alloys. With accurate LFA data, researchers can optimize heat flow, improve performance under thermal stress and support the development of safer, more efficient and sustainable materials.
Application example: Thermal conductivity of graphite
A graphite sample has been investigated using the LFA L51. Thermal diffusivity has been determined directly at several temperature between RT and 1000°C. Specific heat capacity has been determined using a known graphite standard in a second sample position as a reference in the same measurement. The product out of diffusivity, specific heat and density gives the corresponding thermal conductivity. The result shows a linear decreasing thermal conductivity which is typical and a thermal diffusivity that is showing a plateau above 500°C. The Cp is slightly increasing over temperature.
Polymers
Polymers are used in countless applications – from packaging and automotive parts to aerospace and medical devices. To ensure reliable performance, understanding their thermal conductivity, specific heat and thermal diffusivity is essential, especially when it comes to thermal insulation, cooling behavior or aging resistance.
The LINSEIS LFA systems enable accurate, non-destructive analysis of these key properties across all polymer types – including thermoplastics, thermosets and elastomers. Whether for product development, quality control or material comparison, LFA measurements help optimize processing conditions and support the selection of the right material for each application.
Application example: Thermal Conductivity of Polymers
PTFE is a versatile material widely used in industries such as chemical processing and petrochemicals for applications like vessel linings, seals, gaskets, and washers due to its chemical inertness and corrosion resistance. In this study, a PTFE sample was measured using the LFA L51 500 up to 150°C in an inert atmosphere. Thermal conductivity was derived from specific heat and density change data recorded via dilatometer and DSC. The thermal conductivity remains stable across the temperature range, except around 30°C, where a solid-state phase transition occurs.
well informed
