Abstract: A method for calibrating an instrument for using that instrument to obtain at least one light-related signal from particles under analysis comprises directing an incident beam of light at calibration particles having one or more known characteristics related to the particles expected to be analyzed. Both a light signal and a noise signal from the calibration particles are detected. A measurement is made of the ratio of the detected light signal to the detected noise signal, and that measurement is reported. The measured ratio is then compared to a predetermined ratio which represents a threshold for minimum instrument performance. This method further includes adjusting, if the predetermined ratio has not been attained, the operation of the instrument, while the calibration particles are within the incident beam of light, until the measured ratio reaches the predetermined ratio whereby the instrument is calibrated for subsequently obtaining the light signal from particles to be analyzed.

Abstract: A method for determining one or more characteristics of particles using multiple fluorescence analysis comprises directing an incident light beam at the particles under analysis. The particles include at least three fluorescent markers each having different emission spectra. The incident light beam causes the excitation of the markers by light at a single wavelength whereby different wavelengths of fluorescence are emitted from the particles. Different fluorescence emissions associated with the particles under analysis are simultaneously detected. This method further includes associating the detected fluorescence with one or more characteristics of the particles. An apparatus is also part of the present invention for carrying out the aforementioned method.

Abstract: A method for calibrating an instrument for using that instrument to obtain at least one light-related signal from particles under analysis comprises directing an incident beam of light at calibration particles having one or more known characteristics related to the particles expected to be analyzed. Both a light signal and a noise signal from the calibration particles are detected. A measurement is made of the ratio of the detected light signal to the detected noise signal, and that measurement is reported. The measured ratio is then compared to a predetermined ratio which represents a threshold for minimum instrument performance. This method further includes adjusting, if the predetermined ratio has not been attained, the operation of the instrument, while the calibration particles are within the incident beam of light, until the measured ratio reaches the predetermined ratio whereby the instrument is calibrated for subsequently obtaining the light signal from particles to be analyzed.