Today the sensitivity of sensor arrays like CCDs and focal plane arrays (for example for the infrared region) can reach the single photon detection limit. For sensing systems the adaptation of the set up to the signal generation as well to its detection is a challenge. We use multi-spot laser sources for illumination, and spatial light modulators for multiplexing of signals, for selection and parallelization of the signal detection. The group deals with sensor systems especially for spectral sensing as well as for micro imaging.

A principal spectral sensing arrangement consists of an entrance slit or an entrance slit array (one and two dimensional) a diffractive element like a grating and a two dimensional CCD. This is called a double array spectrometer: A set of different spectrometer functions can implemented in one set up. So a parallel detection of different signals is possible. The throughput and the signal-to-noise ratio can be increased. Imaging aberrations can be avoided be using a set of different imaging positions. Sub-pixel generation and sub-pixel analysis is possible. The arrangements are very compact or miniaturized. Examples are miniaturized HADAMARD spectral sensors for space, different RAMAN spectral sensors for biotechnology, highly parallel spectral PCR-readers (multi-signal reader) and multi-object spectrometers.

For imaging the holographic principal uses a coherent illumination of the sample by a spherical wave of a pinhole and for detection of the interferogram a CCD. The principal is extended by using a pinhole-array. Lens-less micro-imaging is realised by a multi-spot source generated by diffractive optical elements and by a pinhole array

Fields of work:

• For subsystems and photonic instruments we design and manufacture transmissive optical fixed and switchable arrays (MEMS spatial light modulators). The structure size is > 2 µm and the contrast ratio is better than 1 : 10000.
• Design of compact and high performance spectral sensors. Examples are a compact UV Raman-spectral sensor and a HADAMARD spectrometer for space to detect ozon.
• Theory of detector noise limited HADAMARD and photon noise multiplexing.
• Lens-less microscope for point-of-care cell imaging.

Deutsch | English