为改进红外锁相热成像检测中的热调制激励效果，提高系统集成和使用性能，引入了数字功率控制技术。以可控硅为功率元件，推导控制角与功率的关系。以正弦调制激励为例，通过数值计算求解控制角随时间的变化规律，基于数字电路设计导通角控制算法和实现方法建立了实验平台并进行了实验验证和对比。结果表明：该方法的功率控制精度高，热成像波形的保真度明显优于常规激励技术，体积和结构也得到改善，电磁安全性满足要求，可以更好地应用于红外锁相热成像检测中。

To improve the integration level and performance of modulated heat excitation source, a new digital power control technology was developed for application of lock-in thermography in NDT. Silicon controlled rectifier(SiCR) was used as a power output controlling unit, and a relationship between SiCR′s control angle and output power was also obtained. Taking the sinusoidal signal as the excitation source, the changing rule of control angle over time was achieved by using numerical calculation while the control algorithm and implementation method of the conduction angle were designed based on digital micro processing circuit. The experimental platform was thus built up and the comparison experiments were carried out. The results show that the present approach can gain higher precision of power control, better fidelity of thermal waveform and preferable equipment in structure and size. Moreover, its electromagnetic safety can meet the relevant requirement. Therefore, better results can be expected by using this method in the infrared lock-in thermography.