Academia

Fraunhofer-Insti­tut für Physi­ka­li­sche Messtech­nik IPM

The Fraunhofer Insti­tute for Physi­cal Measu­re­ment Techni­ques IPM develops and resear­ches innova­tive measu­re­ment methods and appli­ca­ti­ons in quantum sensing, with a parti­cu­lar focus on quantum magne­to­me­try and photo­nic quantum sensing. Our long-standing exper­tise in sensor and measu­re­ment system develo­p­ment provi­des the founda­tion for reali­zing indus­trial-grade sensing soluti­ons – from the initial idea and system design through to the final product. The detec­tion of magne­tic fields inside objects is possi­ble through contact­less measu­re­ments from the outside, because magne­tic fields, unlike electric fields, can hardly be shiel­ded. At the same time, this presents a chall­enge for measu­re­ment systems based on magne­tic field sensors, since virtually all objects in our every­day environ­ment generate magne­tic fields of their own (see illus­tra­tion). It is there­fore essen­tial to maintain a high level of control over the magne­tic environ­ment of such measu­re­ment systems. Our goal is to integrate high-resolu­tion magne­tic field measu­re­ments into our systems, enabling the highly precise measu­re­ment of a wide range of obser­v­a­bles relevant to indus­trial appli­ca­ti­ons. The systems develo­ped at Fraunhofer IPM are prima­rily based on optically pumped magne­to­me­ters (OPMs). This type of sensor is charac­te­ri­zed by excep­tio­nal measu­re­ment sensi­ti­vity, limited only by the laws of quantum physics. In contrast to many other quantum-based sensors, OPMs do not require complex cooling infra­struc­ture. Through close colla­bo­ra­tion with partners from science and indus­try, we trans­late insights from quantum research into market-ready techno­lo­gies. Our measu­re­ment systems are built on commer­ci­ally available indivi­dual sensors and are designed to unlock new appli­ca­tion scena­rios, parti­cu­larly in the fields of low-field nuclear magne­tic resonance (NMR) and non-destruc­tive material testing.

Research

  • Quantum Magne­to­me­try: Highly sensi­tive quantum magne­to­me­ters for a broad range of appli­ca­ti­ons in indus­try and research, inclu­ding magne­to­me­tric flow measurement
  • Magne­tic Clean­li­ness: Inves­ti­ga­tion, charac­te­riza­tion, and magne­tic cleaning of space compon­ents and other parts with criti­cal magne­tic properties.
  • Magne­tic Shiel­ding Techno­logy: Inline-capable magne­tic shiel­ding of compon­ents using novel spray-coating processes.
  • Photo­nic Quantum Sensing: Analy­sis and hyper­spec­tral imaging in the infrared range based on nonlinear inter­fe­ro­me­ters using undetec­ted photons

Contact

Dr. Leonhard Braun

Projekt­lei­tung

Website

Freiburg

Activities

How can a fluid whose flow is to be measu­red generate a magne­tic field? And is such a magne­tic field even measura­ble? These questi­ons can only be answe­red by conside­ring the concept of a particle’s spin. Spin is a funda­men­tal property of partic­les such as atoms or atomic nuclei and can be regarded as a tiny magnet that genera­tes its own magne­tic field. Using state-of-the-art quantum-based techno­logy, we can measure this magne­tic field and thereby deter­mine the flow of the fluid.

Magne­tic Flow Measu­re­ment Based on Quantum Sensors

To measure flow rates, we have develo­ped a ground­brea­king method aimed at exten­ding the limits of conven­tio­nal flow measu­re­ment techno­lo­gies. Our approach uses the inher­ent proper­ties of nuclear spins within a liquid as magne­tic markers for precise flow measu­re­ments. The fluid is first magne­ti­zed and subse­quently magne­ti­cally label­led. These magne­tic markers are then detec­ted through a time-of-flight measu­re­ment. Our method differs signi­fi­cantly from approa­ches based on nuclear magne­tic resonance (NMR), as the magne­tiza­tion of the fluid remains static and no charac­te­ristic frequency is genera­ted, as is the case in conven­tio­nal NMR-based measurements.

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In our magne­ti­cally shiel­ded enclo­sure, we measure residual magne­tiza­tion with femto­tesla-level sensi­ti­vity. This enables us, for example, to assess the magne­tic clean­li­ness of compon­ents and systems inten­ded for use in space.

Highly Sensi­tive Measu­re­ment of Magne­tic Cleanliness

The incre­asing use of commer­cial off-the-shelf (COTS) compon­ents in New Space appli­ca­ti­ons helps reduce costs, but also intro­du­ces poten­tial risks. Even minor residual magne­tiza­ti­ons can accumu­late and inter­act with the Earth’s magne­tic field, poten­ti­ally inter­fe­ring with satel­lite attitude control systems and onboard electro­nics. In its magne­ti­cally shiel­ded facility, Fraunhofer IPM can measure and assess the magne­tic clean­li­ness of space compon­ents and assem­blies with sensi­ti­vity in the femto­tesla (fT) range.

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Tailo­red spray coatings enable compact, multi­layer magne­tic shiel­ding solutions.

Spray-Coated Magne­tic Shielding

Conven­tio­nal shiel­ding materi­als such as mu-metal and other high-permea­bi­lity metals are highly effec­tive at low frequen­cies. These materi­als are typically used in the form of sheets or foils, which can intro­duce certain drawbacks, such as overlaps and instal­la­tion seams. Spray-coating techno­logy enables magne­tic shiel­ding to be applied directly to the desired shiel­ding geome­try. Alter­na­ting layers of mu-metal and alumi­nium or copper are deposi­ted onto complex three-dimen­sio­nal geome­tries, ensuring a precise fit. The approach successfully combi­nes the high permea­bi­lity of mu-metal for direct current (DC) and very low frequen­cies with the eddy-current damping provi­ded by conduc­tive metals in the kilohertz (kHz) range and beyond. The result is a seamless, compact broad­band shield that opera­tes from DC up to 100 kHz.

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Corre­la­ted photons enable novel measu­re­ment techni­ques for high-resolu­tion spectro­scopy at low light doses

The Quantum FTIR Spectro­me­ter: Analy­ti­cal Sensing and Hyper­spec­tral Imaging in the Infrared Range

The mid-infrared spectral range conta­ins parti­cu­larly rich infor­ma­tion about the compo­si­tion of a spectro­sco­pic sample. However, detec­tors for this wavelength range are typically techno­lo­gi­cally complex, expen­sive, and often require cooling. In contrast, highly capable and cost-effec­tive silicon detec­tors are available for the visible and near-infrared spectral range. Inter­fe­rence effects of corre­la­ted photon pairs enable infrared spectro­scopy through the detec­tion of visible light. In our Nonlinear Optics and Quantum Sensing team, we are explo­ring how this quantum techno­logy can be used for high-perfor­mance spectro­sco­pic analysis.

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