CAMBRIDGE MECHATRONICS LIMITED

Broadly speaking, embodiments of the present techniques provide apparatus and methods for generating a three-dimensional (3D) representation of a scene (also known as 3D sensing) using a time-of-flight imaging system. In particular, the present techniques provide an apparatus comprising a time-of-flight imaging camera system that emits illumination having a spatially-nonuniform intensity over a field of view of the sensor that is moved across at least part of the field of view of a sensor using an actuation mechanism.

Embodiments of the present techniques provide apparatus and methods for calibrating the actuation mechanism ( 506 ) of an imaging system ( 500 ) for generating a three-dimensional (3D) representation of a scene ( 508 ). In particular, the present techniques provide for setting the gain of for the actuation mechanism ( 506 ) to a plurality of different gain values, determining a fill-factor for the field of view associated with each of the different gain values and determining a calibrated gain value based on the results. An apparatus ( 500 ) comprises a light source ( 502 ), e.g. a VCSEL array. The light emitted by the light source ( 502 ) passes through one or more optical elements ( 504 ), e.g. lenses, mirrors, diffraction gratings, etc., before being emitted from the apparatus ( 500 ) and projecting onto the scene/object field ( 508 ). The apparatus ( 500 ) comprises a receiver lens and filter system ( 510 ), and a multipixel sensor/detector ( 512 ) for sensing reflected light. One or more of the optical elements ( 504 ) are coupled to an actuation mechanism ( 506 ). The actuation mechanism ( 506 ) moves the optical element ( 504 ) to which it is coupled. The extent by which the optical element ( 504 ) is moved depends on the gain for the actuation mechanism ( 506 ). A control signal is provided to the actuation mechanism ( 506 ). The control signal is amplified by the gain. The amplified signal is applied to the actuation mechanism ( 506 ). Applying the gain calibration techniques to a structured-light 3D scanner may be used to increase the fill-factor.

A method suitable for use by a time-of-flight (TOF) imaging system ( 500 ), wherein the system emits illumination in multiple configurations, each configuration having a different spatially-varying intensity over a field of view of an image sensor ( 512 ), the method comprising: moving an actuation mechanism ( 506 ) to change the illumination via a first sequence of configurations from a first configuration (A) to a final configuration (B); moving the actuation mechanism ( 506 ) to subsequently change the illumination via a second sequence of configurations from the final configuration to the first configuration or a second configuration; and obtaining a set of data from the image sensor ( 512 ) for each of the configurations (A, B) in the first and second sequences, thereby obtaining two sets of data for each configuration that are suitable for producing two depth image frames, wherein the two sets of data corresponding to the final configuration are consecutively obtained from the first and second sequences. Light emitted by light source ( 502 ) passes through a set of one or more optical elements ( 504 ) before being emitted from the TOF system ( 500 ). The set of optical elements ( 504 ) includes a diffractive optical element to produce an optical field, and also includes a shift lens to which the actuation mechanism ( 506 ) is operatively connected. Translational movement of the shift lens in directions perpendicular to the optical axis result in steering of the light. The imaging part includes a receiver lens and/or filter system ( 510 ) and an image a multipixel sensor ( 512 ). The TOF system ( 500 ) also includes a controller ( 500 ).

A time-of-flight sensor system 10 comprising: an illumination source 11 for illuminating a subject 19 to which a time-of-flight is to be measured; an optical system configured to, using an at least one actuator, transition the illumination source 11 between providing spot illumination and flood illumination; and a sensor 12 comprising a sensor surface. The sensor surface is configured to sense light scattered by the subject 19 from the illumination source 12 and to provide data dependent on sensed light. The spot illumination has a spatially non-uniform intensity over the sensor surface, and the optical system is configured to move the spot illumination across at least part of the sensor surface to generate an output frame, wherein the at least one actuator comprises at least one shape memory alloy (SMA) component.

A time-of-flight sensor system ( 100 ) comprising an illumination source ( 102 ), an optical system ( 106 ) and a sensor ( 108 ). The illumination source ( 102 ) illuminates a subject ( 104 ) to which a time-of-flight is to be measured. The optical system ( 106 ) transitions the illumination source ( 102 ) between spot illumination and flood illumination. A sensor ( 108 ) configured to sense light scattered by the subject ( 104 ) from the illumination source ( 102 ) and to provide data dependent on sensed light. The time-of-flight sensor system ( 100 ) is configured to use the data when the illumination is within a range from spot illumination and/or in a range from flood illumination to provide time-of-flight data.

A method suitable for use by a time-of-flight (TOF) imaging system ( 500 ), wherein the system emits illumination in multiple configurations, each configuration having a different spatially-varying intensity over a field of view of an image sensor ( 512 ), the method comprising: moving an actuation mechanism ( 506 ) to change the illumination via a first sequence of configurations from a first configuration (A) to a final configuration (B); moving the actuation mechanism ( 506 ) to subsequently change the illumination via a second sequence of configurations from the final configuration to the first configuration or a second configuration; and obtaining a set of data from the image sensor ( 512 ) for each of the configurations (A, B) in the first and second sequences, thereby obtaining two sets of data for each configuration that are suitable for producing two depth image frames, wherein the two sets of data corresponding to the final configuration are consecutively obtained from the first and second sequences. Light emitted by light source ( 502 ) passes through a set of one or more optical elements ( 504 ) before being emitted from the TOF system ( 500 ). The set of optical elements ( 504 ) includes a diffractive optical element to produce an optical field, and also includes a shift lens to which the actuation mechanism ( 506 ) is operatively connected. Translational movement of the shift lens in directions perpendicular to the optical axis result in steering of the light. The imaging part includes a receiver lens and/or filter system ( 510 ) and an image a multipixel sensor ( 512 ). The TOF system ( 500 ) also includes a controller ( 500 ).

Broadly speaking, embodiments of the present techniques provide apparatus and methods for generating a three-dimensional (3D) representation of a scene (also known as 3D sensing) using a time-of-flight imaging system. In particular, the present techniques provide an apparatus comprising a time-of-flight imaging camera system that emits illumination having a spatially-nonuniform intensity over afield of view of the sensor that is moved across at least part of the field of view of a sensor using an actuation mechanism.