Simple Spectrograph Research Articles

Electrostatic charged-particle spectrograph made up of discrete plane and box electrodes

A simple spectrograph is suggested for rapid analysis of the charged particle beam energy. The device is protected against the penetration of stray self-fields and extraneous fields into its operating region. A distinctive feature of such a spectrograph is that potentials applied to different parts of the split plane electrode vary in proportion to the square root of the distance from the frontal end electrode to the middle of the respective part. Optimal operating conditions for the spectrograph are found using computer simulation. Under these conditions, the range of energies recorded simultaneously covers two orders of magnitude, which is several times larger than the maximal range of the spectrographs currently available.

Real-Time Circular Dichroism Spectrograph Based on a Single Liquid Crystal Diffractive Element

A simple spectrograph based on a polarization grating has been developed for real time measurements of circular dichroism. The main and unique element is a liquid crystal replica of a polarization grating recorded by means of holographic techniques in thin films of organic materials. This gratings offer long time stability and high diffraction efficiency. Due to the peculiar features of the grating, the circular dichroism of any system can be easily evaluated measuring only the intensities of the first order diffracted beams, just locating the grating after the investigated system. The spectral selectivity of the grating allows simultaneous measurements for all wavelengths of the spectra by using two linear Charged-Coupled devices.

A Complementary Metal Oxide Semiconductor sensor array based detection system for Laser Induced Breakdown Spectroscopy: Evaluation of calibration strategies and application for manganese determination in steel

This paper describes a low cost detection system for Laser Induced Breakdown Spectroscopy based on a simple spectrograph employing a conventional diffraction grating and a non-intensified, non-gated, non-cooled 1024 pixel Complementary Metal Oxide Semiconductor linear sensor array covering the spectral range from about 250 to 390 nm. It was employed in conjunction with a 1064 nm, 5 ns pulse duration Nd:YAG laser source for analyzing steel samples using the integration of 300 analysis pulses (35 mJ each). That led to gains in the signal-to-noise ratio of approximately 3 and 16 for Mn and Fe peaks, respectively, in addition to gains in the emission intensities of about 5.3, both in comparison with the integration of just 50 analysis pulses. The acquired emission spectra were used for Mn determination, in the range from 0.214 to 0.608% m/m as previously determined by ICP OES, evaluating different univariate (at different discrete wavelengths) and multivariate (over different spectral ranges) calibration strategies. The best results, using a PLS calibration model in the spectral range from 292.9 to 294.5 nm (related to Mn emission peaks), had relative errors of prediction of the Mn concentrations, for samples not employed in the calibration, from 0.3 to 7.3%, which are similar to or better than those obtained for Mn determination in steel using higher cost detection systems. The successful analytical application of the new detection system demonstrated that the performance of low cost detection systems can be very good for specific applications and that its low resolution and sensitivity can be at least partially compensated by the use of chemometrics and the integration of analysis pulses.

Evaluation of ozone column amount from the solar backscattering spectra measured with a spectrograph onboard an aircraft

Abstract Slant column amounts of ozone were evaluated from the solar backscattered spectra measured with a simple spectrograph onboard an aircraft over the Pacific Ocean south of Japan in January 2002. A least-squares fitting method optimized on the basis of Bayesian statistics was developed to evaluate them, and the random error in the fitting was about 2.4%. The evaluated slant column amounts of ozone were compared with those calculated from the total ozone data measured with the Total Ozone Mapping Spectrometer (TOMS) on the same day. The differences between the two ranged from a few percent points to more than 20%, and they increased when a small wavelength deviation in the spectrograph occurred due to the aircraft vibration. Excluding the error due to this wavelength deviation, instrumental and systematic errors were estimated to be less than 10%, demonstrating that this airborne measurement with the spectrograph and the developed fitting method could evaluate the ozone column amount with a good accuracy.

A Cinema-Spectrograph for Photographing Rapid Spectral Sequences*,**

A simple spectrograph designed around a 16-mm movie camera is described. The spectrograph was built for the purpose of obtaining spectrograms from light sources showing transient phenomena, in particular such light sources as the new types of rocket and jet combustion engines. The study of the light emitted from an acetylene-oxygen flame as a function of time illustrates its usefulness.