摘要:

The nature of photographic resolving power is discussed and attention called to the widespread misconception of it that exists at the present time. Most of the detailed discussion applies specifically to photographic objectives intended for use in aerial photography but the general approach to their photographic resolving power is applicable to studies of the photographic performance of all types of optical systems. An annulus type of target is proposed as more suitable than line targets. A method is given for the selection of the photographic focal plane when the essential requirement of the photographic use is the acquisition of maximum information. General remarks are made on the proper trend to be followed in the future design of photographic objectives. Results are presented on a study of a number of well known types of photographic objectives used for aerial photography.

ISSN:1923-4287    

DOI:10.1139/cjr46a-003

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

A new type, ultra high speed, motion picture camera is being developed in the Optics Section of the National Research Laboratories for the purpose of assisting research in the recently important fields of high speed aerodynamics, ballistics, and other high rate phenomena. It is expected that the camera will enable pictures having good resolving power to be taken at rates as high as 200,000 per sec. This report describes the principle of the camera and also describes a small experimental model that has been made. Pictures taken at the rate of 64,000 per sec. with the model are included.

ISSN:1923-4287    

DOI:10.1139/cjr46a-004

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

An experimental procedure for the design of efficient multimetal X-ray filters is presented. The applicability of such procedure is demonstrated by designing a filter for use with radiation from a Coolidge type X-ray tube operated at 100 kvp., for which it is found that 0.043 gm. per cm.2of copper backed by 0.08 gm. per cm.2of aluminum is highly effective.

ISSN:1923-4287    

DOI:10.1139/cjr46a-005

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

The theoretical response curves of finite chains of the feedback networks described by Wheeler are studied. A generalization of a standard formula for passive filters is obtained and applied to the problem. The paper presents computed reflection coefficients for various simple terminations and computed response curves for feedback chains of three, four, and five stages, using these terminations. Many of the response curves are unsatisfactory. These occur with the simpler types of terminations such as normally occur in practice. It is shown how matching at both ends of the amplifier can greatly improve the response curves with a loss of gain. Curves are also given that show the advantage of using a constant-k; half-section as a termination.

ISSN:1923-4287    

DOI:10.1139/cjr46a-006

出版商:NRC Research Press    

年代:1946

数据来源: NRC