An analog data processor for chart records using a multielement photodetector

The apparatus, which is capable of computing the convolution integrals of electrically programmed functions and graphical data in the form of recorder traces, is described. The recorder trace is scanned by means of an optical scanner involving a multielement photodiode array. The signals from the scan head, which correspond to trace positions on the chart, are processed with analog circuits so arranged that the weighted moving average is accomplished. The over-all accuracy of the system, including the long-term drift of analog computing electronics, is better than 0.5%. To demonstrate the performance, spectroscopic data provided with conventional ir spectrophotometers are processed. This simple processor can also be utilized as a function generator or an instrument simulator.

Improved double beam, vacuum far infrared spectrophotometer

A double beam far ir spectrophotometer was improved in order to give more convenience and higher performance. The instrument is evacuable and the sample chamber alone can also be purged with dry air to remove water vapor. Three photometric systems, i.e., conventional double beam, double beam double chopping, and single beam systems can be selected for versatile measurements. The use of an efficient transmission filter system, not involving deliquescent crystals, results in many operational advantages. Accordingly, high resolution can be obtained through the entire spectral region from 400 cm(-1) to 30 cm(-1) Moreover, 30-min scan over the entire spectral region is achieved by completely automatic operation with a refined control system.

A far infrared interferometric spectrometer with a special electronic computer

A far ir interferometric spectrometer with a special electronic computer has been constructed. The interferometer is of the conventional Michelson type. The electronic computer, which consists of an analog computer to introduce apodization and a digital computer to calculate the Fourier cosine transform, is fed with the detector output of the interferometer and is operated by electric pulses from a moiré fringe counter that is part of the mechanism that measures the path difference in the interferometer. The digital computer makes the calculation in parallel for each of one thousand spectral positions during the scanning of the interferogram. It takes 0.45 sec for the calculation at each path difference. A spectrogram can be obtained in 10 min; this includes calculations at one thousand path differences and 2 min for recording. During the scanning, values stored in the memory corresponding to the one thousand spectral positions can be displayed on a synchroscope in order to provide a spectrogram that is low in resolving power at the beginning and high at the end of the scan. Some results obtained with water vapor absorption are shown.