Abstract: White light from a light source is applied onto a wafer through an observation window which is formed on a polishing pad, and a spectrometric analysis is performed to the light which has been reflected on the wafer, whereby a polishing end point of the wafer is detected. In this case, an amount of the reflected light is measured and brightness of the light source is corrected so that the amount of the reflected light is constant. Thereby, the polishing end point is accurately detected.

Abstract: White light from a light source is applied onto a wafer through an observation window which is formed on a polishing pad, and a spectrometric analysis is performed to the light which has been reflected on the wafer, whereby a polishing end point of the wafer is detected. In this case, an amount of the reflected light is measured and brightness of the light source is corrected so that the amount of the reflected light is constant. Thereby, the polishing end point is accurately detected.

Abstract: A method of preserving perishable food in a nonfrozen state in the nonfreezing region below the freezing point of the food, which comprises comparatively rapidly cooling the food from the ordinary temperature to the vicinity of the freezing point of the food and then slowly cooling the food below the freezing point at a cooling rate of 0.01-0.5.degree. C./h, and this method permits perishables such as vegetables, fruits, fishes or shellfishes to be preserved with a high freshness and can suppress without fail any lowering in the freshness thereof which inevitably occurs immediately after harvesting.