GB498419A - Improvements in or relating to optical projection systems - Google Patents
Improvements in or relating to optical projection systemsInfo
- Publication number
- GB498419A GB498419A GB2595437A GB2595437A GB498419A GB 498419 A GB498419 A GB 498419A GB 2595437 A GB2595437 A GB 2595437A GB 2595437 A GB2595437 A GB 2595437A GB 498419 A GB498419 A GB 498419A
- Authority
- GB
- United Kingdom
- Prior art keywords
- image
- lenses
- lens
- projection
- axis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
498,419. Optical-projection systems. KAPELLA, Ltd., WARMISHAM, A., and REASON, R. E. Sept. 24, 1937, Nos. 25954/37, 29572/37, and 19544/38. [Class 97 (i)] The projection of an image of an object lying in a surface inclined to the direction of projection on to an image surface also inclined to the direction of projection, is effected by means of a system of lenses so arranged as to collimate the principal rays in the object and image spaces and thus to produce an image free from keystone distortion due to the oblique distortion. Fig. 1 shows a symmetrical system for producing an image at unit magnification, comprising a projection lens A and two equal collimating lenses B<1>, B<2> having their principal foci at the nodal points A<1>, A<2> of the lens A. The lenses B<1>, B<2> are spherically corrected with respect to the nodal points A<1>, A<2> respectively, and fulfil the sine condition within the angle subtended by the lens A. The object and image planes D, C are equally inclined to the axis of the system and the image is undistorted. This system can be adapted for producing a focused image free from keystone distortion at other than unit magnification by using lenses B<1>, B<2> of different focal lengths and arranging the system so that the ratio of the tangent of the angle between the object plane and the axis to that of the angle between the image plane and the axis is equal to the magnification. The image so produced will suffer from rectangular distortion, and this defect can be remedied by modifying the system by tilting one or more of the lenses. The system shown in Fig. 2 comprises two collimating lenses F<1>, F<2> of different focal lengths having their axes coincident with that of the system, and a projection lens E which is tilted through such an angle that the object and image planes G, H are equally inclined to the axis. To correct for aberrations in this system, the lens E is preferably an anastigmat and may consist of a divergent component between two symmetrically arranged convergent components. Instead of tilting the lens E, the lenses F<1>, F<2> may be tilted through the same angle. As a further alternatlive all three lenses are equally tilted, in which case the lenses F<1>, F<2> are preferably anastigmats. The above arrangements are suitable for projection on to a screen &c. ; an arrangement in which the image can be directly viewed by an eyepiece is shown in Fig. 5. An image of the object D is produced by the system B', A, B<2> of Fig. 1 on a transparent surface C<2> on which graduations are marked. An image of the surface C<2> is produced on a surface P at right-angles to the axis of the system by a lens O, so that this image can be viewed by an eyepiece Q, the lens O being tilted to enable a focused image to be obtained at P. This image is distorted, but the image of the graduations is equally distorted so that the graduations can be used for measurements of the final image. This image may be corrected for keystone distortion by a field lens R. Specifications 498,377, 498,378, 498,382, 498,420, and 498,458 are referred to.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2595437A GB498419A (en) | 1937-09-24 | 1937-09-24 | Improvements in or relating to optical projection systems |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2595437A GB498419A (en) | 1937-09-24 | 1937-09-24 | Improvements in or relating to optical projection systems |
Publications (1)
Publication Number | Publication Date |
---|---|
GB498419A true GB498419A (en) | 1939-01-09 |
Family
ID=10236012
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB2595437A Expired GB498419A (en) | 1937-09-24 | 1937-09-24 | Improvements in or relating to optical projection systems |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB498419A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2343526A (en) * | 1998-11-04 | 2000-05-10 | Int Optics Limited | Objective arrangements for projectors |
-
1937
- 1937-09-24 GB GB2595437A patent/GB498419A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2343526A (en) * | 1998-11-04 | 2000-05-10 | Int Optics Limited | Objective arrangements for projectors |
US6527394B1 (en) * | 1998-11-04 | 2003-03-04 | International Optics Limited | Objective arrangements |
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