Available online
Description
Key concepts introduced in the course are reviewed. 1. The effect of a simple object on transmitted illumination. 2. Images of transmitted beams on a screen. 3. Holographic images using light. 4. H...olographic images using sound.
Key concepts introduced in the course are reviewed. 1. The effect of a simple object on transmitted illumination. 2. Images of transmitted beams on a screen. 3. Holographic images using light. 4. H...olographic images using sound.
| Module code and title: | ST291, Images and information |
|---|---|
| Item code: | ST291; 17 |
| First transmission date: | 17-10-1977 |
| Published: | 1977 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:00 |
| + Show more... | |
| Producer: | Tony Jolly |
| Contributors: | Stuart Freake; Alan Walton |
| Publisher: | BBC Open University |
| Keyword(s): | Diffraction patterns; Holography; Spatial filtering; Transmitted illumination; Ultrasonic sound waves |
| Footage description: | Alan Walton introduces the programme. He discusses the effect a simple object has on transmitted illumination. Walton passes a laser through a transparency, shows an animation illustrating the output side of a cosinusoidal grating and uses a corrugated plastic model to show the practical significance of the constant in space and standing wave components. Using a graphics board to help illustrate his points, Walton discusses the effect of a change in wavelength of the object incident light and then a change in the direction of light incidence. Stuart Freake considers the nature of an image when transmitted beams from an object fall on a distant screen. He recalls some of the diffraction patterns which were examined in earlier programmes. Stuart Freake goes on to look at optical diffraction patterns of Alan Walton and Barrie Jones pointing out the main differences between the two patterns. Stuart Freake next explains how, with the use of lenses, a diffraction field is changed to produce an image field. He points out why a perfect image is not obtained. Using micrographs of cells under bright field and then dark field illumination, Stuart Freak demonstrates a technique, spatial filtering, which allows images to be modified. More shots of micrographs, this time of an aluminium specimen and then diffraction patterns of the same specimen. Keith Hodgkinson discusses the difficulty of imaging a three dimensional object on a photographic plate so that information is not lost. He explains how a hologram gets around this difficulty and goes on to discuss how a hologram is constructed. Hodgkinson demonstrates by showing plane, vertical fringes resulting from laser light 'beating' itself. Hodgkinson goes on to discuss briefly, the generation of holograms using coherent ultra-sound. Alan Walton sums up. |
| Master spool number: | DOU2431 |
| Production number: | 00525_1257 |
| Videofinder number: | 2128 |
| Available to public: | no |
