Patent ID: 8269952

Claim:
A sample analyzer, comprising: an input device that is used to select a measurement mode corresponding to an analyzed component of a biological sample; a measurement sample preparation section that comprises at least an aspirating pipette configured to aspirate the biological sample and a chamber configured to receive the biological sample aspirated by the aspirating pipette and a reagent, wherein a measurement sample for analysis under the selected measurement mode is prepared from the biological sample and the reagent received in the chamber; a flow cell configured to flow the measurement sample therethrough; a laser diode configured to irradiate the measurement sample flowing through the flow cell with laser light; a light receiving part configured to receive light from the irradiated measurement sample and to generate electrical signals; a signal processing circuitry configured to process the electrical signals generated by the light receiving part; an analysis section configured to analyze the component of the biological sample based on an output from the signal processing circuitry in such a manner peculiar to the selected measurement mode; a light amount detector configured to detect an amount of light emitted from the laser diode; a direct current output part for configured to output a direct current to be supplied to the laser diode; a light amount setting part for changing the amount of light emitted from the laser diode according to an analyzed component of the sample by changing the magnitude of the direct current output from the direct current output part, wherein the direct current output part outputs the direct current to be supplied to the laser diode such that the amount of light emitted from the laser diode is maintained at the amount changed by the light amount setting part, based on the amount of light detected by the light amount detector; a high frequency superimposing part configured to superimpose a high frequency component on the direct current output from the direct current output part; and a high frequency control part configured to control amplitude of the high frequency component output from the high frequency superimposing part according to the magnitude of the direct current output from the direct current output part such that the laser diode oscillates in a multi-mode.