Optical system for sample processing instrument and sample processing instrument

An optical system for a sample processing instrument, wherein the sample processing instrument comprises a flow cell having a detection channel for passage and detection of a sample,

• the optical system comprising:
• a plurality of laser sources configured to emit light beams having different sizes at least in a first direction;
• a collimating device configured to collimate the light beams emitted from the plurality of laser sources;
• a focusing lens configured to focus the light beams coming from the plurality of laser sources on a point within the detection channel;
• and
• a reshaping device disposed between the collimating device and the focusing lens and configured to reshape a light spot of the collimated light beam,
• wherein the reshaping device comprises a first prism pair comprising two prisms, and the two prisms are adjustable relative to each other, so that all the light beams of the plurality of laser sources, after reshaping, have a same predetermined size in a first direction.