[Coma and resolution in wide spectral region Czerny-Turner spectrometer].

The Czerny-Turner layout, which is most frequently used in miniature spectrometers, should follow Shafer's coma-free condition and Fastie's flat-field principal to eliminate the central wave's primary coma and maximize its resolution. However, the design process does not take the comas and resolutions at non-central waves into consideration. Based on the theory of primary coma in reflection optical system, the present paper points out that in the crossed beam design, the resolutions at wide 'spectral region present a "V" shape, while in the M design, the resolutions change little over the whole region, and present an approximately straight line shape, so the latter kind of spectrometer maintains a far more consistent resolution than the former one. Accordingly, this paper designs two kinds of spectrometers with spectrum regions from 400 to 600 nm, and carries out theoretical simulation and contrast experiment. The result demonstrates that for the two designs the resolutions at the fringe wavelength are 3.8 times and 1.5 times respectively that at the central wavelength, which accords with the conclusion of the theoretical simulation.

[Blind deconvolution algorithm for spectrogram super-resolution restoration].

Deconvolution is an important way to realize spectrogram super-resolution restoration. Blind deconvolution is superior to the traditional one in that it does not need a well prepared convolution core. Taking advantages of the features of spectrogram and the existing achievements of spectrogram deconvolution, the authors bring forward a scheme to adapt the space domain iterative blind deconvolution method to spectroscopy application. Moreover, after probing into the spectrogram degradation described by convolution, computational models for spectrum convolution and Gauss fitting are worked out to meet the requirements of blind deconvolution algorithm. Accompanying results are simulations with MATLAB7.0. They shows that for the given spectrum and point spread function of Gauss type the blind deconvolution algorithm works well and a resolution enhancement of 30% can be achieved under a signal-to-noise ratio of 50 dB.

[The effect of the photoelectric detector on the accuracy of the spectrometer].

An optimized photoelectric detector will increase the precision of a spectrometer, thus indicates an important way to develop high performance spectrometer. With an eye to this, a model describing the process that spectrogram is integrated and sampled by photoelectric detector and restored after low-pass filtering is developed. Based on the model, the influence of the characteristic parameters of the detector on the spectral line in the frequency domain is analyzed and the relation between the full width half maximum (FWHM) of the spectra line and the integral interval, sampling space and sensitivity of the detector is deduced. The conclusion indicates that both the integral interval and sampling space should be 1/6 of the FWHM for a spectral line with gaussian profile as a result of compromise between accuracy and feasibility. Moreover, the critical point deciding the right situation for scanner and array detector is given. Other guide line to optimize the photoelectric detector and increase accuracy is suggested also.