Recently we proposed frequency division multiplexed imaging (FDMI), which allows capturing multiple images in a
single shot through spatial modulation and frequency domain filtering. This is achieved by spatially modulating the
images so that different images or sub-exposures are placed at different locations in the Fourier domain. As long as there
is no overlap of the individual bands, we can recover different components by band-pass filtering the multiplexed image.
In this paper, we present a Texas Instruments DMD based implementation of FDMI. An image is formed on the DMD
chip; pixels are modulated by the micro-mirrors; and the modulated image is captured by a camera. By applying
modulation during a sub-exposure period, the corresponding sub-exposure image is at the end recovered from the fullexposure
image. Such a system could be used in a variety of applications, such as motion analysis and image deblurring.
We will provide experimental results with the setup, and discuss possible applications as well as limitations.
In this paper, we describe frequency division multiplexed imaging (FDMI), where multiple images are captured
simultaneously in a single shot and can later be extracted from the multiplexed image. This is achieved by
spatially modulating the images so that they are placed at different locations in the Fourier domain. The
technique assumes that the images are band-limited and they are placed at non-overlapping frequency regions
through the modulation process. The FDMI technique can be used for extracting sub-exposure information and
in applications where multiple cameras or captures are needed, such as high-dynamic-range and stereo imaging.
We present experimental results to illustrate the FDMI idea.
We present test results from a compact, fast (F/1.4) imaging spectrometer system with a 33° field of view, operating in
the 450-1650 nm wavelength region with an extended response InGaAs detector array. The system incorporates a simple
two-mirror telescope and a steeply concave bilinear groove diffraction grating made with gray scale x-ray lithography
techniques. High degree of spectral and spatial uniformity (97%) is achieved.
The inherently high resolution of imprint lithography has the promise of extending integrated circuit minimum feature sizes down to the 10 nm region. However, the main effort of companies building nanoimprint tools has been directed to the development of robust printing techniques, rather than to alignment. Consequently, no alignment system currently exists for nanoimprint lithography that is capable of the alignment accuracy required by the semiconductor industry. This paper proposes a solution to the problem of obtaining accurate alignment over an extended imprinted area. On the one hand, alignment is difficult to perform when the mold template and the substrate are in contact, or nearly in contact. On the other hand, if they are widely separated, the accuracy is limited by the difficulty of simultaneously imaging fine features on both of them. However, by using orthogonal polarizations, sharp images of the template and substrate can be obtained when they are separated by 30 to 40 μm. Previous experience with a dual focus x-ray alignment microscope indicates that this alignment technique will readily meet the 18 nm 3 σ tolerance required by the semiconductor industry at the 45 nm node. Here the technique is adapted for nanoimprint lithography by employing transparent bulk mold materials (e.g. quartz) with opaque alignment targets on the surface. In addition, a flexure stage capable of reproducibly bringing the mold template and the substrate into contact is integrated into the system, so that after the alignment is performed it can be maintained during imprinting.
It is well known that zone plates can print extremely small features in microlithography. However, the size and complexity of zone plates has limited their application. In this paper simulated and experimental results are presented for simple zone plates with very high performance. It has previously been shown that submicron diameter zone plates, with only 2 or 3 zones, can focus 1 nm wavelength X-rays to less than 40 nm FWHM. A zone plate with two zones is a ring, whose ratio of outer radius to inner radius is about 0.7. This implies dimensions that may be too small for easy control. However, simulations have demonstrated excellent focusing for both clear and opaque rings over a ratio of radii of at least 0.6 to 0.8. For high contrast, 1 nm wavelength zone plates are typically fabricated in 200-300 nm thick gold. This leads to high aspect ratios, which are difficult to pattern. However simulations have shown excellent focusing in much thinner gold. In addition, conditions were found in 30nm to 90 nm thick gold which generate narrow dark "foci." The focusing of linear zone plates was also simulated. Linear zone plates with 3 and 5 zones produced excellent line foci, although linear zone plates with 2 and 4 zones were much poorer. Scaled up experiments in visible light supported both the circular and linear simulation results.
Blazed gratings have been fabricated using gray-scale X-ray lithography. The gratings have high efficiency, low parasitic light, and high groove quality. They can be generated over a considerable depth for use anywhere in the ultraviolet to middle infrared range. They can also be recorded on substrates of considerable curvature.