During the last few decades, photothermal radiometry(PTR) has been greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system employs an expensive lock-in amplifier to detect the weak photothermal signal, which leads to high cost and long test time. In this paper, a fast transmission PTR system based on sampling by using an internal computer sound card was developed to lower the system cost and shorter the test time. A piece of amorphous silicon(a:Si) thin film solar cells with artificial defects was prepared and tested by the system. The results show that the sharpened defects can be identified easily and quickly according to the significant peaks of the original infrared signal sampled by the internal computer sound card. Furthermore, more detailed defects can be investigated by processing the infrared signal. These validate the effectiveness of the proposed transmission PTR system as a low cost and efficient non-destructive test technique. However, the traditional PTR system has an greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system has an unusually locked-in amplifier to detect the weak photothermal signal, which leads to a high cost and long test time. In this paper, a fast transmission PTR system based on sampling by using an internal computer sound card was developed to lower the system cost and shorter the test time. A piece of amorphous silicon (a: Si) thin film solar cells with artificial defects prepared and tested by the system. The results show that the sharpened defects can be identified easily and quickly according to the significant peaks of the original infrared signal sampled by the internal computer sound card. investigated by processing the infrared signal. These validate the effectiveness of the proposed transmission PTR system as a low cost and efficient non-destructive test technique.