JPH05126726A - Analysis optical system for centrifugal separation device - Google Patents

Abstract

PURPOSE:To enable an optical phase distribution of a sample to be measured speedily and highly accurately by detecting a phase difference between differential frequency signal components with two frequencies of laser beam which is transmitted through a reference sample and a measurement sample. CONSTITUTION:Zeeman-type He-Ne laser 15 irradiates a laser beam with different frequencies f1 and f2 with a differential frequency being DELTAf. The laser beam is divided 16, one beam is detected 18 through a polarizer 17, and then a detection signal Ir with a period 1/DELTAf is used as a reference signal. On the other hand, the transmitted laser beam 16 passes through a mirror 20, a lens 19, and a vacuum container window 7 and irradiate a reference sample 11 and a measurement sample 10 within a cell 2 of the rotary rotor 1 with a constricted fine spot. The transmission light is detected by a detector 18 through mirrors 4 and 5, a vacuum container window 8, a polarizer 23 etc. A time difference T2-T1 of a signal waveform is measured from a phase relationship of a signal waveform of a reference signal signal 29, a reference sample signal 30, and a measurement sample signal 31 where a signal Ir and detection signals Ib and Is of the samples 11 and 10 are expressed by each specific expression, thus enabling an optical phase distribution of the sample 10 to be calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention holds a sample on a rotor,
In a centrifuge device that separates substances of different mass in a sample by centrifugal force generated by rotating a rotor, an optical device for analyzing a substance in a sample during rotation, particularly absorption of a wavelength of light to be measured. The present invention relates to an optical device for analyzing a nonexistent sample.

[0002]

2. Description of the Related Art An analysis optical system of a conventional centrifuge will be described with reference to FIGS. Reference numeral 1 in FIG. 2 shows a rotor 1 housed in a vacuum container 12. The cells 2 are arranged on the circumference of the rotor 1. As shown in FIG. 3, a reference sample 11 and a measurement sample 10 are arranged side by side in the cell 2.
The rotor rotates as indicated by the arrow 3, and the sample in the cell is subjected to centrifugal separation in the rotor radial direction (indicated by the arrow 13) to separate the components in the sample. When the sample component does not absorb the light to be measured, the sample component is analyzed by measuring the refractive index distribution. The light 6 from the mercury lamp is the vacuum container window 7
To illuminate the cells in the rotor. The light passing through the cell is reflected by the mirrors 4 and 5, and is taken out from the vacuum container window 8. FIG. 4 schematically shows a method of forming interference fringes from the light 9 extracted to the outside. Reference sample 1
The light 9 that has passed through 1 and the measurement sample 10 causes an interference fringe to be generated at a position 14 by the prism 32. FIG. 5 shows an example of interference fringes in the rotor radial direction of the sample. It can be seen that the straight lines of the interference fringes are distorted. By analyzing this distortion, the refractive index distribution generated by the separation of the measurement sample by the centrifugal force, that is, the optical phase distribution can be measured as a relative one with respect to the reference sample. However, conventionally, in order to analyze this interference fringe, the interference fringe is photographed, and then the interference fringe is read and analyzed. This way once
It takes a lot of time since the photograph is taken, and the accuracy of reading the interference fringes is limited to about 1/10 of the interference fringe pitch.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and is to enable the optical phase distribution of a sample to be measured at high speed and with high accuracy.

[0004]

In the device of the present invention, the reference sample and the measurement sample arranged in the rotor are sequentially irradiated with laser light having two frequencies (f ₁ and f ₂ ) by rotation. As described above, the difference frequency signal components having the respective f ₁ -f ₂ frequencies of the light transmitted through the reference sample and the measurement sample are taken out, and the optical phase distribution of the measurement sample is detected by detecting the phase difference between them. It is characterized by doing.

Of the laser beams having two frequencies (f ₁ and f ₂ ), the laser beams having the frequencies f ₁ and f ₂ are simultaneously applied to the reference sample and the measurement sample respectively placed in the rotor. Irradiation and transmission are performed, the transmitted light is interfered, and the difference frequency signal component having the f ₁ -f ₂ frequency of the interference light is extracted, and the phase difference from the signal phase before the laser light is applied to the rotor is determined. The detection method can also detect the optical phase distribution of the measurement sample.

[0006]

EXAMPLE FIG. 1 shows an analytical optical system for centrifugation according to the present invention. In this optical system, He-Ne utilizing Zeeman effect
It uses a laser. From this laser, laser light beams of different frequencies whose polarization directions are orthogonal to each other are emitted. The frequencies are f ₁ and f ₂ , and the difference frequency f ₁ −f ₂ is Δf. Δf
Can be set to about 8 MHz. The laser light emitted from the laser is split into two by the beam splitter 16. One of the beams passes through the polarizer 17 and the photodetector 1
Detected at 8. FIG. 6 shows the relationship between the polarization direction of laser light and the direction of the polarizer. The laser light is polarized in the x and y directions. The orientation of the polarizers is set at 45 ° with respect to them. The amplitude of light polarized in the x direction can be expressed as Ax = Aexp (2πif ₁ t) (1) The amplitude of light polarized in the y direction can be expressed as Ay = Aexp (2πif ₂ t) (2) . It passes through the polarizer 28 and the photodetector 1
The signal Ir detected at 8 is proportional to the following equation.

