# US 9,752,934 B2 · Wavelength calibration method for monochromator

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- Number: US 9,752,934 B2
- Document ID: US9752934B2
- Status: Granted
- Kind: B2
- Application number: 14/478,903
- Filed: 2014-09-05
- Published: 2015-03-12
- Granted: 2017-09-05
- Earliest claimed: 2013-09-06
- Assignees: Shimadzu Corporation
- Applicants: Shimadzu Corporation
- Inventors: Hiroyuki Minato
- Web page: https://patentgrep.com/patent/US9752934B2

## CPC

- G01J 3/18: using diffraction elements, e.g. grating (gratings per se G02B)
- G01J 3/28: Investigating the spectrum (using colour filters G01J3/51)
- G01J 2003/2866: {Markers; Calibrating of scan}
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

Provided is a method for performing a wavelength calibration of a monochromator with a diffraction grating by casting light from a standard light source whose emission intensity contains a change with a predetermined cycle onto the diffraction grating and measuring an intensity of light reflected by the grating. The method includes the steps of: measuring at least two times the intensity of the reflected light from the grating within the aforementioned cycle at each of the rotational positions of the grating corresponding to a range of wavelengths including a peak wavelength of a bright line spectral light generated by the standard light source; determining an intensity value 201 at each rotational position based on all the measured values obtained at the rotational position; and locating, as the peak wavelength of the bright line spectral light, a wavelength at which the intensity value 201 is maximized.

## Claims

### Claim 1

A method for performing a wavelength calibration comprising steps of:
casting light from a standard light source whose emission intensity contains a change with a predetermined cycle due to a use of a power source for the standard light source onto a diffraction grating in a monochromator;
measuring at least two times the intensity of the reflected light from the diffraction grating within the aforementioned cycle at each of rotational positions of the diffraction grating corresponding to a range of wavelengths including a peak wavelength of a bright line spectral light generated by the standard light source;
determining an intensity value at the rotational position based on all measured values obtained at the rotational position; and
locating, as the peak wavelength of the bright line spectral light, a wavelength at which the intensity value is maximized.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the intensity value is a highest of all the measured values.

### Claim 3

A spectrophotometer, comprising:
a) a monochromator having a diffraction grating for receiving and diffracting light from a standard light source for generating a known bright line spectral light whose emission intensity contains a change with a predetermined cycle due to a use of a power source for the standard light source, and a grating driver that rotates the diffraction grating;
b) a light measurer for measuring an intensity of light from the monochromator;
c) a monochromator controller for controlling the grating driver so as to rotate the diffraction grating in steps of a predetermined wavelength within a range including a peak wavelength of the bright line spectral light;
d-1) a measured value obtainer for obtaining at least two times the intensity of light from the monochromator within the aforementioned cycle at each rotational position of the diffraction grating;
d-2) an emission intensity determiner for determining an intensity value at the rotational position based on all measured values obtained by the measured value obtainer at the rotational position; and
e) a peak locator for locating, as the peak wavelength of the bright line spectral light, a wavelength at which the intensity value is maximized within the aforementioned range.

### Claim 4 (depends on 3)

The spectrophotometer according to claim 3, wherein the intensity value is a highest of all the measured values.