Optical system and method

An optical system comprising:

• a coherent light source;
• a target;
• optical elements for directing light from the source to the target, said optical elements including at least one diffusing element arranged to reduce a coherence volume of light from the source;
• and
• a deformable mirror system arranged to change optical paths of the light over time, wherein the deformable mirror system comprises:
• a deformable thin plate or film coated to reflect predetermined wavelengths of light;
• actuator means arranged to impart motion to the thin plate or film such that its surface shape is continuously deformed elastically;
• and
• a control system arranged to control the actuator to cause a sequence of motions and surface shape deformations of the thin plate or film to change a speckle pattern formed from coherent light from the coherent light source and reflected from the thin plate or film at the target over a period of time less than the predetermined temporal resolution of an illumination sensor to reduce speckle contrast ratio in the observed illumination.

An optical system comprising:

• a coherent light source;
• optical elements for directing light from the source to a target, said optical elements including at least one diffusing element arranged to reduce a coherence volume of light from the source and a deformable mirror system;
• and
• a control system arranged to control the deformable mirror system to form different speckle patterns over time at the target with a temporal frequency greater than a temporal resolution of an illumination sensor or an eye of an observer to reduce speckle contrast ratio in the observed illumination,
• wherein the deformable mirror system comprises:
• a thin plate or film coated to reflect predetermined wavelengths of light;
• and
• actuator means arranged to impart motion to the thin plate or film such that its surface shape is continuously deformed elastically.