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5.0 NATIONAL REPORTS -- STANDARDS AND ACTIVITY 
5.1 Great Britain: The following brief summary covers the work 
in the United Kingdom. 
5.1.1 Standards Activity 
Government and commercial agencies have been using photo- 
electrie techniques for over a decade for measuring the line spread 
function from which the OTF is obtained by Fourier analysis. 
The method developed at the Royal Aircraft Establishment has resulted 
in British Standard 4779 (1971), "Recommendations for Measurement 
of the Optical Transfer Function of Optical Devices.” The RAE 
equipment for measuring OTF is now organized in collaboration 
with the National Physical Laboratory as the standard of reference 
for OTF measurements carried out under the control of the British 
Calibration Service. This service issues publications 0702 and 
0751 which set out the general conditions for testing and approval 
of a laboratory's equipment and techniques certifying their capability 
to perform optical transfer function measurements. 
These critiques rate laboratory capability in accordance 
with their ability to meet the values set by the reference laboratory 
(RAE) for the OTF testing of standard lenses. In addition, there 
are specified requirements, such as the necessity that the test 
equipment be mechanically accurate and repeatable, the environment 
be controlled, the spectral characteristics of the source and 
sensor be known, and linearity be proved or calibrated. 
SIRA Institute Image Assessment Group is a UK collaborative 
activity which has headed many qualitative investigations on OTF. 
Their findings frequently written in conjunction with RAE are 
published in papers which are excellent references for those 
establishing or controlling an OTF test laboratory. These papers 
include: 
a. Accuracy in Image Evaluation: Setting up an OTF Standards 
Laboratory. 
b. Influence of Optical Bench Errors on Accuracy of OTF 
Measurements. 
c. The Use of Simple Optical Systems for verifying the 
Accuracy of OTF Equipment. 
d. The Use of Standard Test Lenses for Verifying the 
Accuracy of OTF Equipment. 
e. Specifications for Checking the Performance of MTF 
Equipment at Large Field Angles using a Gimbal Mounted f/4, 200 
mm doublet lens. 
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