JPH0213829A - Particle measuring apparatus - Google Patents

Abstract

PURPOSE:To calculate a correct diameter of a sample particle by arranging a non-linear optical member matched in phase with an irradiation light within an optical path of a photometry optical system. CONSTITUTION:A laser light with a wavelength lambda emitted from a laser light source 1 forms an image with a lens 8 at a position to be inspected at a passage section 3 within a flow cell 2. At the passage section 3, sample particles flow in sequentially one at a time and scattered light by the sample particles is condensed with a lens 4. A non-linear optical member 5 is matched in phase with an irradiation laser light, and if ever contacting the sample particles, part of the irradiation light passes through the non-linear optical member as intact with the wavelength lambda, undergoing no wavelength conversion. Here, light with the wavelength other than lambda/2 is cut off with a filter 6 and hence, light with the wavelength of lambda/2 alone is detected with a photo detector 7. Thus, a correct diameter of the sample particle can be determined from an output of the photo detector 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a particle measuring device, and in particular, to a particle measuring device that irradiates a laser beam or the like to test particles passing through a flow cell, and detects scattered light or fluorescence emitted from the test particles. This invention relates to a so-called flow cytometer that detects and analyzes the properties, structure, etc. of test particles.

[Prior Art] In conventional particle measuring devices, such as flow cytometers,
Irradiation light is irradiated onto a sample liquid such as blood cells that is wrapped in a sheath liquid and passes through a flow section having a minute rectangular cross section of, for example, 200 μm x 200 μm in the center of the flow cell, and the resulting forward scattered light and side scattered light are Particle measurements are performed by obtaining particle properties such as the shape, size, and refractive index of the target particles using light or even fluorescence.

FIG. 3 shows an example of a conventional particle analysis device. In the figure, test particles S pass through a flow section 3 in the center of a flow cell 2 perpendicular to the paper surface, and a laser light source 1 passes in a direction perpendicular to the flow. is located. Laser light emitted from this laser light source 1 is convergently irradiated onto the test particles S by an imaging lens system 8 made up of two cylindrical lenses orthogonal to each other.

Further, on the optical axis, a stopper 9, a condensing lens 4, and a photodetector 7 are arranged in this order on the opposite side of the laser light source 1 with respect to the particles S to be detected. The laser light emitted from the laser light source 1 is shaped into an imaging beam with arbitrary long and short diameters by an imaging lens system 8 made up of two cylindrical lenses orthogonal to each other. irradiated. The laser light traveling straight without being scattered by the test particles S is cut off by the stopper 9, and the forward scattered light among the scattered light scattered by the test particles S is focused on the photodetector 7 via the condenser lens 4. The forward scattered light intensity is measured. Further, the side scattered light and fluorescence are photometered by an optical system (not shown) provided in a direction orthogonal to the condenser lens 4.

Conventionally, it has been thought that the detected intensity of forward scattered light has a one-to-one correspondence with the particle diameter of the target particle, and the particle diameter has been calculated by a calculation circuit based on the detected intensity of forward scattered light.

[Problem that the invention seeks to solve] However,
In fact, in conventional methods that use monochromatic light such as laser light as the irradiation light, if the particles to be detected are translucent, the function of the detected scattered light intensity and particle diameter is monotonous, as shown in Figure 4. There is a problem in that the linearity does not become an increasing function and the linearity collapses around a certain particle size, making it impossible to calculate the accurate particle size around that area.

An object of the present invention is to provide a particle measuring device that can accurately determine the particle diameter of sample particles regardless of the particle diameter.

[Means for Solving the Problems] In order to solve the above problems, in a particle measuring apparatus that performs particle measurement by irradiating sample particles with irradiation light and measuring the generated scattered light with a photometric optical system, the above-mentioned method is used. A nonlinear optical member phase-matched to the irradiation light is disposed within the optical path of the photometric optical system.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention, in which a laser light source 1
A laser beam having a wavelength λ emitted from the flow cell 2 is imaged by a lens 8 at a test position in the flow section 3 in the flow cell 2 . Specimen particles flow into the flow section 3 one by one and pass through the test position, and the scattered light scattered by the specimen particles is focused by the lens 4. Of the irradiated laser light, the light that does not hit the sample particles is not scattered and travels straight along the optical path. Furthermore, when there are no specimen particles in the test area, naturally, no scattered light is generated and the irradiated laser light travels directly along the optical path.

A nonlinear optical member 5 is arranged behind the optical path of the lens 4,
Furthermore, a filter 6 and a photodetector 7 are arranged behind it. A nonlinear optical member is a member that has the property of emitting light that has been wavelength-converted with respect to incident light, and is particularly known for its SHG effect, which converts the wavelength λ of incident light to a half wavelength λ/2. In addition, at this time, it has the property of converting the wavelength of only the light that is phase-matched with the nonlinear optical member, and transmitting other light having a different phase with a significantly lower conversion efficiency with almost no wavelength conversion.

The nonlinear optical member 5 is phase-matched to the irradiated laser beam, and the phase of the light scattered by the sample particles or the light transmitted through the transparent sample particles is disturbed and the wavelength is not converted by the nonlinear optical member 5. become. That is, out of the irradiated light, the light that even slightly touches the sample particles is not wavelength converted by the nonlinear optical member and passes through the nonlinear optical member with the wavelength λ unchanged. Therefore, only the irradiated light that is not scattered or transmitted by the sample particles and passes through the portion other than the sample particles is wavelength-converted by the SHG effect of the nonlinear optical member and converted into light with a wavelength of λ/2. Here, the filter 6 cuts off the light with wavelengths other than λ/2, and the photodetector 7 detects only the light with the wavelength of λ/2.

As a result, it is thought that an inversely proportional relationship exists in which the larger the projected area of the analyte particles with respect to the irradiation light, the greater the amount of light blocked by the analyte particles, and the weaker the light detection intensity at the detected wavelength λ/2.

Therefore, assuming that the average specimen particle shape is spherical, the detected value and the particle diameter of the specimen particle have a l:1 relationship as shown in FIG. Using the relationship shown in FIG. 2, the photodetector 7
The accurate particle size of the sample particles can be determined from the output.

Note that the present invention is not limited to the above-mentioned flow cytometer, but is also applicable to latex immunodiagnosis devices and the like.

[Effects of the Invention] As described above, according to the present invention, a simple configuration in which a nonlinear optical member is disposed in the light receiving optical system of a particle measuring device exhibits a great effect in accurately calculating the particle diameter of sample particles.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 shows detection intensity and particle diameter in the embodiment. FIG. 3 is a diagram of the configuration of the conventional example, and FIG. 4 is a graph of the relationship between scattered light detection intensity and particle diameter in the conventional example. In the figure, 1... Laser light source, 2... Flow cell, 3... Flow section, 5... Nonlinear optical member, 6... Filter, 7
...photodetector

Claims (1)

[Claims] 1. In a particle measuring device that performs particle measurement by irradiating irradiation light onto test particles and measuring the generated scattered light with a photometric optical system, a particle that is phase-matched to the irradiated light is placed in the optical path of the photometric optical system. A particle measuring device characterized by disposing a nonlinear optical member.