JPH0612943U - Particle measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the density of the light intensity of the irradiation light to the sample fluid and to achieve cost reduction or downsizing of the device. [Arrangement] An irradiation optical system 7 for making irradiation light incident on an observation region R in the flow cell 1, and an optical system 15 for detecting scattered light generated by irradiation of fine particles in a sample fluid in the cell with the irradiation light are provided. The irradiation optical system 7 comprises a collimator lens optical system 10 for converting the light emitted from the light source 8 into parallel light, and a relay lens optical system 13 for further reducing the diameter of the parallel light, and the cell of the flow cell 1 The windows 2 and 3 are tilted with respect to the optical axis Q of the irradiation optical system, and a light blocking member 14 for blocking the return light from the cell window is provided in the vicinity of the condensing part P of the relay lens optical system. There is.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an apparatus for measuring fine particles contained in a fluid such as ultrapure water used for cleaning wafers in a semiconductor manufacturing process or clean air used in a clean room.

[0002]

[Prior art]

 As the above-mentioned fine particle measuring device, as shown in FIG. 4, a flow cell 23 having cell windows 21 and 22 of mutually parallel flat plates, an irradiation optical system 24 for making irradiation light incident on an observation region R in the cell 23, An optical system (not shown) for detecting scattered light generated by irradiating the fine particles in the sample fluid in the cell 23 with the irradiation light is provided, and the cell windows 21 and 22 of the flow cell 23 are connected to the irradiation optical system 24. The one tilted with respect to the optical axis Q is known. The irradiation optical system 24 is provided with a collimator lens 26 for collimating the light emitted from the light source 25 and an aperture c for transmitting the central portion of the parallel light having a Gaussian distribution, which has a strong cross-sectional intensity. And a light blocking member 27.

[0003]

[Problems to be solved by the device]

 In the fine particle measuring device having such a structure, it is currently the reason that the collimator lens 26 has a limit in reducing the diameter of the parallel light because the light shielding member 27 having the aperture c is provided to transmit the light in the central portion of the parallel light. This is because the cell windows 21 and 22 are required to have a small diameter even though the diameter cannot be reduced. On the other hand, inclining the cell windows 21 and 22 of the flow cell 23 with respect to the optical axis Q of the irradiation optical system 24 reduces the return light of the light reflected by the cell windows 21 and 22 to the light source 25 side, This is to reduce noise and improve the S / N ratio.

However, since the sample fluid is irradiated with only the light in the central portion of the parallel light, the light intensity becomes low and it is difficult to improve the S / N ratio. Further, in order to completely eliminate the influence of the returning light by inclining the cell windows 21 and 22 with respect to the optical axis Q of the irradiation optical system 24, the inclination angle of the cell windows 21 and 22 should be increased, or Either the low cell 23 should be installed far away from the irradiation optical system 24, and if the tilt angle is increased, the cell windows 21 and 22 of large area are required. There is a problem in that the device becomes large in size if the flow cell 23 is expensive or if the flow cell 23 is far away from the irradiation optical system 24.

The present invention has been made in view of such circumstances, and further improves the S / N ratio by increasing the density of the light intensity with which the sample fluid is irradiated. The objective is to provide a particle measurement device that enables the cell window to be downsized or the flow cell to be installed close to the light source.

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a particle measuring apparatus described at the beginning, wherein the irradiation optical system further includes a collimator lens optical system that converts light emitted from a light source into parallel light, and the parallel light. It is characterized in that it is composed of a relay lens optical system for reducing the diameter, and a light blocking member for blocking the return light from the cell window is provided in the vicinity of the condensing part of the relay lens optical system.

[0006]

[Action]

 According to the above characteristic configuration, it is possible to reduce the diameter of the cell window by further reducing the diameter of the irradiation light that is collimated by the collimator lens optical system, and at the same time increase the density of the irradiation light intensity for the sample fluid. Is achieved. In addition, since a light blocking member is provided near the condensing part in the relay lens optical system that is necessary for further reducing the diameter of the parallel light, it is possible to irradiate the light returning from the cell window to this light blocking member. In other words, by slightly tilting the cell window with respect to the optical axis of the irradiation optical system so that the return light is slightly removed from the condensing part, the light reflected by the cell window is returned to the light source side. This can surely be prevented, and eventually, the cell window can be downsized or the flow cell can be installed close to the light source.

[0007]

Embodiment An embodiment of the present invention will be described below with reference to the drawings. Figures 1 and 2 show the principle of the particle measuring device. Reference numeral 1 is a flow cell equipped with parallel flat cell windows 2 and 3, and the cell windows 2 and 3 are provided on the side in the direction orthogonal to the facing direction. A scattered light detection window 4 is provided. Reference numeral 5 is a sample fluid inlet formed in the lower portion of the flow cell 1, and 6 is a sample fluid outlet formed in the upper portion of the flow cell 1. Reference numeral 7 denotes an irradiation optical system that makes irradiation light incident on an observation region R in the flow cell 1, and includes, for example, a light source 8 made of a semiconductor laser, and collimator lens optics for collimating the light emitted from this light source 8 by a collimator lens 9. It is composed of a system 10 and a relay lens optical system 13 which further reduces the diameter of the parallel light by two relay lenses 11 and 12.

