i MDDC - 1052 UNITED STATES ATOMIC ENERGY COMMISSION A COMBINED SHUTTER AND PROJECTION DEVICE FOR THE ALIGNMENT OF ELECTRODES IN SPECTROGRAPHIC ANALYSIS by A. Lee Smith V. A. Fassel Iowa State College This document consists of 4 pages. Date of Manuscript: Unknown Date Declassified: June 12, 1947 This document is issued for official use. Its issuance does not constitute authority to declassify copies or versions of the same or similar content and title and by the same author(s). Technical Information Division, Oak Ridge Directed Operations Oak Ridge, Tennessee Digitized by the Internet Arcliive in 2011 witli funding from University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation http://www.archive.org/details/combinedshutterpOOiowa A COMBINED SHUTTER AND PROJECTION DEVICE FOR THE ALIGNMENT ' OF ELECTRODES IN SPECTROGRAPHIC ANALYSIS By A. Lee Smith and V. A. Fassel It is well known that in quantitative spectrographic analysis the position and spacing of the elec- trodes are quite critical if reproducible results are to be obtained. Proper alignment is usually made by means of an auxiliary lens which projects the electrode image on a previously marked screen.''^ In some cases the electrodes are quickly positioned after the exposure has been started, or for more careful work, the electrodes are aligned before arcing by the use of a lamp placed be- hind the electrodes to project their image. ^)* Such a device requires manual operation of a lamp or mirror, and if many samples are run the time consumed by this adjustment may be considerable. The apparatus described here (Figure 1) is almost instantaneous in action and is operated electri- cally by conveniently placed push buttons. Furthermore, it provides an excellent shutter for spectro- graphs not already so equipped. It operates on the principle that an iron rod placed in a solenoid tends to center itself when current, alternating or direct, is passed through the windings. The assembly is mounted on a 1/8 inch brass plate which is bolted to an optical bench carriage. The double solenoid is made by winding enough No. 32 cotton-covered copper wire on a four inch brass tube with bakelite spacers to give a resistance of about 80 ohms in each section (Figure 2). The soft iron core,four inches long and 1/4 inch in diameter, should slide freely in the tube. The polished steel mirror is mounted on an arm which is free to rotate through a 45 -degree angle, thus swinging the mirror in and out of the optical path as the position of solenoid core changes. A spring bears against the notched disk which is a part of the mirror arm, and insures the mirror's stopping in the same position each time. A metal stop is placed near the edge of the base plate to limit the motion of the mirror. The lamp used on the instrument described is a 30 watt toy projecter bulb of type S-11, although any similiar lamp may be used: The socket is mounted on an insulated platform (not shown in the drawings) which is fastened to the base. A cover may be placed over the lamp as indicated in Fig- ure 3, or over the whole assembly (Figure 1), with suitable holes cut for the optical path. Electrical connections may be made by means of a tube socket mounted back of the lamp. The wiring scheme is shown in Figure 4. The two sides of the double solenoid are activated by push buttons mounted in a convenient place. The authors wish to thank Mr. Lael Smith for his assistance in the construction of the instru^ ment. MDDC - 1052 [ 1 2] MDDC - 1052 Figure 1. Assembly with cover removed. MDDC - 1052 [3 MIRROR PROJECTION ' LAMP SOLFNOID 2 ^ Figure 2. Top view of projector assembly. Figure 3. Front view of assembly. 4] MDDC - 1052 Figure 4. Wiring diagram showing solenoid winding and push buttons. REFERENCES 1. Erode, W. R., Chemical Spectroscopy, P 35, 2nd ed., John Wiley and Sons, New York, 1943. 2. Clayton. W. R., J. Sci. Instruments 18: 65 (1941). 3. Scribner, B. F., Spectroscopy in Science and Industry, P 32, John Wiley and Sons, New York, 1938. 4. Torok. Tibor, Spectrochim. Acta, 2: 300-302 (1943). UNIVERSITY OF FLORIDA 3 1262 08909 7801