Abstract: Provided is a method for reliably and easily measuring a liquid level by selecting an optimal reflection method from among a plurality of reflection methods, depending on growing conditions of a pulled single crystal. The method comprises: setting a plurality of measuring methods having different ways of determining the liquid level; creating, in advance, information that associates with a gap between the outer peripheral face of the single crystal and a predetermined position located between a heat shield and the outer peripheral face of the single crystal; determining the gap in accordance with manufacturing conditions; selecting a measuring method associated to the determined gap, on the basis of the information; and measuring the liquid level of a melt surface in use of the selected measuring method.

Abstract: This invention provides a position measuring method for measuring a surface level of melt in a crucible arranged in the inside of a Czochralski furnace based on a principle of triangulation, in which a light source and a photo detector are provided; light emitted from the light source is applied to the surface of the melt; and the light reflected by the surface of the melt is received by the photo detector, the method comprising: providing a member in the vicinity of the surface of the melt; and causing the emitted light to be reflected by the member, applying the reflected light to the surface of the melt, and causing the light reflected by the surface of the melt to be received by the photo detector.

Abstract: While position measurement of an edge position of a thermal shield takes place in a short time with high working efficiency, the edge position can be measured accurately without variation. First determination takes place while a distance is measured with a first scanning interval. When a change in a measured distance which can be determined as the edge position is determined as a result, an optical scanning position is returned by a predetermined amount reversely to the scanning direction (or reversely to the scanning direction), and while laser beam is scanned again from the returned optical scanning position, second determination takes place while measuring the distance with a second scanning interval shorter than the first scanning interval.

Abstract: Provided is a method for reliably and easily measuring a liquid level by selecting an optimal reflection method from among a plurality of reflection methods, depending on growing conditions of a pulled single crystal. The method comprises: setting a plurality of measuring methods having different ways of determining the liquid level; creating, in advance, information that associates with a gap between the outer peripheral face of the single crystal and a predetermined position located between a heat shield and the outer peripheral face of the single crystal; determining the gap in accordance with manufacturing conditions; selecting a measuring method associated to the determined gap, on the basis of the information; and measuring the liquid level of a melt surface in use of the selected measuring method.

Abstract: While position measurement of an edge position of a thermal shield takes place in a short time with high working efficiency, the edge position can be measured accurately without variation. First determination takes place while a distance is measured with a first scanning interval. When a change in a measured distance which can be determined as the edge position is determined as a result, an optical scanning position is returned by a predetermined amount reversely to the scanning direction (or reversely to the scanning direction), and while laser beam is scanned again from the returned optical scanning position, second determination takes place while measuring the distance with a second scanning interval shorter than the first scanning interval.

Abstract: A melt level or the gap between a melt surface and a heat shield is measured accurately irrespective of how the melt surface is. A laser beam from a range-finding unit is reflected by a scanning mirror and projected on a melt surface through an entrance window and a quartz prism in a chamber of a puller. After specular reflection, the beam forms a measurement spot in the bottom of a heat shield and scatters. Part of the scatter, after specular reflection at the melt surface (secondary reflection), passes through the prism, the entrance window and the scanning mirror to the range-finding unit. The range-finding unit carries out triangulation using the distance between a laser source and a photodetector therein, and the angle of incidence and the angle of the received laser beam.

Abstract: A melt level or the gap between a melt surface and a heat shield is measured accurately irrespective of how the melt surface is. A laser beam (2) from a range-finding unit (8) is reflected by a scanning mirror (24) and projected on a melt surface (3) through an entrance window (18) and a quartz prism (20) in a chamber (17) of a puller. After specular reflection, the beam forms a measurement spot (31) in the bottom of a heat shield (16) and scatters. Part of the scatter, after specular reflection at the melt surface (3) (secondary reflection), passes through the prism (20), the entrance window (18) and the scanning mirror (24) to the range-finding unit (8). The range-finding unit (8) carries out triangulation using the distance between a laser source and a photodetector therein, and the angle of incidence and the angle of the received laser beam.