In the vicinity of the condensing part P formed by the two relay lenses 11 and 12 of the irradiation optical system 7, a light shielding member 14 having an aperture a for transmitting the condensed irradiation light is provided. The cell windows 2 and 3 of the flow cell 1 are tilted, for example, slightly downward with respect to the optical axis Q of the irradiation optical system 7 so that the light shielding member 14 is irradiated with the return light from the cell windows 2 and 3. I am trying. Reference numeral 15 denotes a detection optical system provided outside the flow cell 1 opposite to the scattered light detection window 4, and includes a condenser lens 16 for condensing scattered light generated from fine particles of the sample fluid, and a light detection for detecting scattered light. It consists of vessel 17 and.

In the fine particle measuring device having the above-described configuration, the sample fluid is introduced into the observation region R in the flow cell 1 through the inlet 5, the collimator lens optical system 10 collimates the parallel light, and the relay lens optical system 13 further reduces the diameter. The laser light thus generated is directed toward the sample fluid flowing through the observation region R. At this time, if the sample fluid contains fine particles, the light scattered by the fine particles is collected by the condenser lens 16. The light is emitted and detected by the photodetector 17, and the number of fine particles is counted and the particle size distribution is measured based on the output signal from the photodetector 17.

Then, the return light when the further reduced parallel light is reflected by the cell windows 2 and 3 is radiated to the light shielding member 14 provided in the vicinity of the condensing portion P of the relay lens optical system 13 to shield the light. However, since the return light is surely prevented from returning to the light source 8 side, the S / N ratio is improved. Become. In order to prevent the return light from irradiating the light source 8 side by irradiating the light shielding member 14 with the return light, the cell windows 2 and 3 are slightly moved with respect to the optical axis Q of the irradiation optical system 7. Since it is only necessary to incline, it is possible to reduce the diameters of the cell windows 2 and 3 and to install the flow cell 1 close to the light source 8 as is apparent from FIGS. Alternatively, if only the gentle inclination of the cell windows 2 and 3 is selected, it is possible to install the flow cell 1 close to the condenser lens 10 and thus to downsize the device. It is also possible to take an eclectic form in which the diameters of the cell windows 2 and 3 are reduced and the device is downsized by moderately sloping.

In the embodiment, the aperture a is formed in the light shielding member 14 so that the irradiation light focused on the aperture a is transmitted. However, as shown in FIG. The light-shielding member 14 is provided on the side of the optical axis Q of the system 7 in the direction of inclination of the flow cell 1, and the light-shielding edge b of the light-shielding member 14 is positioned so as to be close to the light converging portion P. It is possible to implement the mode in which the return light from the cell windows 2 and 3 is shielded in the vicinity of the light section P.

[0012]

[Effect of device]

 As described above, the present invention can reduce the diameter of the cell window of the flow cell by collimating the light emitted from the light source and further reducing the diameter of the collimated light. At the same time, it is possible to increase the density of the light intensity of the irradiation light on the sample fluid. Moreover, since the light condensing part of the relay lens optical system that further reduces the diameter of the parallel light is specified and the light shielding member is provided in the vicinity of this light condensing part, the cell window is set as the optical axis of the irradiation optical system. On the other hand, it is possible to surely prevent the return light from the cell window from returning to the light source side simply by tilting the cell window. This makes it possible to improve the S / N ratio by reducing the light source noise and to reduce the cell window It became possible to reduce the diameter by sloping or to install the flow cell close to the light source, which eventually led to cost reduction and downsizing of the device.

[Brief description of drawings]

FIG. 1 is a principle plan view of a particle measuring device.

FIG. 2 is a side view showing the principle of a particle measuring device.

FIG. 3 is an explanatory diagram showing a light shielding form of another embodiment.

FIG. 4 is a principle side view of a conventional particle measuring device.

[Explanation of symbols]

1 ... Flow cell, 2, 3 ... Cell window, 7 ... Irradiation optical system, 8
... light source, 10 ... collimator lens optical system, 13 ... relay lens optical system, 14 ... light blocking member, 15 ... detection optical system, P ... condensing part, Q ... optical axis, R ... observation area.

Claims (1)

[Scope of utility model registration request] 1. A flow cell having a parallel-plate cell window, an irradiation optical system for making irradiation light incident on an observation region in the cell, and the irradiation light being generated by irradiation of fine particles in a sample fluid in the cell. With an optical system for detecting scattered light,
In a fine particle measuring apparatus in which a cell window of the flow cell is tilted with respect to an optical axis of an irradiation optical system, the irradiation optical system includes a collimator lens optical system that converts light emitted from a light source into parallel light, and the parallel light. And a relay lens optical system for further reducing the diameter, and a light blocking member for blocking the return light from the cell window is provided in the vicinity of the condensing part of the relay lens optical system. Particle measuring device.