Abstract: Disclosed herein is a substrate stack comprising a plurality of substrates, wherein: each substrate in the substrate stack comprises at least one alignment opening set; the at least one alignment opening set in each substrate is aligned for a light beam to pass through corresponding alignment openings in each substrate; and each substrate comprises at least one alignment opening that has a smaller diameter than the corresponding alignment openings in the other substrates.

Abstract: Disclosed herein is an electron-optical assembly testing system for testing an electron-optical assembly, the system comprising: a source of charged particles configured to emit a beam of charged particles; an electron-optical assembly holder configured to hold an electron-optical assembly to be tested such that, when the system is in use with an electron-optical assembly held by the electron-optical assembly holder, the electron-optical assembly is illuminated by the beam; and a sub-beam detector for detecting sub-beams of charged particles that have been transmitted through the electron-optical assembly.

Abstract: The present invention provides two-component polyurethane compositions comprising, as one component, polyisocyanate compositions of the isocyanurate of one or more bis(isocyanatomethyl)cyclohexane or, preferably, a mixture of two or more of these, and of the isocyanurate of hexamethylene diisocyanate (HDI trimer), and, as the other component, a mix of a soft polyol having a hydroxyl functionality of from 2.5 to 5.0 and a molecular weight of from 500 to 3,000, and a hard polyol. Such compositions provide coatings, especially clear topcoats, which exhibit excellent scratch and mar and solvent resistance in addition to a good balance of hardness and flexibility without the need for increasing the volatile organic content (VOC) of the compositions. Also provided are compositions of a polyisocyanate compositions of the isocyanurate of one or more bis(isocyanatomethyl)cyclohexane with soft polyol which have lower VOCs.

Abstract: The present invention provides two-component polyurethane compositions comprising, as one component, polyisocyanate compositions of the isocyanurate of one or more bis(isocyanatomethyl)cyclohexane or, preferably, a mixture of two or more of these, and of the isocyanurate of hexamethylene diisocyanate (HDI trimer), and, as the other component, a mix of a soft polyol having a hydroxyl functionality of from 2.5 to 5.0 and a molecular weight of from 500 to 3,000, and a hard polyol. Such compositions provide coatings, especially clear topcoats, which exhibit excellent scratch and mar and solvent resistance in addition to a good balance of hardness and flexibility without the need for increasing the volatile organic content (VOC) of the compositions. Also provided are compositions of a polyisocyanate compositions of the isocyanurate of one or more bis(isocyanatomethyl)cyclohexane with soft polyol which have lower VOCs.