Abstract: A lens group for an endoscope or microscope, comprising one or more lens elements, each of uniform refractive index, adapted to: i) focus, with high wavefront aberration correction, driving or excitation light received from an exit tip of an optical waveguide (such as an optical fiber) located substantially against a proximal surface of the lens group to a point observational field with narrow point spread function beyond a distal surface of the lens group (such as outside an optical window located distally relative to the distal surface); and ii) transmit, with high wavefront aberration correction, fluorescence or reflected return light received by the distal surface from the point observational field (and its neighborhood defined by the fluorescence wavelength point spread function) back to the exit tip of the optical waveguide at the fluorescence wavelength.

Abstract: A lens group for an endoscope or microscope, comprising one or more lens elements, each of uniform refractive index, adapted to: i) focus, with high wavefront aberration correction, driving or excitation light received from an exit tip of an optical waveguide (such as an optical fibre) located substantially against a proximal surface of the lens group to a point observational field with narrow point spread function beyond a distal surface of the lens group (such as outside an optical window located distally relative to the distal surface); and ii) transmit, with high wavefront aberration correction, fluorescence or reflected return light received by the distal surface from the point observational field (and its neighbourhood defined by the fluorescence wavelength point spread function) back to the exit tip of the optical waveguide at the fluorescence wavelength.

Abstract: A microscope, endoscope or optical coherence tomograph, comprising a light source, a flexible light transmitter (18) for receiving and transmitting light from the light source, an optical element (20) with a forward end (30) for receiving the light from the light transmitter (18) and a rear wall (26) having an internal surface for reflecting the light laterally, and an external sleeve (14) enclosing the optical element (20) and transparent to the light in at least a region of the sleeve where the light is directed by the internal surface (26). The internal surface (26) has an optical figure suitable for focussing the light to an observational field (28) external to the sleeve (14). A confocal configuration may be used.

Abstract: Twin roll caster for casting metal strip comprises casting rolls (11) between which is formed a casting pool (16) of molten metal. The casting pool is confined at each end of the roll nip by end closure plate (22). Alternating electric current is supplied to electrical conductors (33) disposed outside the closure plate (22) so as to generate an electromagnetic field which extends through the closure plate and pushes back molten metal at the conjunctions (27) between the closure plate (22) and the rolls (11).