Abstract: Methods of determining an optimal focus height are disclosed. In one arrangement, measurement data from a plurality of applications of the metrology process to a target are obtained. Each application of the metrology process includes illuminating the target with a radiation spot and detecting radiation redirected by the target. The applications of the metrology process include applications at different nominal focus heights. The measurement data includes, for each application of the metrology process, at least a component of a detected pupil representation of an optical characteristic of the redirected radiation in a pupil plane. The method includes determining an optimal focus height for the metrology process using the obtained measurement data.

Abstract: Methods of determining an optimal focus height are disclosed. In one arrangement, measurement data from a plurality of applications of the metrology process to a target are obtained. Each application of the metrology process includes illuminating the target with a radiation spot and detecting radiation redirected by the target. The applications of the metrology process include applications at different nominal focus heights. The measurement data includes, for each application of the metrology process, at least a component of a detected pupil representation of an optical characteristic of the redirected radiation in a pupil plane. The method includes determining an optimal focus height for the metrology process using the obtained measurement data.

Abstract: A coronary stent is provided with asymmetric drug releasing controlled coating used in interventional therapy of coronary disease, containing a bare stent and a coating consisting of drug and carrier, the coating is coated onto the outer wall surface of the bare stent, and is multi-layered. The drug concentration in the coating increases in sequence from the outer layer to the inner layer. The drugs used in different layers of the coating may be identical or different, and particularly may be one or more selected from taxol, rapamycin, heparin, docetaxel and a combination thereof. The carrier may be a random (lactide-glycolide) copolymer having a molecular weight of 50,000-200,000. The drug-coated stent of the present invention employs highly effective drugs, enabling a thinnest coating and reducing the vascular irritation. The drug release is regulated by altering the coating manner so as to satisfy the clinical requirement for controlled drug release.

Abstract: A coronary stent is provided with asymmetric drug releasing controlled coating used in interventional therapy of coronary disease, containing a bare stent and a coating consisting of drug and carrier, the coating is coated onto the outer wall surface of the bare stent, and is multi-layered. The drug concentration in the coating increases in sequence from the outer layer to the inner layer. The drugs used in different layers of the coating may be identical or different, and particularly may be one or more selected from taxol, rapamycin, heparin, docetaxel and a combination thereof. The carrier may be a random (lactide-glycolide) copolymer having a molecular weight of 50,000-200,000. The drug-coated stent of the present invention employs highly effective drugs, enabling a thinnest coating and reducing the vascular irritation. The drug release is regulated by altering the coating manner so as to satisfy the clinical requirement for controlled drug release.