Innovative sensor solutions for Industry 4.0

In the future, indus­try will become increas­ing­ly dig­i­tal, effi­cient and auto­mat­ed. Autonomous dri­ving sys­tems and robots will facil­i­tate the work of humans in the process. To make this vision a real­i­ty, the Fraun­hofer Insti­tute for Pho­ton­ic Microsys­tems IPMS is devel­op­ing sen­sors, opti­cal com­po­nents and actu­a­tors based on micro­electro­mechan­i­cal sys­tems that detect the envi­ron­ment and make inter­ac­tion safe. In this con­text, sen­sor tech­nol­o­gy is becom­ing the sen­so­ry organ of dig­i­ti­za­tion: it forms the inter­face between machine and human. The insti­tute is now pre­sent­ing some of its lat­est devel­op­ments — such as inno­v­a­tive vec­tor scan­ner mod­ules — at LASER World of PHOTONICS in Munich.

Micro­elec­tron­ics and microsys­tems tech­nol­o­gy are key tech­nolo­gies and enablers for a wide range of appli­ca­tions. For exam­ple, minia­tur­ized, intel­li­gent and net­worked sen­sors and actu­a­tors form the basis for IoT, Indus­try 4.0 and numer­ous future appli­ca­tions with arti­fi­cial intel­li­gence. Fraun­hofer IPMS is now pre­sent­ing some of the lat­est research work on the top­ic of sen­sor tech­nol­o­gy at the 25th World’s Lead­ing Trade Fair for Pho­ton­ics Com­po­nents, Sys­tems and Appli­ca­tions — LASER World of PHOTONICS in Munich from April 26 to 29.

Customized highly miniaturized MEMS scanners

The insti­tute has many years of expe­ri­ence in the devel­op­ment and pro­duc­tion of cus­tomized, high­ly minia­tur­ized MEMS scan­ners. The devices fea­ture large scan angles and high scan fre­quen­cies and show excel­lent long-term sta­bil­i­ty. A qual­i­fied CMOS-com­pat­i­ble bulk micro­ma­chin­ing process is used to man­u­fac­ture 1D and 2D microscan­ners in small and medi­um vol­umes. The eye-safe demon­stra­tor, which will be pre­sent­ed at the show, illus­trates the pos­si­ble oper­at­ing modes of a 2D MEMS scan­ner with qua­si-sta­t­ic out­er axis and res­o­nant inner axis. Appli­ca­tions of this tech­nol­o­gy can be found in scan­ning imag­ing, laser scan­ning microscopy, endoscopy, LiDAR sens­ing for autonomous dri­ving or in head-up dis­plays, head-mount­ed dis­plays as well as AMR displays.

Presentation of the first vector scanner modules with electronics

New in the port­fo­lio of MEMS microscan­ners of Fraun­hofer IPMS are hybrid 2D vec­tor scan­ner mod­ules with elec­tro­mag­net­ic dri­ve. Here, Fraun­hofer IPMS builds on many years of expe­ri­ence in the fab­ri­ca­tion of gim­baled, mono­lith­ic 2D MEMS scan­ner mir­rors and com­bines this with exist­ing know-how in MEMS microassem­bly technologies.

“This new approach sig­nif­i­cant­ly expands the para­me­ter space of pre­vi­ous mono­lith­ic scan­ners. At the same time, the estab­lished advan­tages of Fraun­hofer IPMS scan­ner mir­ror tech­nol­o­gy — high opti­cal pla­nari­ty and decou­pling of the scan axes through gim­bal sus­pen­sion as well as the fatigue-free nature of the spring ele­ments — are retained. The new com­po­nents allow 2‑dimensional qua­si-sta­t­ic deflec­tion at larg­er mir­ror aper­tures as well as a high vec­to­r­i­al posi­tion­ing speed.”

- Dr. Jan Grahmann

The mod­ule also pro­vides the mir­ror posi­tion in the form of ana­log sig­nals in order to be able to real­ize a con­trolled sys­tem. The known addi­tion­al fea­tures such as the appli­ca­tion of a cus­tomized, high­ly reflec­tive dielec­tric mir­ror coat­ing or the real­iza­tion of the mir­ror plate as a dif­frac­tion grat­ing are also fea­si­ble for these com­po­nents. In order to exploit the per­for­mance of the scan mod­ule, it is advis­able to con­trol the com­po­nent in a con­trolled manner.

The required con­trol algo­rithms, which are fine­ly adapt­ed to the mechan­i­cal prop­er­ties of the mod­ule, were devel­oped at the insti­tute and can be trans­ferred to the dig­i­tal con­trol of the cus­tomer’s sys­tem elec­tron­ics (FPGA or micro­con­troller). In addi­tion, com­pact con­trol elec­tron­ics with a pre­cise ana­log dri­ver stage and input stages for the posi­tion sig­nals are avail­able. It can be addressed both anal­o­gous­ly and via a dig­i­tal interface.

Quantum cascade laser with extreme resolution enhancement for spectrometry

Fur­ther research work is con­cerned with the sen­so­ry detec­tion of the envi­ron­ment by means of quan­tum cas­cade laser spec­troscopy. The minia­tur­ized quan­tum cas­cade lasers devel­oped joint­ly with the Fraun­hofer Insti­tute for Applied Sol­id State Physics IAF cov­er a large wave­length range and a broad spec­tral tun­ing range at a high scan rate. The micro­me­chan­i­cal­ly fab­ri­cat­ed dif­frac­tion grat­ing serves as an exter­nal res­onator of the vari­able fre­quen­cy quan­tum cas­cade laser. It allows tun­ing of laser wave­lengths at selec­table speeds or by mov­ing to wave­lengths and hold­ing them for select­ed peri­ods of time. Spec­tral ranges can also be tuned with­out mode hop­ping and there­fore with very high resolution.