Abstract: A detection system and a portable detection device for detecting an object of interest in a lateral flow immunoassay strip. The lateral flow immunoassay strip has a detection carrier and a reporter, the detection carrier has a control zone and a test zone. The detection system has a laser light source, a scanning and spatial modulation module, a signal acquisition assembly, and a processing device. The laser light source provides a laser light. The scanning and spatial modulation module receives the laser light, and then provides a scanning and spatially modulating laser beam for irradiating a lateral flow immunoassay strip to generate a detecting signal. The signal acquisition assembly receives the detecting signal. The processing device electronic connects to the signal acquisition assembly and receives the detecting signal from the signal acquisition assembly.