Imaging Spectroscopic Ellipsometer: Accurion EP4
The Accurion EP4 represents the state of the art in Imaging Spectroscopic Ellipsometry, combining ellipsometry, microscopy, and spectroscopy in one instrument. Micrometre-scale lateral resolution and sub-nanometre vertical sensitivity enable quantitative mapping of layer thickness and refractive index.
Manufacturer: Park Systems — South Korea
Overview
The Accurion EP4, developed and manufactured by Park Systems' Accurion Division in Göttingen, Germany, represents the state of the art in Imaging Spectroscopic Ellipsometry (ISE) — a high-precision platform for the quantitative characterisation of thin films, surfaces, and advanced materials. Combining ellipsometry, microscopy, and spectroscopy in a single instrument, the EP4 delivers sensitivity, spatial resolution, and analytical versatility together. With micrometre-scale lateral resolution and sub-nanometre vertical sensitivity, it enables detailed visualisation and quantitative mapping of layer thickness, refractive index, and extinction coefficient, even on microstructured or heterogeneous samples.
Concept of Imaging Ellipsometry
Imaging Ellipsometry combines the polarisation sensitivity of ellipsometry with the spatial resolution of optical microscopy. A microscope objective lens and a camera replace the single-spot detection system of a conventional ellipsometer, so that each pixel becomes an individual measurement point. This pixel-based detection enables quantitative 2D and 3D mapping, real-time contrast imaging, broadband spectroscopic analysis, and precise selection of regions of interest.
From Single-Spot Measurement to Imaging
A conventional ellipsometer returns one averaged result from a single spot of roughly 35 µm. On the EP4 every pixel is its own ellipsometric measurement, with lateral resolution down to 1 µm. This reveals what was previously invisible: local variations in optical properties or film thickness, defects, and hidden features.
Real-Time Ellipsometric Imaging
The EP4 provides a real-time ellipsometric contrast image, enabling intuitive sample navigation and direct region-of-interest selection. Users can visualise surface variations and immediately define precise measurement areas within the live view. This "first find, then measure" workflow makes relevant microstructures and thin-film variations visible instantly, before quantitative Δ/Ψ or thickness mapping is performed.
Superior Performance and User Convenience
Sub-nanometre vertical sensitivity addresses ultra-thin layers across a 190 nm to 1700 nm UV-VIS-NIR spectral range. The intuitive EP4 software suite — EP4Control, DataStudio, and EP4Model — unifies system control, data acquisition, quantitative analysis, and advanced modelling. Automated sample stage control supports large-area stitching, and a built-in active vibration isolation system provides superior mechanical stability.
Modular Optical Design
A modular optical design with interchangeable objective lenses lets the field of view and lateral resolution be matched to each sample. Knife-edge illumination suppresses back-side reflections from transparent substrates, and long-working-distance objectives keep demanding sample environments accessible.
About Accurion
Park Systems GmbH — the Accurion Division in Göttingen, Germany — has built imaging ellipsometers since 1996, originally as Nanofilm Technology, a spin-off of the Max Planck Institute for Biophysical Chemistry. Accurion merged into Park Systems in 2022, joining the world's leading range of nanoscale metrology instruments.
Specifications
| Specification | Accurion EP4 |
|---|---|
| Instrument Type | Imaging Spectroscopic Ellipsometer in PCSA configuration |
| Spectral Range | Max. 190 nm to 1700 nm (UV-VIS-NIR) |
| Lateral Resolution | Down to 1 µm (20× objective lens or higher magnification) |
| Field of View | Typ. 400 µm × 400 µm (10× objective); max. 2 mm × 2 mm (2× objective) |
| Measurands | Delta (0° to 360°); Psi (0° to 360°); Mueller matrix — 11 normalised elements |
| Film Thickness Range | 0 nm to 15 µm (depending on sample and spectral range) |
| Measurement Repeatability | Film thickness 0.005 nm; refractive index n 0.0002 (100 nm SiO₂ on Si) |
| Goniometer | Motorised; AOI range 38° to 90°; angle resolution 0.001°; accuracy 0.01°; speed approx. 5°/s |
| Sample Stage | Max. travel 100/200/300 mm (X/Y); accuracy and precision ≤ 1 µm |
| Z-Axis | Motorised; max. vertical travel 100 mm; accuracy and precision 1 µm |
| Tilt Alignment | Automatic with respect to the plane of incidence; max. tilt range 5°; accuracy and precision 0.001° |
| Vibration Isolation | Built-in active vibration isolation system |
| Software | EP4 suite — EP4Control, DataStudio, and EP4Model |
| Power Supply | 100 V to 240 V~, 50/60 Hz, max. 10 A |
| Environment | Temperature 15 °C to 40 °C; humidity 0% to 60% RH; floor vibration VC-A |