UV Irradiation Chamber Simulation: Calculating Irradiance

How the UV irradiation chamber simulation works

The simulation reproduces each UV irradiation chamber with its real inner dimensions. Lamps and LEDs are modelled as radiation sources; the reflections at the mirrored side walls enter the calculation via the image-source method. For every point of the measuring plane, the simulation sums the contributions of all sources and their mirror images, yielding the spatial irradiance distribution inside the chamber.

Calculating the irradiance in the UV chamber

After selecting chamber, spectral range (UVA, UVA+, UVB or UVC for the BS chambers, LED wavelength 365–450 nm for the BSL chambers) and power, the simulation calculates the irradiance in mW/cm² or W/m². Optionally, two lamp groups or LED wavelengths with separate power sliders can be combined — for example for mixed UVA and UVB irradiation.

Irradiance distribution and homogeneity

The irradiance distribution on the measuring plane is displayed as a false-colour map, complemented by relative section profiles through the chamber centre. Key figures such as E max and E mean quantify the homogeneity of the illumination. Measuring points can be placed by clicking on the heatmap to read the irradiance at individual positions — for example at sample locations.

Influence of distance and sample height

The height of the measuring plane is freely adjustable — from the chamber floor up to just below the sources. With a smaller distance to the lamps or LEDs, the irradiance increases according to the inverse-square law while the homogeneity usually decreases. The simulation makes this trade-off visible and helps to find the right sample height for uniform irradiation.

Calculating UV dose and exposure time

From the mean irradiance of the measuring plane, the simulation calculates the UV dose as a time integral. After entering a target dose in mJ/cm², it shows the irradiance over time and the switch-off point — including the switch-on behaviour: low-pressure mercury lamps run up slowly, UV LEDs reach their power within a few seconds.

Simulating samples and components with STEP and STL files

Your own samples and components can be loaded into the chamber as STEP or STL files. The model rests centred on the measuring plane, is considered opaque and casts a shadow; the contributions reflected from walls and ceiling are reduced accordingly. The files are processed exclusively locally in the browser — they are neither uploaded nor stored.

Influence of reflections and angle of incidence

The mirrored side walls of the irradiation chambers considerably increase irradiance and homogeneity; the simulation reproduces them via the image-source method with wall-specific reflectances — door and ceiling reflect more weakly than the side walls. In addition, the calculation takes the angle of incidence (cos θ) and the inverse-square law into account for every source contribution.

Lamp and LED models in the simulation

The BS series uses T8 low-pressure mercury lamps, integrated analytically as isotropic line sources — for UVA, UVA+, UVB and UVC. The BSL series uses UV-LED arrays; their emission characteristics come from measured LED models for wavelengths from 365 to 450 nm. The double-sided BS-05 is simulated with separate upper and lower lamp groups.

Assumptions and limits of the simulation model

The internal source arrangement is simplified; diffuse reflection components, reflections at the floor, Fresnel losses at the target surface, spectral effects and ageing of the sources are not taken into account. Details are given in the model description above. The results are orientation data for planning and comparison — they do not replace a measurement and are provided without guarantee.

Selecting and comparing suitable UV irradiation chambers

With BS-02 to BS-05, the BS series covers chambers from compact to large-volume; the BS-05 irradiates from both sides. The BSL series offers UV-LED chambers in several sizes and power classes (HO, ECO, ECO+) with BSL-01i to BSL-04. The simulation makes a direct comparison easy; technical data and accessories can be found on the Opsytec irradiation chambers product page.

Frequently asked questions about the irradiation chamber simulation

Which irradiation chamber suits which application — BS or BSL?

The BS series with low-pressure mercury lamps covers the classic spectral ranges UVA, UVA+, UVB and UVC and is suited to weathering, disinfection and ageing tests. The BSL series with UV LEDs (365–450 nm) switches instantly, is finely dimmable and delivers high irradiance — ideal for UV curing and reproducible dose experiments. The simulation makes both directly comparable.

How accurate are the calculated irradiances?

The simulation provides orientation data: the source arrangement is simplified and the reflection model is fitted to measured distributions. Only a measurement in the real chamber is binding, for example with an Opsytec radiometer.

How do I determine the exposure time for a target dose?

Enter the target dose in mJ/cm² in the dose & time control. The simulation integrates the mean irradiance over time — including the switch-on behaviour of the lamps or LEDs — and shows the switch-off point and the irradiance as a function of time.

Can I simulate my own samples or components inside the chamber?

Yes — load a STEP or STL model; it rests centred on the measuring plane and casts a shadow, and the wall- and ceiling-reflected contributions are reduced as well. The file is processed exclusively locally in the browser and is neither uploaded nor stored.