The design of a high-performance hyperspectral imaging spectrometer with a large field of view and broad spectral range is crucial for advanced environment monitoring and remote sensing. Such instruments are needed on airborne and spaceborne platforms for observing environmental features, disasters, agriculture, and urban areas in detail. However, conventional hyperspectral systems struggle to simultaneously achieve wide spectrum coverage, high spectral resolution, and large field coverage. Traditional designs (e.g., Offner spectrometers) can reach a spectral resolution of 2-5 nm in the ultraviolet to near-infrared range with high optical throughput, but they often suffer from complex alignment, high cost, and limited numerical aperture. To address these challenges, this study aims to develop an optical system for a hyperspectral imager that covers a broad waveband (350-1000 nm) with a wide field of view (30°) and high resolution, providing an effective new method for ground object observation in environmental monitoring.The optical system is divided into two parts: the telescope system and the imaging spectrometer, which are designed separately and then coupled at the slit to achieve the complete system. The telescope system adopts an off-axis two-mirror optical configuration, with the design operating in the ultraviolet-visible-near-infrared spectrum (350 nm to 1000 nm), a field of view of 30°, and an F-number of 2.5, ensuring high optical throughput. The imaging spectrometer improves upon the traditional Dyson configuration by replacing the reflective grating with a combination of a lens and a reflective grating. Specifically, the original reflective grating is replaced with a special combination where the front surface is a transmissive lens, and the rear surface serves as a grating diffraction element. This design overcomes the engineering limitations of the traditional Dyson configuration. The modified structure maintains concentricity while addressing aberrations caused by air gaps. Optical design software was used to optimize both the telescope and spectrometer systems, minimizing the aberrations across the entire field of view and spectrum. Finally, a prototype was built, and key performance tests (spectral resolution and imaging) were conducted to validate the design.The optical performance of both the telescope and imaging spectrometer systems meets the design requirements. Figure 2 shows the Modulation Transfer Function (MTF) of the telescope system across the full field of view and full spectral range, where the MTF at the Nyquist frequency of 56 lp/mm corresponding to the detector is greater than 0.7, indicating excellent imaging quality. The spectrometer design likewise achieves MTF above 0.7 across the 350-1000 nm band with very small spot sizes due to effective aberration correction. When integrated, the full system still maintains an MTF above 0.5 at the detector’s Nyquist frequency (50 lp/mm) in all fields (Fig.8). The corresponding spot diagrams confirm that image spots are confined within 16 μm, validating the combined system’s optical quality. In laboratory tests, the prototype instrument’s spectral resolution was measured to be approximately 2.1 nm across the band (Tab.1), in close agreement with the 2.07 nm design prediction. In an outdoor imaging demonstration, the sensor captured clear hyperspectral images with fine detail (Fig.12), demonstrating a spatial resolution on the order of 1mrad. These results confirm that the developed hyperspectral system meets its design requirements and can effectively capture both spectral and spatial information of environmental targets.This study developed a large field-of-view, broadband hyperspectral imaging sensor optical system that meets the stringent requirements for environmental observation. By combining a wide-aperture off-axis two-mirror telescope and an improved Dyson imaging spectrometer, the design achieves both high spatial resolution and high spectral resolution over the 350-1000 nm waveband. The key innovation lies in the modified Dyson spectrometer with a lens-grating element, which allows a larger numerical aperture and a practical configuration without sacrificing optical performance. The final instrument achieves a spectral resolution of approximately 2.1 nm and a spatial resolution of 1mrad, as validated by both simulation and prototype testing. The extended field and broad spectral capabilities of this hyperspectral imager make it highly suitable for airborne or satellite-based environmental monitoring. The outcomes of this design provide a strong engineering basis and reference for future development of advanced hyperspectral imaging systems in remote sensing.