Journal of the Society of Motion Picture and Television Engineers (1950-1954)

resolving power of 30 lines/mm at the center and 25 lines/mm near the edge is claimed. The trend in fluorographic recording, the indirect X-ray recording method, has been toward Schmidt optics of high aperture.193 Fairchild, in this country, has disclosed such a camera. One of the important problems under investigation is the amplification and intensification of the X-ray image. Further work during 1950 indicates strides toward this realization. The use of the image-converter tube for fluorescent image intensification was described by Rawlins194 and was shown to produce an intensification of some five-hundredfold at the most, bringing fluoroscopic observations to a brightness of about 0.1 mL (millilambert). Moon,195 in this country, described the use of a scanning X-ray tube to accomplish the same end. Several general papers on the subject of the generation, of properties of X-rays, and their application were presented by Tasker,196-197 and by Meakin198 (on the subject of megavolt radiography). X-ray photographs of the vocal tract199 were used to determine the dimensions for each vowel permitting calculation of resonances in the study of normal speech. From these data, an electrical circuit has been made to produce acceptable vowel sounds. Cineradiographic devices were described by Campbell,200 L. Reynolds, et al,201 R. J. Reynolds,202 Janker,203 and in Engineer™* Essentially, all these workers are utilizing the indirect method in the studies of medical subjects to frame frequencies of the order of 50 frame/sec. In most cases, a high aperture lens of the order off/1.0 or faster, is employed. Such a device is also described in Electronic Engineering205 built by Watson and Sons in England. This device uses a 120-kv, 400-ma X-ray tube and a 35-mm motion picture camera fitted with a 4-cm jf/1.5 lens, photographing the fluorescent screen image. The X-ray tube is excited only during the camera shutter-opening. Variable frame fre quencies from 3.125 to 50/sec have been obtained. A 120-pulse X-ray tube is synchronized with a motion picture camera in a device for cine fluorography for clinical use, recently described.206 In this system, after an exposure to 4 pulses of X-ray, the current is shut off for the next 4 pulses while the film is being advanced. For circulatory studies, 15 frame/sec is used, and 30 and 60 frame/sec have been achieved, again using the indirect method. An electronically controlled cineradiographic device described by Quittner207 permits pulsing of the X-ray tube for exposures of 3/sec upward. High-speed flash radiography providing exposure durations of 1 /*sec or less were described by Pollitt208 in England, and Clark209 in the United States. Exposure durations as small as 0.1 jusec have been produced and applied in the study of explosive phenomena, projectiles in flight, and similar high-speed phenomena. Impulse X-ray tubes providing microsecond pulses were described by Funfer.210 A million-volt resonant cavity X-ray tube was described by Mills211 for use as a radiographic stroboscope for the study of objects in movement. X-ray flash photographs of explosions in water at exposure durations of 2 to 3 X 10~7 seconds were employed by Schall.212 Shock-wave velocities up to 6600 m/sec and impulsive pressures up to 190,000 atm are obtained in water by means of an explosive charge The velocity of an advancing shock wave is a function of position and density variations measured from the X-ray photographs, permitting pressure-density relations for high pressures to be calculated. The use of radioactive isotopes in industrial radiography has been given considerable impetus and was reported upon by Tenney213 of Los Alamos. Image formation by means of X-rays was further investigated by Cauchois,214 and a method permitting chemical analysis by means of X-rays was reported upon by 470 November 1951 Journal of the SMPTE Vol. 57