JPS599523A - Wavelength correcting system for spectrophotometer - Google Patents

Abstract

PURPOSE:To keep wavelength accuracy in an excellent state, by connecting a digital switch to a microcomputer, measuring the displayed error of a known wavelength of a known sample at first, thereafter correcting the wavelength error by manipulating the digital switches. CONSTITUTION:A wavelength scanning motor 20 is rotated by the command from a microcomputer 10, and a wavelength scanning optical element 30 is rotated. When a slider in a scanning mechanism is contacted with a microswitch 4 at a specified position and the switch is operated, a reference position detector 40 sends a signal (a) to the computer 10 so as to stop a wavelength scanning mechanism. A digital switch 50 is connected to the computer 10. When a reference wavelength is set, the computer 10 reads the preset value (b) of the switch 50. When the preset value (b) is zero, setting of the wavelength is performed only by the signal (a). When the preset value (b) is not zero, the wavelength corresponding to the preset value (b) is added to or subtracted from the reference wavelength. Thus the correction of the reference wavelength is performed. In this way, the accuracy of the wavelength can be kept at the excellent state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spectrophotometer using a diffraction grating as an optical element for wavelength scanning, and particularly to a wavelength correction method thereof.

In general, a spectrophotometer capable of wavelength scanning needs to set a reference wavelength for wavelength scanning, and this reference wavelength can be obtained by installing a wavelength scanning optical element at a reference position. -! However, the reference position of the wavelength scanning optical element can be determined by rotating the wavelength scanning motor in one direction and stopping it at the reference position using a mechanical stop device, or by generating an electrical signal at the reference position using a micro-sinch, etc. There is a method in which the command is input to a microcomputer and the wavelength scanning motor is stopped based on the command from the microcomputer.

However, if the position of the mechanical stop device or microswitch mentioned above moves due to vibration or aging, the reference position of the wavelength scanning optical element will become inaccurate, and the reference wavelength will also change, causing measurement errors. This tends to cause problems. Conventionally, this has been corrected by adjusting the position of the mechanical stop device, microsinch, etc., but this adjustment method is extremely difficult and time consuming.

The present invention aims to improve the above-mentioned drawbacks of the prior art and provide a wavelength correction method for a spectrophotometer suitable for maintaining the wavelength accuracy of a spectrophotometer for a long period of time. A digital switch is connected to a computer, and the wavelength indication error obtained by measuring a known sample with a spectrophotometer is corrected by comparing it with a value that is half of the maximum setting value of the digital switch.

FIG. 1 is a block diagram showing a wavelength correction method of a spectrophotometer according to an embodiment of the present invention. Microcomputer 1
The wavelength scanning motor 20 is rotated by the 00 command, and the wavelength scanning optical element 30 is rotated by the wavelength scanning motor 20.
, for example, a diffraction grating or the like is rotated. At this time, when the reference position detection device 40, for example, a slider that moves in conjunction with a screw rod of a sine bar wavelength scanning mechanism, comes into contact with a microsinch installed at a predetermined position and operates, the signal a
is sent to the microcomputer 10 to automatically stop the wavelength scanning mechanism. That is, the rotation and stop of the wavelength scanning motor 20 is controlled by the microcomputer 10, and in the reference wavelength setting example ti, a digital switch 50 is connected to the microcomputer IO, and the reference wavelength is set as described above. At times, the microcomputer IO reads the set value of the digital switch 50. If the set value of the digital switch 50 is zero, the reference wavelength is set only by the signal a, and if the set value is not zero, the wavelength corresponding to this set value is set to the reference wavelength. The reference wavelength is corrected by addition and subtraction.

In practice, measurement is performed using a sample with an absorption line of a known wavelength or a light source with an emission line spectrum of a known wavelength, and if a wavelength setting error is found, the digital switch 50
By adjusting the wavelength and outputting an appropriate setting value, wavelength correction can be easily performed.

FIG. 2 is a 70-chart of the wavelength correction method shown in FIG. The microcomputer 10 rotates the wavelength scanning motor 20 to set the reference wavelength, and at this time reads the value of the digital switch 50 and compares it with M/2, which is half the maximum value M of the digital switch. If this comparison value C=M/2-D is zero, the microcomputer 1
0 determines that the reference wavelength is accurate. If the value of C is not zero, it is determined that the reference wavelength is inaccurate, and wavelength correction is performed to make C zero.

The operator measures a known sample and determines whether the wavelength is accurate or distorted. If the wavelength is accurate, the operator starts measuring the unknown sample without changing the wavelength. If the wavelength is inaccurate, the operator operates the digital switch 50 to correct the wavelength as described above. Let's do it) (Let the computer do it. In other words, wavelength correction is performed using a single child operation.

Note that the digital switch 50 can generally be set from zero to a positive value M. Therefore, in order to read positive and negative values with this digital switch 50, the microcomputer 10 must set the value M/2 to zero. If it is larger than M/2, it is positive, and if it is smaller, it is negative.

The wavelength correction method of this embodiment connects a digital switch to a microcomputer, first measures the indication error of a known wavelength of a known sample, and then operates the digital switch to easily correct the wavelength error. You can get the effect of

The wavelength correction method of the spectrophotometer of the present invention has the effect that the wavelength accuracy can be easily inspected and corrected, so that it can always be maintained in a good condition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a wavelength correction method for spectral light anomalies, which is an embodiment of the present invention, and FIG. 2 is a flowchart of the wavelength correction method shown in FIG.

Claims (1)

[Claims] 1. A microcomputer, a wavelength scanning motor controlled by the microcomputer, and a wavelength scanning optical element connected to the wavelength scanning motor;
In the wavelength scanning system of the spectrophotometer, which consists of a detection device that detects the reference position of the wavelength scanning optical element, a digital switch is connected to the microcomputer, and the wavelength determined by measuring a known sample with the spectrophotometer is used. A wavelength correction method for a spectrophotometer, characterized in that the indication error is corrected by comparing it with a value that is half the maximum setting value of the digital switch.