Abstract: A displacement interferometer system comprises: a light source for generating a laser beam of a predetermined wavelength; an incidence unit for allowing the laser beam, generated in the light source to be incident on a target object to be measured; a detector for measuring a distance of the target object to be measured, using a measurement laser beam which is incident on the target object by the incidence unit; and a correction unit connected to the incidence unit so that a correction laser beam is incident in a direction parallel to the measurement laser beam which is incident on the target object to be measured. When the correction laser beam and the measurement laser beam which yaw from an initially set direction are incident in any one direction, the correction unit corrects the correction laser beam and the measurement laser beam to be incident in the initially set direction.

Abstract: There are provided a displacement interferometer system which increases or maximizes productivity, and an exposer using the same.

Abstract: Disclosed is a method for preparing an electrochemical device, comprising the steps of: charging an electrochemical device using an electrode active material having a gas generation plateau potential in a charging period to an extent exceeding the plateau potential; and degassing the electrochemical device. An electrochemical device, which comprises an electrode active material having a gas generation plateau potential in a charging period, and is charged to an extent exceeding the plateau potential and then degassed, is also disclosed. Some electrode active materials provide high capacity but cannot be applied to a high-capacity battery due to the gas generation. This is because a battery using such electrode active materials should be charged to an extent exceeding the gas generation plateau potential in order to realize a high capacity. To solve the problems caused by the gas generation, the battery is charged to an extent exceeding the plateau potential, and then degassed.

Abstract: Disclosed is a pretreatment method for activating an electrode active material having a certain range of potential plateau beyond a redox potential range of a transition metal forming the electrode active material, which comprises charging the electrode active material to an extent exceeding the potential plateau at least once, so as to increase capacity of the electrode active material. Also, disclosed is an electrochemical device comprising the electrode active material activated by the pretreatment method and designed to be subjected to charge/discharge cycles at a voltage lower than the potential plateau. When the electrode active material pretreated by charging it to an extent exceeding the potential plateau is subjected to charge/discharge cycles at a lower voltage, it is possible to significantly increase the capacity of the electrode active material as compared to the capacity of the non-pretreated electrode active material charged/discharged at the same voltage.

Abstract: Disclosed is a secondary battery having a constant-voltage device for preventing the secondary battery from being excessively overcharged. The breakdown voltage of the constant-voltage device is lower than the explosion or ignition voltage of the secondary battery, so the discharge operation may occur before the secondary battery is exploded or ignited even if the voltage of the secondary battery rises above the overcharge voltage, thereby protecting the secondary battery from explosion or ignition. The leakage current value of the constant-voltage device is less than 0.05% of the capacity value of the secondary battery under the maximum charge voltage of the secondary battery, or the breakdown voltage of the constant-voltage device is higher than the maximum charge voltage of the secondary battery. Thus, the constant-voltage device rarely generates the leakage current even if the secondary battery has been charged with the maximum charge voltage.

Abstract: Disclosed are a safety element for a battery, which is provided with material having a Metal-Insulator Transition (MIT) characteristic where resistance abruptly drops at or above a certain temperature, and a battery with such a safety element. This battery with an MIT safety element is turned into a stable discharged state when it is exposed to an elevated temperature or a battery temperature rises due to external impact, so that it can ensure its safety.