We present an integrated array imaging system based on a stack of microlens arrays. The microlens arrays are manufactured by melting resist and reactive ion etching (RIE) technology on 8’’ wafers (fused silica) and mounted by wafer-level packaging (WLP)1. The array imaging system is configured for 1X projection (magnification m = +1) of a mask pattern onto a planar wafer. The optical system is based on two symmetric telescopes, thus anti-symmetric wavefront aberrations like coma, distortion, lateral color are minimal. Spherical aberrations are reduced by using microlenses with aspherical lens profiles. In our system design approach, sub-images of individual imaging channels do not overlap to avoid interference. Image superposition is achieved by moving the array imaging system during the exposure time. A tandem Koehler integrator illumination system (MO Exposure Optics) is used for illumination. The angular spectrum of the illumination light underfills the pupils of the imaging channels to avoid crosstalk. We present and discuss results from simulation, mounting and testing of a first prototype of the investigated array imaging system for lithography.
In this paper we present chromatic confocal distance sensors for the parallelized evaluation at several lateral positions.
The multi-point measurements are performed using either one- or two-dimensional detector arrays. The first sensor combines
the concepts of confocal matrix sensing and snapshot hyperspectral imaging to image a two-dimensional array of
laterally separated points with one single shot. In contrast to chromatic confocal matrix sensors which use an RGB detector
our system works independently from the spectral reflectivity of the surface under test and requires no object-specific
calibration. Our discussion of this sensor principle is supported by experimental results. The second sensor is a multipoint line sensor aimed at high speed applications with frame rates of several thousand frames per second. To reach this evaluation speed a one-dimensional detector is employed. We use spectral multiplexing to transfer the information from different measurement points through a single fiber and evaluate the spectral distribution with a conventional spectrometer. The working principle of the second sensor type is demonstrated for the example of a three-point sensor.
In this paper we show that it is possible using optical photolithography to obtain micron and submicron features for
periodic structures in non-contact using the Talbot effect. In order for this effect to work it is important to have good
control of the illumination light and here we show that the MO Exposure Optics (MOEO) developed by SUSS
MicroOptics provides uniform and well collimated illumination light suitable for Talbot lithography. The MOEO can
easily be incorporated into a standard mask aligner. Here we show 1μm and 0.65μm diameter holes in a hexagonal array
in photoresist made in large-gap proximity printing.
Dispersion causes the focal lengths of refractive and diffractive optical elements to vary with wavelength. In our contribution
we show how it can be used for chromatic encoding and decoding of optical signals. We specifically discuss how
these concepts can be applied for the implementation of systems with applications in the growing fields of hyperspectral
imaging and chromatic distance coding. Refractive systems as well as hybrid combinations of diffractive and refractive
elements are used to create specific chromatic aberrations of the sensors. Our design approach enables the tailoring of the
sensor properties to the measurement problem and assists designers in finding optimized solutions for industrial applications.
The focus of our research is on parallelized imaging systems that cover extended objects. In comparison to point
sensors, such systems promise reduced image acquisition times and an increased overall performance. Concepts for
three-dimensional profilometry with chromatic confocal sensor systems as well as spectrally resolved imaging of object
scenes are discussed.
Speckle fields are formed when quasi-monochromatic light is scattered by an optically rough surface. These fields
are usually described by reference to their first and second order statistical properties. In this paper we review
and extend some of these fundamental properties and propose a novel technique for estimating the refractive
index of a smooth sample. Theoretical and experimental results are presented. Separately, we also report on
a preliminary experiment to determine some characteristics of speckle fields formed in free space by a rotating
compound diffuser. Some initial measurements are made where we examine how the speckle intensity pattern in
the output plane changes as a function of the relative rotation angle.