A review is given of the factors contributing to the noise and to the limitations in resolving power. Their mutual dependance is expressed in simple formulas.
The factors contributing to the limitations in resolving power at infinitely narrow slits are discussed in detail. Their sum is approximated by a Gauss curve of width s0. The finite slit width sg adds to s0 giving an effective slit width seff, where seff2=s02+sg2. Expressions are given for the energy from the glower traversing the spectroscope and for the noise generated in the detector amplifier system. From these the signal-to-noise ratio and the relative random errors in D due to noise are expressed in terms of sg, transmittancy of sample, filter time constant, and a few functions characteristic of the spectroscope. Optimal scanning conditions are discussed on this basis. It is shown that sg in most cases ought to have a magnitude between s0/2 and s0.
© 1953 Optical Society of AmericaFull Article | PDF Article
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