Part I Fu ndam en tals and Ins tru m e n tu t io n 28 5 Data Processing 5.1 EMISSION SPECTROSCOPY Paksy ( 8 0 6 ) has used t h e double standard evaluation method for t h e spectrographic analysis of steels and a new method f o r handling data f r o m t h e capillary arc source has also been demonstrated (897). Evaluation of photographic plates has been automated b y means of a magnetic tape programmable densitometer (1 87). A "Steinheil" spectrocomparator-densitometer allowed qualitative and quantitative analysis t o be performed o n spectral films o r plates irrespective of t h e spectral dispersion together with t h e evaluation of back- ground and line densities.The measurement programme manually set f o r t h e first spectrum was stored o n a magnetic tape recorder and automatically applied to t h e subsequent spectra. An automatic densitometer was constructed b y a group handling a daily average of 2 3 0 emission and mass spectra plates (602). With t h e high scanning speed of 1 c m s-l a 25 cm spectrum measured a t 5 g m intervals yielded information f o r 50,000 measuring points. Out of this abundance of data all that was relevant t o t h e lines needed f o r qualitative and quantitative analysis was extracted b y a n analogue t o digital converter and a P9205 computer (16K 16 bit words) coupled t o t h e measur- ing instrument. The computer programme was given f o r this data reduction (600) which was performed simultaneously with t h e reading because of t h e reading speed and limited computer memory.Another computer orientated rnicrodensitometer has been described (405) and flexible (762) off line (601) uses of data processing included. A device including lines of known densities was used t o hold film (679) so t h a t semi-quantitative analysis was possible. Lavaud (1063) has used a time-sharing computer f o r densitometric data treatment in photographic emission spectroscopy. A description of t h e use of a computer for operating a direct reading spectrometer (186) was given with regard t o convenience and speed and in terms of increased precision. A Polyvac 1.5 m E l 0 0 0 (661 773 1 0 8 2 ) with a computer replacing t h e usual electronic console has been described.Fixed calibration curves were used f o r all elements with rotational and translational corrections f o r matrix effects. The use of basic calibration curves with a computer system t o adapt spectrometric analysis t o t h e demands of production units in a steelworks has been discussed (631). Present and f u t u r e improvements in performance of a laboratory in a BOF steel plant ( 6 3 3 ) were also discussed. The experimental application of a digital computer gave common curves for t h e analysis o f low alloy steel high alloy steel Fe glass A1 alloy and slags (630). The general curve could be approximated b y a n exponential function which indicated in accordance with t h e experimental results t h a t this method had been founded o n a general natural law.The analytical requirements (634) and t h e hardware and organis- ation of software ( 6 3 5 ) were given f o r a computerised emission spectrometry system. 29 Part I Fu n d a m en tals and Ins tru m e n tat ion Computer interpretation with t h e aid of disc storage of t h e output of a Jarrell-Ash 1.5 m Atomcounter was used for wear metals in oil (960) and for trace levels of fourteen elements in blood serum (24). Flexible computer techniques suitable for a n R & D environment (963) a small computer application (188) and a ratio output system (839) have also been described.Margoshes (68) described three instruments incorpor- ating mini computers one of which used a television camera tube as a detector. A Hewlett-Packard computer was used as a control and computation unit with an ARL 29000 spectrometer using t h e Analytica AB (Sweden) Tape machine (750). A theoretical analysis was made of t h e errors which arise due t o averaging spectral line intensities in t h e presence of electron temperature fluctuations in continuous plasma sources (432). Photographic spectrograms of Gd (I) and Gd (11) were measured in t h e 246.8-875.2 n m range using an automatic comparator and a CDC - 3200 computer (306). Wavelengths based o n a Th wavelength calibration of the spectro- grams were obtained for about 18,000 spectral lines.Systematic errors in the wave- lengths due t o shifts in t h e spectrograms of t h e Gd spectrum relative t o the T h spectrum could be greatly reduced by means of a correction deduced from discreg ancies between wavelengths obtained from different grating orders. The accuracy of t h e final wavelengths was tested using t h e combination principle and found t o be +2 X nm. 5.2 ABSORPTION SPECTROSCOPY Computers have been employed in solving many problems of a theoretical nature (3 12 378 414 450 614 6 1 6 9 0 3 9 3 2 ) b u t these calculations are outside t h e scope of this reljort.Computer calculation of analytical results will b e of benefit for large workload requirements and there is also some justification if marginal economies can be achieved using spare capacity o n a n existing computer". The current literature refers t o only a few systems covering a wide range of degree of sophistication. At one end of t h e scale t h e direct concentration readout with or without curve straightening may be adequate. Off-line data processing may b e carried o u t for example using a BASIC program (966) which computes a least squares fit t o a poly- nomial calculates concentrations in convenient units and prints out a final analytical report. A curve fitting routine for use with limited memory capacities was described (379) f o r a Wang 3 6 0 desk calculator.Here t h e calculator needed a card reading capacity of 160 logic steps and 6- 10 memory locations. Varian Techtron have published some reports of computer systems employing their model 3 4 Data Acquisition Unit (1 18 476 920 925 964). The unit accepts data from up t o four spectrometers and converts t h e data o n t o punched paper tape for processing. The use of a large computer (IBM 360 48K memory 3 discs) t o monitor many various instruments was described by Laporte (475).