Abstract: Provided is a method for producing a positive electrode active material for an alkali ion secondary battery, the positive electrode active material containing a large amount of a transition metal and enabling operation of the battery. In the method for producing a positive electrode active material for an alkali ion secondary battery, in which the positive electrode active material contains 34 mol % or more of CrO+FeO+MnO+CoO+NiO, the method includes: a step of preparing a positive electrode active material precursor containing crystals; and a step of irradiating the positive electrode active material precursor with light to melt the crystals and amorphize at least a portion of the positive electrode active material precursor.

Abstract: The method of the present invention is used to measure overlay accuracy between a first pattern including a plurality of marks formed on a substrate and a second pattern including a plurality of marks formed on the first pattern. First overlay accuracy is measured by using an erected image of a combination of marks of first and second patterns corresponding to each other. Second overlay accuracy is measured by using an inverted image of the combination of marks. Third overlay accuracy is measured by using an erected image or an inverted image of the combination of marks. Differences between the first overlay accuracy measured by using the erected image and the second overlay accuracy measured by using the inverted image are respectively obtained with respect to some combinations of marks of first and second patterns. An average of the differences is calculated.