Broadband high-resolution line-imaging spectrometer with a large working distance range

Abstract

A broadband high-resolution line-imaging spectrometer (BHLIS) is presented, which consists of only two identical linear microlens arrays, one linear stop array, one parallel planar transmission grating pair and one area array detector. The detector is divided into many small rectangular pixel arrays, each corresponding to one calculated wavelength and one target unit. The BHLIS can achieve high spectral resolution (of the order of 1 nm) over a broadband wavelength range (e.g. 250 nm–380 nm, or 400 nm–700 nm) in the ultraviolet–visible spectral region. For existing imaging spectrometers, the angular resolution does not vary with the measuring distance, but the larger the measuring distance, the lower the spatial resolution. However, for all measuring distances over a large working distance range, the spatial resolution in the vertical direction of the BHLIS is approximately equal to the aperture size of a microlens, and the spatial resolution in the horizontal direction of the BHLIS is approximately equal to the distance between the centers of two adjacent microlenses in a linear microlens array. Since the aperture size of a microlens can be very small (e.g. 0.32 mm, 0.2 mm, or smaller) and the corresponding distance between the centers of two adjacent microlenses in a linear microlens array can be very small (e.g. 0.36 mm, 0.24 mm, or smaller), the BHLIS can obtain a high spatial resolution. The BHLIS is a unique concept that uses only one frame of data to obtain both broadband fine spectra (in the ultraviolet–visible spectral region) and high-resolution spatial images of a target row over a large working distance range.