2004 Volume 14 Issue 2 Pages 33-37
A flow cytometer is used for rapid analyses of cells or chromosomes. For an optical system of flow cytometer, it is important to adjust the center of illuminating laser beam to a jet-stream. Microspheres or leukocytes are used for focus adjustment. Adjusted best position is the location where fluorescence of standard samples becomes the brightest. Manual adjustment of the optical-axis is not only complicated but also inaccurate. A slit-scan flow cytometer measures the morphological information along the objects being analyzed. The laser beam size of our instrument at the tightly focused position has dimensions of 0.95 in the flow direction by 85.0 across with a depth of focus being only 1. At unfocused position, width of the slit becomes wider and intensity of the peak beam becomes weaker. To guarantee best focusing, we examined a method of opticalaxis adjustment for the slit-scan flow cytometer by controlling position of the jet-stream based on fluorescence intensities of microspheres passed. The computer controlled optical adjustment system ensures stable and reliable measurements by the slit-scan flow cytometer.
