Aperture masks

Fig. 2.S. Su mmary of some of the shadow masking and surface-treatment results from 3M. A. Photograph of a polymeric aperture mask [30b] used to pattern a wide range of circuits. This mask bears a 6-inch x 6-inch deposition area, with high open aperture ratio. B. Photomicrograph taken of a one-bit RFID circuit patterned using the polymer shadow mask technology [30c], C. Internal clock signal and the externally demodulated rf, or reader signal of the circuit in B (carrier signal was 125...

The performance of the coded aperture mask is not limited by diffraction effects so that, in principal, there is not an intrinsic limitation to the angular resolution which may be achieved. From a technical point of view the limit is set by the distance between the mask and detector and hence the size of the spacecraft. The size of the pixels within the detection plane also provide another technical limitation to fine angular resolution. However, both mask distance and pixel size do have an indirect influence on the large-scale... 

Fig. 3 a) Schematic view of a solid state Compton telescope (ATHENA type) with a coded aperture mask added for hard X-ray imaging. 

The only true solid-state imager flown to date is the small demonstration instrument of G. Skinner and colleagues at U. Birmingham. It has a 3x3 array of close-packed Ge detectors (1 cm x 1 cm x 6 cm each) and a passive coded-aperture mask (Skinner et al. 1994). The instrument was flown as a piggyback on the GRIS balloon payload in 1993 and produced images of the Crab and Cyg X-1 (Rideout et al. 1994 Sldnner etal. 1994). 

Imaging in the HEXIT experiment will be performed using a coded aperture mask located at 1.5 meter in front of the detector. A rectangular URA mask is planned at present. With the mask element size of 15 x 15 mm the expected angular resolution is arcmin. We are also studying the use of zone-plates for imaging via shadowcasting. 

Mask Unit located at 540 mm from the detector plane and parallel to it, consisting of a static coded aperture mask made from 24x24 mm tungsten elements, 1 mm thick, within a carbon fibre honeycomb plate and support structure. 

The proposed telescope (Aprile et al. 1992a) combines a liquid xenon time projection chamber (LXe-TPC) as calorimeter and position sensitive 7-ray detector with a coded aperture mask to achieve precise measurement of the energy and angular distribution of 7-ray sources in the 0.3-10 MeV energy region (Fig. 1). The coded mask is a 43x41 element URA, with elements... 

ED photoresists are increasingly being successfully applied to photochemical machining processes in the manufacture of products such as colour TV receiver tube aperture masks (shadow masks), integrated circuit lead frames and printing rollers. These resists are used as etch-resists for a variety of metals and alloys, and can withstand the harsh etching conditions used in these processes. 

A casein coating on steel is one step in the manufacture of aperture masks for color TV tubes.Casein is also used as a partial binder in some types of caulking adhesives. 

A lens images the diffracted light onto a wafer with the amount of information collected from the mask by the lens being related to the numerical aperture of the lens with higher NA lenses having higher resolution capability. 

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