Abstract: Image display apparatus comprising a projector, at least one primary modulator (4,6,8) for modulating light, an auxiliary modulator (36) for modulating the light modulated by the primary modulator, and an optical device (32) for relaying the light modulated by the primary modulator to the auxiliary modulator (36), the optical device (32) comprising a concave mirror and at least one refractive element.

Abstract: An eyepiece (2) for viewing a flat image, which eyepiece (2) has a wide field of view and which eyepiece (2) comprises a cemented doublet of reflecting and refracting optical components, the reflecting and refracting optical components being such that they are each of a different refractive index whereby chromatic aberrations and spherical aberrations are reduced.

Abstract: Image display apparatus (26) comprising a display panel (28), a screen (30), and image relay apparatus (2), the optical relay apparatus (2) comprising at least one aspherical polymer lens (8, 10, 12,14) and at least one spherical glass lens (4, 6), the said lenses being such that an image is able to be relayed from the display panel to the screen with a predetermined distortion, the optical relay apparatus (2) being such that it has a final aspherical polymer lens (14) which is the said aspherical polymer lens (8, 10, 12, 14) or one of the said aspherical polymer lenses, the final aspherical polymer lens (14) has a first depression (16) on a first side (18) and a second and larger depression (20) on a second side (22), the first side (18) being nearer to the display panel (28) than the second side (22), and the final aspherical polymer lens (14) directs light towards the screen (30) such that the direction of light rays complements the operation of an eyepiece used to view the screen (30).

Abstract: An eyepiece (2) for viewing a flat image, which eyepiece (2) has a wide field of view and which eyepiece (2) comprises a cemented doublet of reflecting and refracting optical components, the reflecting and refracting optical components being such that they are each of a different refractive index whereby chromatic aberrations and spherical aberrations are reduced.

Abstract: Diver communication equipment comprises a diver's helmet having a display consisting of a monitor, a prism, a relay lens and an eyepiece. The relay lens and the eyepiece are mounted in a tube which extends into the helmet through a sealing bush located in place by a nut. The helmet also caries a television camera and a light. By looking up at the eyepiece, the diver can see, through one eye, video images from the monitor derived from the camera or from another camera located topside of some other graphical or numeric information derived either from other devices subsea or other sources located topside. In a modification, the monitor occupies the tube.