OPTICAL DETECTOR FOR FLOWING
SAMPLE AND OPTICAL DETECTION
METHOD FOR FLOWING SAMPLE
BACKGROUND OF THE INVENTION 5
1. Field of the Invention
The present invention relates to an optical detector for flowing sample and an optical detection method for flowing sample.
2. Description of the Related Art 10 In a general prior art for analyzing a sample an optical
detector for flowing sample is frequently used. The optical detector for flowing sample irradiated a light from a light source to the sample made to flow in a light transmitting flow path before detecting the light having passed the sample. The sample then is analyzed on the basis of results of the detection.
La the prior art for leading a light from a light source to a light transmitting flow path, a slit is arranged before the 20 light transmitting flow path, the light from the light source is converged at the slit before coming in the light transmitting flow path, and after that the light is irradiated to the sample.
As the light is converged before the light transmitting flow 25 path in that way, the light is minimized in the cross-sectional area when it passes the slit before passing the light transmitting flow path while being diverging. The prior art is disadvantageous in that parts or all of the light beam are reflected or absorbed by the inside walls of the light trans- 30 mitting flow path or the slit.
Another known prior art has a light transmitting flow path formed so as to track along a diverging light beam. The prior art can solve the disadvantage that the light beam is reflected or absorbed by the inside walls of the light transmitting flow 35 path. However, the prior art cannot prevent the light beam from being reflected or absorbed by the slit still. The prior art also has such a disadvantage that since diameter of the flow path is different at positions, the density distribution of the liquid pressure is dispersed. This results in deviation of 40 the track of the light beam.
In view of the foregoing, it is an object of the present invention to provide an optical detector and detection method for flowing sample that can solve the problems of difficulties in the light path. 45
SUMMARY OF THE INVENTION
Briefly, the foregoing object is accomplished in accordance with aspects of the present invention by the construction that a light from a light source is converged in a light 50 transmitting flow path.
Preferably, the optical detector for flowing sample comprises a light source, a spectroscope for separating a light emitted from the light source, a detector for detecting a light led out of the spectroscope, a light transmitting flow path 55 (flow cell) positioned in a light path between the detector and the spectroscope, wherein at least a slit and a light condenser for condensing a dispersed light having passed the slit are arranged in that order between the spectroscope and the flow cell in the light path. 60
Further preferably, the optical detector for flowing sample provides the feature that the light transmitting flow path (flow cell) is positioned so that a direction of the light path coincides with a sample flowing direction of the flow cell and the flow cell and the light condenser are arranged so that 65 a focus of the light condenser is positioned at a center of or near the center of a sample flow path of the flow cell.
Depending on situation, the flow cell or the light condenser is arranged so that the focus of the light condenser is positioned at an end of or near the end of the flow cell in the light path direction.
Further, a light beam splitter is arranged in the course of convergence of the light condenser to split the light beam to the sample side and reference side.
Since the optical detector for flowing sample is constructed as described above, the light beam can enter the light transmitting flow path as being converged and can be focused in the light transmitting flow path.
Since the focus is put within the light transmitting flow path, little light beam is cut by the inside walls even if the light beam passes over the focus position and diverges.
Since the light condenser can have the focus at a desired position in the sample flow path as described in the preferable construction, the optical system can be set depending on cause of measurement error. As an example, the focus should be ordinarily put at the center of the sample flow path to which most of the light beam enters the light transmitting flow path (flow cell). If the optical axis in the flow cell is changed too much by density change of the liquid flowing in the flow cell, the focus should be set to the sample-side detector.
The light beam splitter for splitting the light beam can be arranged on the sample and reference sides in the course of convergence of the light converging means to feed the light beam of virtually the same condition to the both detectors.
The present invention has the sample-side and object-side optical systems arranged to have as the same conditions as possible to make delicate optical axis adjustment unnecessary. The present invention also allows easy corrections of change of the light source position by the object-side signal, slight deviation of the optical axis, and other changes that have been ordinarily difficult to correct.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an outline illustrating an embodiment according to the present invention;
FIG. 2 is a cross-sectioned view illustrating an example of relationship between a position of convergence of light beam and that of the flow cell used in the embodiment of FIG. 1;
FIG. 3 is a cross-sectioned view illustrating another example of relationship between a position of convergence of light beam and that of the flow cell used in the embodiment of FIG. 1; and
FIG. 4 is a view illustrating a different example and its effect
DETAILED DESCRIPTION OF THE
The following describes in detail an embodiment according to the present invention by reference to the accompanying drawings.
FIG. 1 depicts an outline illustrating an optical system of the optical detector for flow sample according to the present invention. The detector of the embodiment comprises a light source chamber 1, a spectroscope chamber 2, and a detector chamber 40. A light is emitted by a deuterium lamp 3. The emitted light is condensed by a light condensing mirror 4. The condensed light enters the spectroscope chamber 2 from a quartz window 5. The light then enters the spectroscope from a light incoming slit 7 through a cut filter 6. The light