In many industrial applications, light is a process variable in its own right. A variation in optical power, spectral drift, or temporal instability can be enough to alter the dose delivered in photobiomodulation. Furthermore, this can skew a measurement or make a process unstable and difficult to reproduce.

Radiometric measurements enable the objective quantification of light energy emitted and received, from UV to IR, continuously or in pulses. At Imasolia, we provide radiometric and spectral characterization services tailored to industry. We offer a reproducible approach for R&D, qualification, and quality control.

Radiometry and photometry

Radiometry describes light as physical energy, expressed in absolute units (W, W/m²...), unrelated to human perception.

Conversely, photometry translates this same light according to a physiological weighting, based on the sensitivity of the eye (lm, lux, cd). As a result, two sources may have identical illuminance in lux. However, they produce radically different effects on a sensor or process. This is particularly true when considering UV/IR, spectral distribution, or actual power output.

This is why, in most applications involving machine vision, material characterization, UV, lasers, or sensor instrumentation, radiometry is the most relevant metrological reference.

What radiometric measurements can we perform?

The most commonly used radiometric measurements in industry are optical power (W), irradiance (W/m²), fluence (J/cm²), spectral analysis (UV–IR), and temporal characterization of pulses.

Power

Optical power represents the total energy emitted by a light source (expressed in watts). It is a key indicator for comparing sources (or batches) under identical conditions, detecting aging drift, qualifying a lighting architecture, or validating a design (sensor margin/saturation). For a robust approach, it is measured in a controlled geometry and with a stable instrumented chain. In addition, these measurements can be performed on both continuous and pulsed lighting.

Irradiance

Irradiance (sometimes called energy illuminance) corresponds to the power received per unit area (W/m²). It is the key quantity when linking light to a process effect: UV exposure (polymerization, photoreticulation, accelerated aging), sensor response (camera, photodiode, multispectral sensors), optical measurements on materials (scattering, fluorescence, reflectance) or quality control with reproducible energy thresholds. In practice, irradiance is often more relevant than total power. This is because it naturally incorporates distance, geometry, and illumination optics (lenses, diffusers, guides, etc.).

Fluence

In dose-dependent applications, fluence (or energy dose), expressed in J/m², becomes the reference quantity. It quantifies the energy deposited on the target over a given period of time. It therefore makes it possible to define robust compliance criteria, incorporating both irradiance and exposure time. This measurement is often used to characterize photobiomodulation processes.

Spectroscopy

Spectral measurement describes the distribution of power as a function of wavelength. It is used to verify source-sensor compatibility (sensitivity, filters, optical windows), control a useful band, identify spectral drift related to temperature or aging, and analyze fluorescence or absorption phenomena. Furthermore, in an industrial context, the spectrum is a decision-making tool for choosing a source, defining tolerances, and ensuring stability and reproducibility.

Pulse characterization

Finally, many industrial systems operate in pulse mode (camera-synchronized strobes, high-intensity flashes, rapid controls). Under these conditions, performance is not solely a matter of light quantity, but also depends on when it is delivered and its repeatability. It therefore becomes essential to characterize the pulse duration, energy per pulse, jitter, and temporal stability. In addition, repeatability over N cycles must also be examined, as well as consistency with sensor or PLC triggering. Often, this type of variation explains intermittent defects in production. This happens when the machine stalls for no obvious reason.

Measurement platform: Luminia and Visolia

Imasolia relies on a modular optical characterization solution designed for industrial environments: Luminia, combining power, spectrum, and pulse measurements with Visolia control and analysis software.  

Designed for industrial requirements, this customizable radiometry system is based in particular on:

• homogeneous capture via an integrating sphere, in order to control geometric effects,
• qualified and traceable sensors ( ISO 17025 level),
• rapid and reproducible acquisition,
• simple data utilization (analysis and export).

When should a radiometric measurement campaign be carried out?

A radiometric measurement campaign becomes relevant as soon as light directly influences the performance of a system or the reproducibility of a process. It is particularly recommended for validating lighting before machine integration, auditing production drift (unexplained performance decline), comparing several suppliers or batches, implementing quality control on continuous lighting or flashes, or qualifying a UV process, spectroscopy chain, or sensor system through radiometric measurements.

Depending on your objective (comparative, diagnostic, or qualification), the service is structured to provide immediately actionable results. You receive a decision-oriented summary (measured values, compliance, deviations, and drifts). In addition, you will receive the essential curves (spectrum, energy, stability), all exportable data (CSV), and concrete recommendations (thresholds, tolerances, measurement protocol). In this way, the objective is clear: to make light a controlled and traceable variable, rather than a factor of uncertainty.

Need a radiometric measurement?

Imasolia helps you characterize your light sources, whether continuous or pulsed, through comprehensive radiometric and spectral measurements: optical power, irradiance, fluence, spectrum, and temporal dynamics.

Depending on your organization, we can perform these measurements for you as part of a service. We can also provide you with a customized Luminia measurement bench so that you can integrate optical characterization directly into your qualification and control processes.

Contact us to discuss your needs, define the appropriate measurement protocol, and receive a technical proposal with pricing.