Electron multiplier, incorporated into the camera tube of an ultrasonic imaging system, improves resolution, effectively shields low level circuits, and provides a high level signal input to the television camera. It is effective for inspection of metallic materials for bonds, voids, and homogeneity

Berger, H.

Collis, W. J.

Jacobs, J. E.

English

NASA Technical Reports Server

April 1968	 Brief 68-10088 
•
OF C
AEC-NASA TECH BRIEF 
FES
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New Camera Tube improves Ultrasonic Inspection System 
Image of Raw
To Ultrasonic Generator 
)	 Accelerating Mesh
Video	
Electron Multiplier I Amplifierl  
Flaws 
-	
- - - - Stabilizing Mesh 
Electron 
flT lGun 
Piezoelectric Plate 
ULTRASONIC CAMERA TUBE 
The problem: 
To improve resolution and reduce noise sensitivity 
of an ultrasonic television inspection system used in 
the nondestructive testing of metals. In existing 
systems, the camera tube sensitivities are limited by 
the low input load resistance of the associated 
amplifiers. Also, interference patterns from the 
transmitter itself are common noise sources at a level 
of 10-8 ampere of signal current. Both factors 
combine, making effective shielding of equipment 
from spurious noises very difficult. 
The solution: 
An electron multiplier, incorporated into the 
camera tube of an ultrasonic imaging system, im-
proves resolution, effectively shields low level cir-
cuits, and provides a high level signal input to the 
television camera. The electron multiplier provides 
amplification of the secondary electron beam within 
the camera tube. The signal currents are amplified 
10- 5 to 10- 6 times greater than the threshold value.
Li Transmitting 
Oect Crystal 
lonitor	
Water Tan k 
Focusing &
	 Gun	 Piezoelectric Target 
Deflection	 Of Pickup Tube 
Circuit
ULTRASONIC INSPECTION SYSTEM 
The tube sensitivity is set by the piezoelectric plate's 
ability to modulate the secondary emission electrons 
without the need for a great deal of shielding, as is 
the case for tubes without the multiplier. The multi-
plier also serves as a wide-band amplifier having 
extremely good noise characteristics. 
The improved system is effective for inspection of 
metallic materials for bonds, voids, and homogeneity, 
which are not detectable by conventional methods. 
The system is currently being evaluated for applica-
tion in medical diagnostics. 
How it's done: 
The improved ultrasonic camera tube is shown on 
the left. The accelerating potential of the electron 
gun is 1000 volts. I pr is the primary electron current; 
Is is the secondary emission current. The accelerating 
mesh is +400 volts relative to the stabilizing mesh. 
The electron multiplier has 10 stages with 100 volts/ 
stage. 
Adk	 (continued overleaf) 
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The secondary electrons, produced on the 2-inch 
diameter, barium titanate piezoelectric target by the 
high velocity electron scanning beam, are accelerated 
into the electron multiplier by the accelerating mesh, 
producing high level output. The secondary electron 
beam is modulated on a point-to-point basis by the 
voltage generated by the piezoelectric target. The 
target is irradiated by an impinging ultrasonic field. 
The diagram of the entire ultrasonic imaging inspec-
tion system set up for a through-transmission inspec-
tion is shown on the right. (Reflection techniques may 
also be used.) The far field ultrasonic pattern pro-
vides a uniform ultrasonic intensity for a shadow-type 
image. 
Following detection and amplification in the pickup 
tube, the amplified video signal is presented by a 
conventional television system. The image of alcy 
discontinuity is then reproduced on the observation 
monitor. 
Numerous tests were run, comparing this system 
with other ultrasonic methods and X-radiographic 
techniques. It was shown capable of detecting flaws 
within metals to a degree equal to or better than all 
other methods tested. 
Notes: 
I. Additional details are contained in: An Evaluation 
of an Ultrasonic Inspection System Employing 
Television Techniques, by Dr. J. E. Jacobs, W. E. 
Collis, and Harold Berger, Argonne National 
Laboratory, Argonne, Illinois. This article is pub-
lished in the May 1964 issue of Materials Evalua-
tion. The report includes a review of articles 
concerning research in the ultrasonic imaging 
field. Nondestructive test procedures are discussed.
This information would be of interest to users and 
manufacturers of nondestructive test equipment. 
Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B68-10088 
Source: J. E. Jacobs and W. J. Collis

Northwestern University

and H. Berger

Metallurgy Division

Argonne National Laboratory

(A RG-90237) 
Patent status: 
Inquiries about obtaining rights for commercial use 
of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 68-10088	 Category 01


New camera tube improves ultrasonic inspection system

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