![]() In tests with a dual-element Hg-Ar lamp (Hg-Ar lamp (model HG-1), ), the spectrometer shows the spectral data density evaluated by the highest k number, which is about 2.1 × 10 4, 2.9 × 10 4, and 2.7 × 10 4, in the 200–305 nm, 305–593 nm and 593–1000 nm wavelength regions, respectively. These sub-gratings can be chosen and arranged optimally at the blazed-wavelength λ b according to the requirement of the system design without any moving part 23, 34, 35. Individual sub-gratings with high efficiency (order of m = 1) are used to make the spectra be multiply folded and imaged simultaneously on the focal plane of the photon detector. Diffraction efficiency is relatively uniform over a broad wavelength region. A compound integrated module of the grating composed by 44 sub-gratings was designed and fulfilled to produce a spectrometer capable of identifying atoms based on their unique spectral “fingerprints” 19 with ultrahigh resolution. To exploit the usefulness and simplicity of a spectrometer in the C–T configuration while suppressing the corresponding intrinsic weaknesses arising from the coma effect, we propose a new spectrometer in an attempt to completely eliminate the root cause of the coma effect by making the off-axis angles α and β equal to 0, i.e., setting α = β = 0 in Eq. ( 1).Ī two-dimensional (2D) advanced charge-coupled device (CCD) array detector was used in the entire 200–1000 nm wavelength region with a 2048 × 2048 pixel density and 13.5 × 13.5 μm 2 pixel size 33. Therefore, according to Eqs. ( 2) and ( 3), the coma effect can be conditionally removed only at some specifically designed wavelength positions restricted within a relatively narrow spectral region.Ĭontinuous researches are being made to make the feasibility and precision of spectrometers be improved in many different configurations and applications 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32. Where m is the order of the grating diffraction and g is specified by the density of grooves of the grating (lines per mm). In the C–T configuration, the astigmatic aberrations, called the coma effect is an intrinsic issue that makes the spectral image out of focus at the focal plane of the diffracted light reflected from the mirror 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18. 1, is the most common configuration for spectroscopic analyses 1. To date, the typical Czerny–Turner (C–T) configuration 3, which consists of two spherical mirrors and a plane grating as shown in Fig. Moreover, these problems, which induce substantial measurement errors in a wide spectral range due to the strongly correlated restriction of the optical element arrangement in the system design, are difficult to solve. In optical systems, especially in high-precision optical instruments, astigmatic aberrations affect seriously the performance of the system. ![]() Since the beginning of last century, many studies had been reported trying to solve the issue of astigmatic aberrations that occur as a result of reflection or refraction at a spherical surface, shifting the incident light beam obliquely off of the homocentric axis 2. ![]() Super-high resolution optical spectrometers are significantly important for a wide range of applications in biochemical analysis, remote sensing, astronomy, and etc. ![]()
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