Available online
Description
The programme looks at the design of a practical lens system, one which coupled to an image intensifier, will produce a night sight.
The programme looks at the design of a practical lens system, one which coupled to an image intensifier, will produce a night sight.
| Module code and title: | ST291, Images and information |
|---|---|
| Item code: | ST291; 07 |
| First transmission date: | 26-05-1977 |
| Published: | 1977 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:01 |
| + Show more... | |
| Producer: | Ted Smith |
| Contributors: | Stuart Freake; Alan Walton |
| Publisher: | BBC Open University |
| Keyword(s): | Image intensifiers; Manufacture; Night sight; Testing |
| Footage description: | Film shots of an owl taken at night at verylow levels of artificial illumination. Alan Walton shows the apparatus used to shoot this film; a trilite system. Bill Swift, Pilkington Ltd., explains how lens designers for systems such as the above draw up lens specifications. He uses a diagram and graph to help illustrate his points. Alan Walton demonstrates the problem of chromatic aberration, a common problem with lenses. Stuart Freake, with the aid of a series of ray diagrams, explains the cause of chromatic aberration and how it can be overcome. Walton, with optical apparatus, demonstrates that Stuart's explanation works in practice. Stuart Freake, again with the aid of a series of ray diagrams, looks at the problem of point spread in a lens and explains how this can be overcome. Phil Rogers, (Pilkington Ltd.), who designed the lens for the trilite system, explains how the designer goes about minimising the aberrations and optimising the modulation transfer function. Several diagrams and computer traces are used to help illustrate his points. Over commentary by Bill Swift, film shots of lenses being produced at Pilkington's. Swift explains what is happening at each step of the process. Stuart Freake explains how the finished lens is tested by measuring the modulation transfer function directly. He first points out the apparatus used for the job, and then goes on to explain the theory behind the procedure. Alan Walton sums up. |
| Master spool number: | DOU2428 |
| Production number: | FOUS727B |
| Videofinder number: | 2118 |
| Available to public: | no |
