Abstract: An SNR calculation method having the steps of measuring the wavelength characteristic of a dynamic range in an optical spectrum measurement apparatus for each wavelength in a multiplexed wavelength range and storing the wavelength characteristic in a storage unit, measuring the signal level and the noise level of a measured optical signal wavelength, reading the noise level of the wavelength of the measured optical signal produced by each of other optical signal wavelengths multiplexed on the measured optical signal wavelength from the storage unit, subtracting the noise level read from the storage unit from the noise level of the measured optical signal wavelength to provide the corrected noise level, and calculating the SNR of the measured optical signal from the measured optical signal level and the corrected noise level.

Abstract: In order to provide a multi-path monochromator capable of reducing the size of optical parts with a high resolution and a wide dynamic range, the multi-path monochromator has a lens 2 used as a first collimator for converting an incident light into a parallel light, a diffraction grating 4 for diffracting an output light outputted from the lens 2, plane mirrors 3 and 5 for reflecting a diffraction light diffracted by the diffraction grating 4 to return the diffraction light back to a same path, a parabolic mirror 7 used as a second collimator for collecting a diffraction light which is again diffracted by the diffraction grating into which a reflected light is again outputted from the plane mirror, and an output slit positioned at a focal position of the parabolic mirror 7. The parabolic mirror 7 used as the second collimator has a focal length which is longer than a focal length of the lens used as the first collimator.

Abstract: An SNR calculation method having the steps of measuring the wavelength characteristic of a dynamic range in an optical spectrum measurement apparatus for each wavelength in a multiplexed wavelength range and storing the wavelength characteristic in a storage unit, measuring the signal level and the noise level of a measured optical signal wavelength, reading the noise level of the wavelength of the measured optical signal produced by each of other optical signal wavelengths multiplexed on the measured optical signal wavelength from the storage unit, subtracting the noise level read from the storage unit from the noise level of the measured optical signal wave length to provide the corrected noise level, and calculating the SNR of the measured optical signal from the measured optical signal level and the corrected noise level.

Abstract: The reference light is entered into the monochromator 4, and by using the diffraction light of the different order from the diffraction order to measure the measured light, the wavelength of the reference light is measured, and the difference between the measured wavelength and the wavelength corresponding to the diffraction order of the reference light is found, and when there is a deviation in the absorption wavelength, the rotation angle of the diffraction grating 14 is corrected by an angle corresponding to the deviated wavelength, and the wavelength is calibrated.

Abstract: The present invention relates to a double pass monochromator that improves wavelength resolution and reduces the actual length thereof. A return reflection means 7 that reverses the direction of dispersion of the wavelength of the second pass light 1c, 1f emitted and incident on a diffraction grating 4 during the reflection. In addition, the angles of the incident and emitted light during separation of spectral components by the diffraction grating are identical during the first and second diffraction.

Abstract: A monochromator including an incident portion upon which light to be measured is made incident; a first lens for converting the incident light to be measured into parallel rays of light; a diffraction grating for receiving the light to be measured converted into the parallel rays of light and for outputting the light at an angle which differs depending on wavelength; a second lens for condensing the output light outputted from the diffraction grating at a certain angle; an output portion for outputting the output light thus condensed; and an angle changing device for making variable at least a relative angle between the diffraction grating and the second lens by one of rotation of the diffraction grating and movement of arrangement of the first and second lenses centering around the diffraction grating.

Abstract: A lateral bipolar transistor includes an insulating substrate, a single crystal semiconductor layer having a first conductivity, a mask layer which has a substantially vertical side surface and which is in contact with the single crystal semiconductor layer, and an insulating sidewall formed along the side surface of the mask layer. A base region is located under the insulating sidewall and formed in the single crystal semiconductor layer. The base region has a second conductivity opposite to the first conductivity and contains an impurity implanted by an ion implantation process. The single crystal semiconductor layer has an underlying portion on which the mask layer and the insulating sidewall are formed. An emitter region is formed in a first portion of the single crystal semiconductor layer other than the underlying portion. A collector region is formed in a second portion of the single crystal semiconductor layer other than the underlying portion.