JPS6079248A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To make it possible to obtain accurate light measurement even if crosstalk and stray light are increased by reducing stray light, by preliminarily storing the degree of the influence of stray light or higher light between different wavelengths and calculating an actual influence amount from the multiplication result of the degree of the stored mutual influence and actually measured light intensity. CONSTITUTION:Light emitted from a light source 1 transmits a specimen 3 and is incident on a spectrometer 4. The output scanning pulse generator 8 and the output A/D converter 9 of a photodiode array 7 receives control by CPU10 and an electric signal amount E1 corresponding to each bit of the array 7 is stored in A-memory 11. On the other hand, proportion constants A1-An are stored in B-memory 12 corresponding to the arrangement of the bits of the array 7 and CPU10 takes out stored values E1, A1 corresponding to the same bit of the array 7 from the A-memory 11 and the B-memory 12 and E1 and A1 are multiplied in an operation part 3 which in turn further adds E1.A1+E2.A2+... +En. An. By this method, crosstalk due to the incompleteness of the spectrometer 4 can be removed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to yC luminous intensity reduction for the purpose of measuring the transmission or reflection of a sample, and is a method for eliminating the effects of stray light and higher-order light inherent in a spectrometer. Concerning the spectral luminosity side, which is the correct photometric value.

[Background of the invention]

Conventionally, in this type of spectrophotometry, in order to remove stray light and high-order light from diffraction gratings, unique ideas have been used, such as combining cant filters and adopting a double monochromator using two spectrometers. On the other hand, in recent years,
Multi-wavelength spectrophotometry using a multi-diode array has become popular, but a spectrometer using a multi-diode array cannot combine multiple cut filters in front of an 11-piece detection array, and it is difficult to use a double monochromator. It cannot be used either. Furthermore, in the case of a multi-diode array, there is also crosstalk to adjacent photodetectors of the detector itself, which causes the interrogation line to lack directness.

[Purpose of the invention]

The present invention is not limited to a spectrophotometer using a multi-diode array, but also has a function of automatically setting two or more wavelengths, and provides a spectrophotometer that can be affected by stray light and higher-order light. With the goal.

[Summary of the invention]

Physical optical removal methods are best for removing the effects of stray light and higher-order light, but optical removal methods may not be applicable in cases such as when using multiple diodes. Furthermore, even in a spectrophotometer equipped with an exit slit, there are cases in which it is desired to reduce stray light without using an optical removal method. In the present invention, the degree of influence of stray light and higher-order light between different wavelengths is stored in advance, and the actual amount of influence is calculated from the result of multiplying the stored degree of mutual influence by the actually measured light intensity. This is designed to reduce stray light and obtain correct photometric values.

[Embodiments of the invention]

First, the principle of the present invention will be explained. Now, spectrophotometry °
The wavelength range of the meter is divided into n points (n≧2), and the wavelengths of the husband and husband are λl, λ2, . Let λ3...A1...A0. On the other hand, when the light emitted from the light source of a spectrophotometer passes through the spectrometer and sample section and hits the detector, it is converted into an electrical signal amount proportional to the light intensity, but this electrical signal amount has a wavelength of λ
1. λ2...λ. It varies depending on the husband. Therefore, let this value be E11#E2...'°゛E. If the spectrometer was perfect, it would have two different wavelengths (λ1
．． There can be no mutual influence between E, , and EJO between λJ), but there may be a mutual influence jjAi in an actual spectrometer. This mutual influence is usually called stray light, higher order light, or crosstalk, and is determined by the structure of the spectrophotometer. Now, if we focus on the two wavelengths of 1 λh λ,
The electrical signal quantity EIK of the wavelength λ is the cross between the electrical signal tt[Et] that truly depends only on the wavelength λl and the signal El of the wavelength λj (including stray light and higher-order light), 02
Contains two ingredients. Since E', , is proportional to the electric signal amount E' of wavelength λJ, it can be expressed as E', lJ2AB-El. Here, A11 indicates the value at which the unit electric signal amount of wavelength J is mixed into the electric signal of wavelength i.

On the other hand, E+*EJ is an actual measurement result, and AIJ is a constant value unrelated to EIIEJ, which can be determined experimentally once the spectrophotometer system is determined.

Therefore, the true 'i' and the air signal ffi[E+] are expressed as follows.

(E I]=E + A I"・E,... Bright... (11 Up to now, we have considered two wavelengths, A1 and λj, but the total wavelength can be calculated using the following formula.

[EI] = EI-ΣA1, hat, river, group...
(2+-1 However, A-th = 0.

From the above analysis, A +i + A I21 A Is
・Memorize the song A In in advance by experiment, and then play the bs
e E2...If El is measured, (Et) is calculated from above.

This shows that the true photometric value E1 can be calculated even if the spectrometer is not perfect.

By the way, All r A12...Ala is a value indicating the degree of A4 of each wavelength with respect to wavelength λ1, but this value is determined by the wavelength λ fish, and if the wavelength λ1 changes, A 111 A +z・Yu・・A1.
, also changes.

Therefore, the wavelength λ1. For λ2...λ, respectively (A11l A12.Ate--A+n) (
A2t, A221A23...A2n)...
...(A, shiA.2...A,,), the total wavelength λ1...λ. The true photometric value (gt) [E2:]...[1].

] Gamaru. In this case, A11. A1□・・・・・・An
The number of memory points of a is the number of wavelength points n squared (I2).

