A spectral imaging device (12) includes an image sensor (28), an illumination source (14), a refractive, optical element (24A), a mover assembly (24C) (29), and a control system (30). The image sensor (28) acquires data to construct a two-dimensional spectral image (13A) during a data acquisition time (346). The illumination source (14) generates an illumination beam (16) that illuminates the sample (10) to create a modified beam (16I) that follow a beam path (16B) from the sample (10) to the image sensor (28). The refractive, optical element (24A) is spaced apart a separation distance (42) from the sample (10) along the beam path (16B). During the data acquisition time (346), the control system (30) controls the illumination source (14) to generate the illumination beam (16), controls the mover assembly (29) (24C) to modulate the separation distance (42), and controls the image sensor (28) to capture the data.