Journal of the Society of Motion Picture Engineers (1930-1949)

Page scan 000566 from Journal of the Society of Motion Picture Engineers

Record Details:

Title:
Journal of the Society of Motion Picture Engineers
Date:
1930-1949
Publisher:
New York, N.Y. : The Society
Volume:
Journal of the Society of Motion Picture Engineers
Leaf #:
000566
Language:
English
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Prelinger Library
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
The Journal of the Society of Motion Picture Engineers (SMPE)Êdocuments the technological progress of the film industry, highlighting technical developments in production and exhibition. Of special interest are articles about special effects, theater practices, lighting, and the introduction of the 16mm format. Initially titled "Transactions of the Journal of the Society of Motion Picture Engineers."Digitized by the Prelinger Library and the Library of Congress Motion Picture, Broadcasting and Recorded Sound Division.
Date Added:
July 19, 2022
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1949 CATHODE-RAY OSCILLOGRAPHY 563 Whenever recordings are made which include low plus high writing rates such as flat-topped, relatively long pulses with relatively fast rise times, the slower portions of the pattern become considerably overexposed causing halo around the cathode-ray-tube trace. This halo is a well-known phenomenon caused by the total reflection of the light from the cathode-ray-tube spot at angles beyond the critical angle for the glass-air interface.4 This halo can be eliminated completely by effectively making the glass face as thick, approximately, as the nominal radius of the tube face. This is a somewhat impractical solution, (b) (c) Fig. 15 — Effect of screen-coating procedure on halo: (a) flowed screen; (b) settled screen; (c) with plastic face plate. but the same effect may be obtained by placing in optical contact with the screen a cup-shaped lens of plastic, the contact being maintained by means of a liquid of suitable refractive index. Some work has been done on the cementing of plastic to the glass face in order to eliminate halo. The magnitude of the effect depends to a great extent on the proportion of the light which reaches angles near the critical at the glass-air interface. This effect may be minimized by a choice of screen-coating procedure which directs a large proportion of the light foreward rather than at angles close to the critical. Fig. 15 shows