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, the light emitted from the light source 1 is transmitted to the sample section 2 by 1α
After passing through the sample 3 , it enters the spectrometer 4 . The spectrometer 4 consists of an entrance slit 5, a concave diffraction grating 6 and a photodimate array 7. The output scanning pulse generator '8 of the photodiode array 7, the output A/L) converter 9 is controlled by the CPU10, and converts the electrical signals 1t, (H+) corresponding to each focus of the photodiode array 7 into A.
It is stored in the memory 11 bit by bit. This memory value is CP
It is cleared in synchronization with issuing a pulse generation command from Ul0 to the scanning pulse generator 8, and the latest photometric value is always stored.

On the other hand, the B memory 12 has proportional constants Al1A2, . . . corresponding to the bit arrangement of the photodiode array 7.
A is stored, and this value is always a constant value. A
When the memory 11 has finished storing all the electric signal amounts of the photodiode array 7, the CPU 10 takes the stored value E l'+ A + corresponding to the same bit of the photodiode array 7 from the A memory 11 and the B memory 12. Output calculation unit 1
Multiply E t + A I by 3. Furthermore, arithmetic unit 1
3 is El・AI +E2・n+...10E. -A
Add 1. However, A+=0. Next, the calculation unit 13 calculates E I' (Et-At+E2・Ax 1--+E,
- A-) and outputs the result to the output I10 circuit 14. The output I10 circuit 14 outputs the result to the display section 15.

From the above, crosses, etc. due to imperfections in the spectrometer 4 can be removed.

FIG. 2 is a block diagram showing another embodiment of the invention.

In FIG. 2, a photodiode array is not used as the spectrometer 4, and only light of a specific wavelength out of the monochromatic light produced by the concave diffraction grating 6 is output from the output slit 16.
The light enters the detector 17. The concave diffraction grating 6 is a rotating mechanism 18
Directly on top of tr.

Ru. The rotation mechanism 18 is driven by a wavelength drive motor 19 and a rotation mechanism section 18 . The wavelength drive motor 19 is driven by a wavelength drive circuit 20.

In FIG. 1, the side light value at each wavelength corresponds to the bit of the photodiode array 7, but in FIG. 2, it corresponds to the drive pulse of the wavelength drive motor. Unlike FIG. 1, in FIG. 2 the mechanical system scans all wavelengths, but the calculation processing after scanning is the same as in FIG. 1.

FIG. 3 is a block diagram showing still another embodiment of the present invention.

In Figure 1, the true dtll constant value (El
:], but in the embodiment shown in Fig. 3, in order to be able to measure all wavelengths, the OB memory 12 shown in Fig. 1 is multiplied by 8, and the memory Bss memory B2...Memo IJ B
fi. CPUl0 has an arbitrary wavelength λj
For the stored value E 1 'I'' E 2 of A memory 11
...... -El and the memory value of memory Bj12 1
+AB・・・・・・A fi4 is taken out and the true value [E,
], the results calculated over all wavelength points are displayed on the display section 15.
It is displayed and recorded on the recorder 21. As a result, the same effects as in the previous embodiment can be obtained.

In the above embodiment, the dispersion element of the spectrometer 4 was a concave diffraction grating, but it is obvious that a spectrometer using a plane diffraction grating or a prism spectrometer can also be used.

In addition, the number of memory points in the B memory 12 is the same as the number of memory points in the A memory 11, but the number of memory points is reduced to increase the memory capacity by 7.
If Z<L, a method of processing by interpolating the decreased amount using an interpolation method can also be easily implemented.

Furthermore, in the embodiment, the true photometric values are output and displayed as they are, but processing routines such as multiplication and logarithmic conversion can be inserted between the arithmetic unit 13 and the output I10 circuit 14 to output transmittance and absorbance. is also easy.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, correct photometry results can be obtained even when the optical characteristics of the spectrometer are insufficient and there are many cross beams or stray lights.

In particular, it is effective in eliminating the effects of stray light and crosstalk, which are the biggest drawbacks of spectrophotometers using multi-diode arrays.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the invention, FIG. 2 is a block diagram showing another embodiment of the invention, and FIG. 3 is a block diagram showing still another embodiment of the invention. 1...Light source, 2...Sample part, 3...Sample, 4...
・Spectroscope, 5... Input slit, 6... Concave diffraction grating, 7... Photodiode array, 8... Scanning pulse generator, 9... Output A/D converter, 10...・C
PU, 11...A memory, 12...B memory, 13
... Arithmetic unit, 14... Output I10 circuit, 15...
Display section, 16... Incidence slit, 17... Detector,
18... Rotation mechanism, 19... Wavelength drive motor, 20
... Wavelength drive circuit, 21... For recording. Agent Patent Attorney Akio Takahashi Figure 2!

Claims (1)

[Claims] 1. It has a light source, a spectral dispersion element, a sample part, and a detector, and the light emitted from the light source is converted into monochromatic light by an optical system including the dispersion element and is irradiated onto a monochromatic detector. In a spectrophotometer that measures the reflected light or transmitted light of a sample placed between the optical system, the light intensity of the monochromatic light that is irradiated onto the detector and converted into an electrical signal is measured with respect to at least two wavelengths. a first memory that stores the measured results for each wavelength; a second memory that stores a unique intensity ratio that does not vary depending on the photometric value corresponding to the wavelength array of the first memory; A spectrophotometric side characterized by comprising a multiplier and an adder/subtractor for extracting and multiplying data stored in a memory of the same wavelength with respect to the same wavelength. 2. The spectrophotometer according to claim 1, wherein the detector is constituted by a photodiode array. 3. The second memory corresponds to the wavelength array of the first memory,
2. The spectrophotometer according to claim 1, wherein a number of intensity ratios are stored as many times as the square of the number of wavelength arrays. 4. The spectrophotometer according to claim 1, wherein the unique intensity ratio stored in the second memory is a function of wavelength.