Résultat de la recherche
Microlens systems for fluorescence detection in chemical microsystems
Micro-optical systems based on refractive microlenses are investigated. These systems are integrated on a chemical chip. They focus an excitation beam into the detection volume (microliter or even submicroliter scale) and collect the emitted light from fluorescent molecules. The fluorescence must be carefully separated by spatial and spectral filtering from the excitation. This paper presents the ray tracing simulation, fabrication, and measurement of three illumination systems. The measurements show that an adroit placement and combination of microfabricated lenses and stops can increase the separation between the excitation light and the fluorescence light. Moreover we present the successful detection of a 20 nM Cy5TM (Amersham Life Science Ltd.) solution in a 100-µm-wide and 50-µm-deep microchannel (excitation volume ≈ 250 pL) using one of these illumination systems. The microchemical chip with the micro-optical system has a thickness of less than 2 mm.
Microlens array imaging system for photolithography
A micro-optical system is proposed that uses a stack of four microlens arrays for 1:1 imaging of extended object planes. The system is based on the concept of multiple-aperture imaging. A compact system is presented that is remarkable in that it provides a diffraction-limited resolution of 3 µm for unlimited object and image areas. Resolution of 5 µm has been demonstrated for an area of 20 × 20 mm2 in an experimental setup using melting resist microlens arrays (190-µm lens diameter). The investigated imaging system was developed in connection with a new contactless photolithographic technique called microlens lithography. This new lithographic imaging technique provides an increased depth of focus (>50 µm) at a larger working distance (>1 mm) than with customary proximity printing. Potential applications are photolithography for large print areas (flat panel displays, color filters), for thick photoresist layers (micromechanics), on curved surfaces (or substrates with poor planarity), in V grooves, etc.