A rotary connection for transmission of signals across an interface defined by two relatively-movable members comprising: a housing; a first element supported by said housing; a second element supported by said housing; said first element and said second element configured and arranged such that one of said first or second elements rotates about a central axis (x-x) relative to the other of said first or second elements; a rotary interface between said first element and said second element; said first element comprising: an input electrical lead; an electrical-to-optical E/O converter coupled to said input electrical lead and having an optical source; a transmitting lens coupled to said optical source and configured to direct an optical signal across said rotary interface; a transmitting optical fiber coupled between said optical source and said transmitting lens; and said second element comprising: a receiving lens opposing said first element across said rotary interface and configured to receive said optical signal from said transmitting lens; an optical-to-electrical O/E converter coupled to said receiving lens and having an optical receiver; and an output electrical lead coupled to said O/E converter; whereby an electrical input received by said first element may be converted into light, said light may be transmitted across said rotary interface to said second element, and said light may be converted into an electrical output by said second element for transmission via said output electrical lead of said second element; characterised in that: the rotary connection is a non-contacting rotary connection at said rotary interface between said first element and said second element; said rotary interface between said first element and said second element comprises an air gap between said transmitting lens of said first element and said receiving lens of said second element; and said first element further comprises a focusing lens coupled between said optical source and said transmitting optical fiber. a housing; a first element supported by said housing; a second element supported by said housing; said first element and said second element configured and arranged such that one of said first or second elements rotates about a central axis (x-x) relative to the other of said first or second elements; a rotary interface between said first element and said second element; said first element comprising: an input electrical lead; an electrical-to-optical E/O converter coupled to said input electrical lead and having an optical source; a transmitting lens coupled to said optical source and configured to direct an optical signal across said rotary interface; a transmitting optical fiber coupled between said optical source and said transmitting lens; and an input electrical lead; an electrical-to-optical E/O converter coupled to said input electrical lead and having an optical source; a transmitting lens coupled to said optical source and configured to direct an optical signal across said rotary interface; a transmitting optical fiber coupled between said optical source and said transmitting lens; and said second element comprising: a receiving lens opposing said first element across said rotary interface and configured to receive said optical signal from said transmitting lens; an optical-to-electrical O/E converter coupled to said receiving lens and having an optical receiver; and an output electrical lead coupled to said O/E converter; a receiving lens opposing said first element across said rotary interface and configured to receive said optical signal from said transmitting lens; an optical-to-electrical O/E converter coupled to said receiving lens and having an optical receiver; and an output electrical lead coupled to said O/E converter; whereby an electrical input received by said first element may be converted into light, said light may be transmitted across said rotary interface to said second element, and said light may be converted into an electrical output by said second element for transmission via said output electrical lead of said second element; characterised in that: the rotary connection is a non-contacting rotary connection at said rotary interface between said first element and said second element; said rotary interface between said first element and said second element comprises an air gap between said transmitting lens of said first element and said receiving lens of said second element; and said first element further comprises a focusing lens coupled between said optical source and said transmitting optical fiber. the rotary connection is a non-contacting rotary connection at said rotary interface between said first element and said second element; said rotary interface between said first element and said second element comprises an air gap between said transmitting lens of said first element and said receiving lens of said second element; and said first element further comprises a focusing lens coupled between said optical source and said transmitting optical fiber.