Digital-speckle-pattern interferometer (DSPI) is a wide-used technology in fined-measure. Nowadays common DSPI system employs high-power laser source and great experimental facilities, which is only suitable for lab research work. In order to extend its application into fieldwork, a new optical layout for portable DSPI meter is proposed in this paper, which is suited for low-power laser and has some advantages such as optimized compact framework and small size, Driven by a He-Ne laser of 5 mW output power, it shapes fine interferogram whose contrast is as well as that shaped by laser of 20 mW power. Thus utilization efficiency of laser is promoted. Based on the study in theory and experiments, the paper demonstrates rationality of the portable DSPI meter.