Ir = | Ax / √2 + Ay / √2 | ² = A ² (1 + cos (2πΔft)) (3) This signal waveform has a period 1 as shown by 29 in FIG.
The signal of / Δf is named as a reference signal. On the other hand, the laser light transmitted through the beam splitter is reflected by the mirror 20 and the lens 1.
9. Passing through the vacuum vessel window 7, the sample in the cell has a diameter of 0.1.
It is narrowed down by a minute spot of about mm. The reference sample and the measurement sample in the cell are sequentially irradiated with laser light because the rotor 1 is rotating. The transmitted laser light passes through the mirrors 4 and 5, the vacuum container window 8, the polarizer 23, and the lens 24, and is detected by the photodetector 18. Further, the mirror 20 and the unit 21 of the lens 19 move integrally as shown by an arrow 22, so that the optical characteristic distribution of the sample in the rotor radial direction can be measured. The polarizer 23 is the same as that described above, and is set at an angle of 45 ° with the polarization directions x and y of the laser light as shown in FIG. When the rotor rotates and the laser light passes through the reference sample, the photodetector 18
Ib = B ² (1 + cos (2πΔf (t−T ₁ ))), where Isb is the signal detected when the laser light passes through the measurement sample. ² (1 + cos (2πΔf (t−T ₂ ))) (5). FIG. 7 shows the phase relationship of the signal waveforms of the reference signal 29, the reference sample signal 30, and the measurement sample signal 31 shown in Expressions (3), (4), and (5). Time difference of the signal waveform, it is possible to calculate the optical phase distribution of the measurement sample by measuring T ₂ -T _1. For example, when the thickness of the sample is d, the refractive index of the reference sample is n, and the refractive index of the measurement sample is n + Δn, the optical phase difference φ between the laser light transmitted through the reference sample and the measurement sample is represented by the following equation.

Φ = (2π / λ) Δnd (6) The optical phase difference and the signal waveform have the following relationship.

Φ = 2πΔf (T ₂ −T ₁ ) (7) From Equations (6) and (7), Δn can be calculated as Δn = (T ₂ −T ₁ ) Δf (λ / d) (8) . The time difference, T ₂ −T _1, is 1 of 1 cycle 1 / Δf
/ 100 can be measured. If the time difference is measured with this accuracy, the sample thickness d = 15 mm, wavelength λ = 0.632
If it is 8 μm, Δn can be measured with high accuracy of 4.2 × 10 to ⁷ . FIG. 8 shows an example of measuring the optical characteristics of the measurement sample in the rotor radial direction. FIG. 6A is an example in which the distribution of the time difference is measured in the rotor radial direction. The time difference is proportional to the optical phase difference as shown in the equation (7).
The figure (b) is what differentiated the figure (a). A region in which the rate of change of the components in the centrifugally separated measurement sample is high can be highlighted. The sample is contained in a container as shown in FIG. Quartz glass is used for the light transmitting region of this container, that is, the container window. In the present invention, the optical phase of the sample is measured, but at the same time, the optical phase of the container window is included in the measurement. To solve this problem, when the sample is set on the rotor and the rotation speed of the rotor is slow and the sample to be measured has not been centrifuged yet, the optical phase difference is measured as the initial state and the rotation speed of the rotor is measured. Goes up,
If the sample is centrifuged after a sufficient time, or if the optical phase difference is measured again and the measured value in the initial state is subtracted from this measured value, it is possible to measure the sample that is not affected by the container window. become.

[0010]

As described above, the analytical optical system for a centrifuge of the present invention shown in FIG. 1 makes it possible to measure the optical phase distribution of a measurement sample during centrifugation with high accuracy and in a short time. , It becomes possible to analyze the components in the measurement sample with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an analysis optical system for a centrifuge of the present invention.

FIG. 2 is a schematic diagram showing a conventional analysis optical system for a centrifuge.

FIG. 3 is a plan view showing a cell including a reference sample and a measurement sample.

FIG. 4 is a schematic diagram showing the operation of a conventional analysis optical system for a centrifuge.

FIG. 5 is a schematic diagram showing the operation of a conventional analysis optical system for a centrifuge.

FIG. 6 is a graph showing a polarization direction of laser light and a set angle of a polarizer.

FIG. 7 is a waveform diagram showing a signal waveform.

FIG. 8 is a waveform diagram showing an example of measuring an optical phase distribution of a measurement sample in a rotor radial direction.

[Explanation of symbols]

Reference numeral 1 is a rotor, 2 is a cell, 4 and 5 are mirrors, 7 and 8 are vacuum vessel windows, 10 is a measurement sample, 11 is a reference sample, 12 is a vacuum vessel, and 15 is a Zemann type He-Ne laser. The beam splitter 16, 16 a beam splitter, 17 and 23 a polarizer, 19 and 24 a lens, 20 a mirror, 18 a photodetector, 25 a circuit device, and 26 and 27 a laser light polarization Direction, 28 is the direction of the polarizer, 29 is the reference signal, 30 is the signal from the reference sample,
Reference numeral 31 is a signal from the measurement sample, and 32 is a prism.

Claims (1)

[Claims] 1. In an optical device for transmitting light to a sample held in a rotor to detect an optical phase distribution generated in the sample, a reference sample and a measurement sample arranged in the rotor are sequentially rotated by rotation. It is irradiated with laser light having two frequencies, and the difference frequency signal components having two frequencies of the light transmitted through the reference sample and the measurement sample are extracted, and the phase difference between them is detected to detect the measurement sample. Analytical optical system for centrifuge that detects optical phase distribution.