Liquid level detection device that irradiates a container at multiple angles

A liquid level detection device comprising:

• an irradiation unit configured to irradiate a side surface of a sample container containing a sample having layers with light;
• a light receiving unit configured to receive transmitted light that is the light emitted from the irradiation unit and passing through the sample container;
• an analysis unit configured to acquire an interface between the layers of the sample contained in the sample container based on received amounts of the transmitted light received by the light receiving unit;
• a first drive unit configured to move the sample container in a vertical direction relative to the irradiation unit and the light receiving unit;
• a second drive unit configured to move the sample container in a circumferential direction of the sample container relative to the irradiation unit and the light receiving unit;
• and
• a control unit configured to control the first drive unit and the second drive unit,
• wherein the control unit controls the second drive unit, so that the irradiation unit irradiates the sample container with the light at a first irradiation angle and a second irradiation angle different from the first irradiation angle, and the light receiving unit receives transmitted light that is the light passing through the sample container,
• wherein the analysis unit acquires an interface between the layers of the sample based on received amounts of transmitted light at the first irradiation angle and the second irradiation angle by using an analysis method selected based on at least one of a type of a separator forming a layer in the container or presence or absence of the separator,
• wherein the separator includes a first separator having a small change in received amounts of transmitted light at the first irradiation angle and the second irradiation angle, and a second separator having a large change in received amounts of transmitted light at the first irradiation angle and the second irradiation angle,
• wherein when the separator is the first separator, the analysis unit acquires the interfaces at the first irradiation angle and the second irradiation angle based on a change in received amounts of the transmitted light in the vertical direction at the first irradiation angle and the second irradiation angle, compares the acquired interfaces at the first irradiation angle and the second irradiation angle, and acquires a highest position or a lowest position of the interface, and
• wherein when the separator is the second separator, the analysis unit compares changes in received amounts of the transmitted light in the vertical direction at the first irradiation angle and the second irradiation angle, and acquires the interface based on measurement data with a largest change in the received amounts of the transmitted light.