提出一种长波红外光谱的温度场测量方法。 将谱色测温原理与三级Fabry-Perot(FP)型Liquid Crystal Tunable Filter(LCTF)相结合， 并对测温理论模型中三组非线性相关方程组所得的解进行了优化， 以进一步减小误差， 使测量值更加客观、 真实； 然后运用液晶双折射可调谐滤光原理， 制作了三级FP型LCTF滤光系统， 该系统在一定的长波红外光谱范围内实现了波长的任意调谐， 从而保证测温系统的响应快速、 准确。 该方法测温前无需知晓被测物发射率， 且能有效抑制背景光辐射和环境光源对测温精度带来的影响， 保证了测温结果的准确性。 最后通过matlab仿真软件验证了滤光系统所得红外光谱符合系统设计要求， 并通过实验验证了该测温方法的可行性， 测温准确性较之传统的单波段红外热像仪得到了提高。

A temperature field detection method based on long-wavelength infrared spectrum for hot forging is proposed in the present paper. This method combines primary spectrum pyrometry and three-stage FP-cavity LCTF. By optimizing the solutions of three group nonlinear equations in the mathematical model of temperature detection, the errors are reduced, thus measuring results will be more objective and accurate.Then the system of three-stage FP-cavity LCTF was designed on the principle of crystal birefringence. The system realized rapid selection of any wavelength in a certain wavelength range. It makes the response of the temperature measuring system rapid and accurate. As a result, without the emissivity of hot forging, the method can acquire exact information of temperature field and effectively suppress the background light radiation around the hot forging and ambient light that impact the temperature detection accuracy. Finally, the results of MATLAB showed that the infrared spectroscopy through the three-stage FP-cavity LCTF could meet the requirements of design. And experiments verified the feasibility of temperature measuring method. Compared with traditional single-band thermal infrared imager, the accuracy of measuring result was improved.