Flexible microspectrometer for mobile applications
The fiber-cou­pled microspec­trom­e­ter array maps 39 spec­tra onto a CMOS sen­sor. Cred­it: Fraun­hofer IOF

Researchers at the Fraun­hofer Insti­tute for Applied Optics and Pre­ci­sion Engi­neer­ing IOF have devel­oped a very com­pact spec­trom­e­ter mod­ule. It maps spec­tra from 39 opti­cal fibers onto one cam­era sen­sor in a small space. This is made pos­si­ble by a spe­cial micro-opti­cal sys­tem. The tech­nol­o­gy, which has poten­tial for appli­ca­tions in qual­i­ty assur­ance and ana­lyt­ics, will be pre­sent­ed at ana­lyt­i­ca trade fair in Munich from April 9 to 12.

If you want to spec­tral­ly ana­lyze the light from many dis­tant mea­sur­ing points, you can either use sev­er­al sep­a­rate micro spec­trom­e­ters or com­plex lab­o­ra­to­ry equip­ment. Nei­ther is an option when it comes to flex­i­ble or even mobile appli­ca­tions. A team from Fraun­hofer IOF has now devel­oped a solu­tion in which light is flex­i­bly guid­ed to a sin­gle, very com­pact opti­cal sys­tem using 39 opti­cal fibers. This maps the spec­tral infor­ma­tion onto the image sen­sor of a cam­era.

Micro-optics for spectrometer array

At this year’s ana­lyt­i­ca trade fair, Fraun­hofer IOF is pre­sent­ing a demo sys­tem with the new spec­trom­e­ter optics at booth A3.407. How­ev­er, not much of it can be seen—because it is so small. The researchers from Jena have devel­oped a spe­cial micro-opti­cal sys­tem for pro­cess­ing the light trans­mit­ted via opti­cal fibers. It con­sists of many spec­trom­e­ters arranged next to each oth­er, form­ing what is called as a spec­trom­e­ter array.

Each chan­nel con­tains a prism-grat­ing-prism arrange­ment between achro­mat­ic micro lens­es. The micro lens­es are sep­a­rat­ed by spac­ers to pre­vent crosstalk between the chan­nels. This array arrange­ment allows to mount all spec­trom­e­ter chan­nels at once and results in an opti­cal sys­tem length of less than two cen­time­ters.

Flexible microspectrometer for mobile applications
Thanks to its com­pact design, the microspec­trom­e­ter is robust and can be eas­i­ly inte­grat­ed even in demand­ing envi­ron­ments. Here is an exem­plary visu­al­iza­tion for use in agri­cul­ture Cred­it: Fraun­hofer IOF

Despite the lim­it­ed dimen­sions, the sys­tem maps the spec­trum from around 400 to 800 nanome­ters. A res­o­lu­tion of 0.6 nanome­ters per pix­el is achieved with the cor­re­spond­ing CMOS sen­sor.

Compact optics for quality assurance and analytics

The tech­nol­o­gy has been devel­oped for appli­ca­tions where spec­tral mea­sure­ments are required at many posi­tions or over large areas. This applies, for exam­ple, to the opti­cal analy­sis of coat­ings or print­ings, to par­al­lel mea­sure­ments in bio­an­a­lyt­ics as well as to dig­i­tal agri­cul­ture, e.g., to check the health sta­tus of plants. Thanks to the inte­grat­ed design, the set­up is robust and can be inte­grat­ed into exist­ing sys­tems eas­i­ly.

The team from Fraun­hofer IOF has devel­oped the tech­nol­o­gy to appli­ca­tion matu­ri­ty over three years with the sup­port of the Thüringer Auf­baubank. The task now is to opti­mize it for spe­cif­ic appli­ca­tions with the appro­pri­ate part­ners. For exam­ple, the spec­tral res­o­lu­tion could be adjust­ed, or the spec­tral mea­sur­ing range can be extend­ed to 1,600 nanometers—even dif­fer­ent para­me­ters of the chan­nels are con­ceiv­able.

Pro­vid­ed by
Fraun­hofer-Insti­tut für Ange­wandte Optik und Fein­mechanik IOF

Flex­i­ble microspec­trom­e­ter for mobile appli­ca­tions (2024, April 3)
retrieved 3 April 2024
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