空间频域成像（Spatial Frequency Domain Imaging，SFDI）技术凭借非接触、宽视场的优势，已被广泛应用于水果品质检测领域。然而，传统多光谱SFDI系统仍存在透射效率低、光谱范围受限、依赖机械扫描等问题。为克服上述缺陷，本研究研发了一款波长在450~1040 nm范围内连续可调的SFDI系统，该系统通过图案化单色光照明，可实现连续光谱成像与选段波段成像。系统采用模块化设计，集成了单色光生成模块、投影模块、成像模块和电动成像平台，这种结构设计支持光源与投影模块的灵活耦合和更换，能够根据实际应用需求，对不同波长范围的光学特性参数（Optical Properties，OPs）进行自动化测量。该系统具备高可调性，可通过专用采集软件实现特定波长的定制化测量；同时，仅需升级光源和红外敏感投影模块，即可将光谱范围拓展至更长的红外波段，具备良好的拓展潜力。借助波长可调的特性，本研究通过联合调控空间频率与波长，验证了该系统实现深度分辨成像的能力，实验结果表明，该系统的成像深度可达3~4 mm。利用本系统测得的多种水果光学OPs与积分球法提供的参考值高度吻合，其中吸收系数（ ）的平均测量误差约为0.002 mm−1，约化散射系数（ ）的平均测量误差约为0.02 mm−1。在桃子硬度预测的应用实例中，基于该系统构建的预测模型，其预测决定系数（ ）达到0.786。上述结果表明，本系统的测量精度优于现有多波长SFDI设备，这一提升得益于系统拓展的光谱范围能够获取更丰富的果实组织信息，凸显了其在水果品质评价中的应用潜力。更为重要的是，本研究实现了SFDI设备从固定多光谱传感向定制化、连续波段成像的转变，为SFDI仪器的研发建立了新范式，拓宽了其在农产品无损检测乃至其他生物组织检测领域的应用范围。

Spatial frequency domain imaging (SFDI) has been widely applied in fruit quality inspection because of its noncontact and wide-field advantages. However, conventional multispectral SFDI systems remain constrained by low transmission efficiency, limited spectral range, and reliance on mechanical scanning. To overcome these limitations, we developed a continuously tunable wavelength SFDI system (450-1040 nm) that enables both continuous-spectrum and selectable-band imaging through patterned monochromatic illumination. The system adopts a modular design that integrates a monochromatic light generation module, a projection module, an imaging module, and a motorized imaging platform. This configuration allows flexible coupling and replacement of light sources and projection modules, enabling automated measurement of optical properties across different wavelength ranges according to application needs. With its high tunability, the system supports customized measurements at specific wavelengths via dedicated acquisition software, and it also provides the potential for spectral extension into longer infrared bands by simply upgrading the light source and infrared-sensitive projection module. Leveraging its wavelength tunability, we further demonstrated the system’s capability for depth-resolved imaging by jointly regulating the spatial frequency and wavelength. The results showed that the system achieved an imaging depth of 3-4 mm. The optical property measurements of various fruits obtained using our system were in close agreement with the reference values provided by the integrating sphere (IS). The mean measurement error of the absorption coefficient was approximately 0.002 mm^-1, while that of the reduced scattering coefficient was approximately 0.02 mm^-1. In the application case of peach firmness prediction, the developed model achieved a coefficient of determination for prediction of 0.786. These results demonstrate that our system is more accurate than existing multiwavelength SFDI devices. This improvement indicates that the extended spectral range of the proposed SFDI system provides richer tissue information, thereby highlighting its potential for fruit quality evaluation. More importantly, this work establishes a new paradigm for SFDI instrumentation by transitioning from fixed multispectral sensing to customizable, spectrally continuous imaging, thereby broadening its applicability in the nondestructive evaluation of agricultural products and potentially other biological tissues.