Dual aperturing

Figure 3.9 Synchrotron IR spectrum of a brain cut (5 p,m thickness), recorded in reflection mode, using a dual aperture of 3 x 3 p,m2, 64 scans at 8 cm-1 resolution.

Figure 3.10 (a) Optical image of gold wires which have been coated on a silicon wafer. The gold layers are themselves covered with a thin polymer film, (b) Chemical image of the polymer overlayer (peak height of the vas CH2, at 2920 cm-1), recorded with a dual aperture of 3 x 3 pm2, 64 scans at 4 cm-1 resolution. 

Figure 1.4 Dual-aperture microscope similar to the optics of an IRPlan microscope. Reproduced with permission from Ref [25],...

Spatial resolution can be inaeased by introducing a dual aperturing (Redundant, Spectra-Tech). In this case, two apertures of identical size are placed at the source and sample images. This technique reduces the stray light by a factor of 3 [183] by reducing the illuminated spot at the sample. 

Figure 7.5 Radial integration of the optical sensitivity for a model Schwarschild objective when used in a standard (single-aperture) configuration (solid curve for the encircle intensity) and for the dual-aperture confocal configuration (dashed curve). A wavelength of 6 pm and Schwarschild optic having NA = 0.65 were assumed.

The excitation lamp is enclosed within a compartment which is designed to shield the detector and its associated electronic circuits from the heat generated by the lamp. A small fan flushes cool air into the upper compartment that houses the detection devices. The trigger mounted at the instrument s handle is used to operate a dual shutter that opens and closes the excitation and emission apertures simultaneously. The hand-held instrument is low cost (a/ 2,000), simple to operate, and weighs only a little over 1 kg without the power supply ( 5 kg). A photograph of the prototype instrument is shown in Figure 2. 

In order to improve volume efficiency and reduce payload weight for earth-orbital remote-sensing applications, low-mass membrane-based synthetic aperture radar array concepts are being developed. One such system is an inflatable deployable SAR consisting of thin fabrics or membranes that are deployed for L-band operation with dual polarisation. The entire assembly is flexible before employment and is rolled up onto the spacecraft bus. The antenna comprises three membranes positioned vertically over one another the ground plane, the radiation patch, and the microstrip transmission line membranes74. 

As mentioned above, the iron phosphate-oxalate layers in this material are cross-linked by the (out-of-plane) oxalate units as in most of the phosphate-oxalates. It is interesting that similar dual functionality has also been observed in the zinc oxalate described earlier. The zinc oxalate also contains both the inplane and out-of-plane oxalate linkages to create three-dimensional connectivity, and possessing channels [45]. In Fig. 7.38, we show the structure of this material to illustrate the presence of the oxalates within the layers as well as a bridge between the layers. This dual functionality of the oxalate units, in the Zn oxalate, gives rise to an elliptical aperture made by the linkages between 10 Zn and 10 oxalate units within the same plane, with the other oxalate unit... 

A dual-iidet ESI source, the LockSpray , was introduced by Waters, based on the rotating aperture of the MUX-source, for the co-introduction of a reference compoimd to act as a lock-mass for accurate-mass determination [65-66]. Dual-inlet devices to introduce a lock-mass compound have also been reported for sector [67] and Fourier-transform ion-cyclotron resonance MS (FT-ICR-MS) instruments [68]. 

Figure 1.7 Dual confocal aperturing achieved with a single physical aperture. Reproduced from Infrared Fourier Transform Spectrometry by P. R. Griffiths and ). A. de Haseth 2007, p. 307.

Several of the procedures described in the previous sections can be advantageously carried out with double barrel tips. Such a probe consists of two capillaries (see Sec. V.B), one of which acts as the potentiometric sensor, while the other is used to determine the tip-substrate distance. For example (79), a gallium microdisk was combined with an ion-selective (K+) potentiometric probe to image K+ activity near the aperture of a capillary (see Fig. 7). Similarly (77), a double barrel tip with one channel as an open Ag/ AgCl micropipette for solution resistance measurement and the other channel as an ion-selective neutral carrier-based microelectrode for potentiometric measurements was successfully used to image concentration distributions for NH4 (Fig. 8) and Zn2+ (Fig. 9). While dual-channel tips facilitate the approach of the substrate and permit a direct determination of the absolute tip-substrate distance, their difficult fabrication severely limits their use. Reference 80 compares the above methods. 

FIGURE 7.18 Cross section of (a) a circularly shielded dual-plane waveguide with three microstrip lines, and (b) a two-layered four-element cylindrical cavity-backed aperture... 

Figure 9.9 PROLITH simulation of reflectivity of single-layer BARC (ARC 29A from Brewer Science) and dual-layer BARC, comprising a top layer (SHB) with n 1.63, k 0.13 and a bottom layer (ODL) with n 1.5, k 0.3, both from Shinetsu. Exposure wavelength 193 nm. Target feature 50-nm lines per space at 100 nm pitch. Numerical aperture of exposure tool 1.35. (Courtesy of Ryoung-han Kim.)...

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