Neutron Imaging Breakthrough: Achromatic Lens Delivers Sharp Magnified Views

For years, researchers have struggled to capture sharply magnified neutron images of thick, dense objects. The broad spectrum of neutron wavelengths produced by modern sources caused severe chromatic blurring, making it impossible to focus all wavelengths to the same point. Now, a world-first achromatic lens developed at the Paul Scherrer Institute (PSI) in Switzerland eliminates this distortion, enabling crisp, high-resolution imaging inside materials and operating equipment.

Overcoming Chromatic Aberration in Neutron Optics

Traditional neutron lenses suffer from a fundamental optical flaw: different wavelengths refract by different amounts, so blue and red “colours” in a neutron beam converge at distinct focal planes. This chromatic aberration blurs the final image, particularly when magnifying thick samples where a broad spectrum is needed to preserve intensity. PSI’s lens tackles the problem by combining multiple refractive elements made from materials with carefully opposing dispersion properties. The design aligns the focal points across a wide wavelength range, effectively cancelling the colour error without sacrificing transmission. The result is a neutron lens that behaves like an apochromatic system, bringing all useful wavelengths into coincidence to form a single sharp image.

Neutron beams from a spallation source like the SINQ facility at PSI contain a continuous distribution of wavelengths, making chromatic correction especially demanding. The achievement required precise material selection and ultra-smooth surface fabrication tolerances measured in nanometres. While achromatic lenses have long existed for visible light, their adaptation to neutrons – uncharged particles with very different interactions in matter – represents a significant leap in neutron optics.

Enabling In-Operando Studies of Thick Components

The sharp focus unlocks new possibilities for non-destructive examination. Engineers can now peer deep inside bulky machinery, batteries, fuel cells, or geological cores while they operate, tracking dynamic processes such as fluid flow, thermal stress, and chemical reactions. Neutrons are uniquely sensitive to light elements like hydrogen, lithium, and boron, making the lens particularly valuable for monitoring water uptake in concrete, electrolyte distribution in batteries, or hydrogen embrittlement in metals. Previously, achieving comparable clarity required physically sectioning samples or relying on lower-resolution techniques.

The capability to image through centimetres of metal or rock with micrometre-level clarity in real time is a game-changer for industrial quality control and scientific research. For example, an assembled engine can be run while its internal oil flow is visualised, or a fuel cell can be monitored under load to detect degradation patterns. The Paul Scherrer Institute expects the lens to be integrated with existing neutron imaging beamlines at SINQ, expanding their user programme to cover in-operando studies that were previously impossible.

A New Era for Industrial and Scientific Neutron Imaging

Beyond individual experiments, the achromatic lens paves the way for a new class of neutron microscopes. By delivering magnification without blur, it could drive the development of instruments with resolution comparable to laboratory X-ray micro-tomography but with the contrasting abilities of neutrons. Light-element sensitivity and deep penetration make neutrons an essential complement to X-ray and electron microscopy in fields ranging from archaeology to semiconductor packaging.

The lens also benefits large-scale research infrastructure. Facilities such as the European Spallation Source or Oak Ridge National Laboratory’s SNS could adopt similar achromatic designs to enhance their imaging stations. Even small-angle neutron scattering instruments might profit from sharper focusing optics, improving flux on sample. While the PSI prototype is still a research instrument, its successful demonstration signals that the era of truly sharp neutron images has begun.

While the prototype lens has demonstrated clear advantages in laboratory tests, its transition to routine user operations and any eventual commercial production pathway remain to be confirmed. Integration with existing beamline endstations will require further engineering, and long-term stability under high neutron flux must be fully validated.

Why This Matters

This lens eliminates chromatic aberration that has long limited neutron imaging, opening the door to real-time, high-resolution observation inside dense objects. Non‑destructive analysis of light‑element distribution in batteries, engines, and geological samples can now reach micron‑level clarity, potentially accelerating both industrial quality control and fundamental research across materials science and energy technology.

FAQ

Who developed the achromatic neutron lens?

The lens was created by researchers at the Paul Scherrer Institute (PSI) in Switzerland, a leading multidisciplinary research centre. PSI operates the SINQ spallation neutron source where the lens was tested.

What does the lens achieve that previous neutron optics could not?

It brings neutrons of different wavelengths to a common focus, eliminating chromatic blur. This allows a sharp, magnified image to be formed even through centimetres of dense material.

How does the lens improve neutron imaging for thick samples?

By correcting colour error across a broad spectrum, the lens maintains high resolution while using the full neutron intensity. This enables in‑operando studies of processes inside bulky equipment without cutting them open.

When will the lens become available for routine use?

As of now, it is a research prototype. While integration into existing beamlines is planned, a timeline for widespread user operation or commercial availability has not been disclosed.

Sources

• Paul Scherrer Institute (psi.ch)

Source: Optics & Photonics News – Optics, Photonics, Physics News