Display apparatus

A wearable headset incorporating a display apparatus for displaying synthetic scene images responsive to input of image information, the display apparatus comprising:

• a first beam source for providing a first input beam of a first frequency and bandwidth;
• a second beam source for providing a second input beam of a second frequency and bandwidth;
• a display panel arranged such that the display panel is arranged in front of a wearer's eyes at a vertex distance of less than 30 mm for close-to-eye image formation, the display panel containing nonlinear optical (NLO) material that is phase matched to the first and second input beams and to a product beam of a sum frequency that is equal to the sum of the first and second frequencies;
• input beam routing components arranged to introduce the first and second input beams into the display panel so that they traverse the display panel in first and second paths that cross each other in the NLO material in a noncollinear geometry to define an intersection volume where the product beam is generated by sum frequency generation;
• and
• a controller operable responsive to the input of the image information to form the synthetic scene images by amplitude modulating at least one of the first and second input beams and by phase modulating at least one of the first and second input beams to set each of amplitude, wavevector and wavefront radius of curvature of the product beam.

A display apparatus for displaying synthetic scene images responsive to input of image information, the display apparatus comprising:

• a plurality of beam sources with respective frequencies and bandwidths to provide first to third input beam pairs of two input beams, each input beam pair having a pair of frequencies that sum to first to third primary colour frequencies;
• a display panel containing nonlinear optical (NLO) material that is phase matched to the first to third pairs of input beams and to first to third product beams at first to third primary colour frequencies which are equal to the sum of the frequencies of the first to third pairs of input beams;
• input beam routing components arranged to introduce the two input beams of each input beam pair into the display panel so that the input beams of each pair traverse the display panel in first and second paths that cross each other in the NLO material in a noncollinear geometry to define an intersection volume where the product beam for that input beam pair is generated by sum frequency generation;
• an amplitude modulator operable to amplitude modulate at least one beam of each input beam pair;
• a phase modulator operable to phase modulate at least one beam of each input beam pair;
• and
• a controller operable to form colour image frames, each image frame comprising first to third synthetic scene images generated by the first to third input beam pairs respectively, wherein the controller is operable to form each of the first to third synthetic scene images by controlling the amplitude and phase modulators responsive to the input of the image information to set product beam amplitude, product beam wavevector and product beam wavefront radius of curvature.