Light source device and image-capturing device

An image-capturing device comprising:

• a light source device comprising:
• a laser light source configured to emit laser light having a peak wavelength included in a wavelength range of light absorbed or reflected by a first region or a second region of an object under study, the laser light source being configured to form a speckle pattern having speckle contrasts that differ between the first region and the second region, and
• a speckle variable device configured to control a coherence of the laser light in response to an external control signal that is input by an operator, wherein:
• the speckle variable device comprises:
• a diffuser disposed in an optical path of the laser light, and
• an actuator configured to move the diffuser to change an incident position of the laser light on the diffuser,
• the actuator is configured to change an observed speckle contrast by changing the coherence of the laser light transmitted through or reflected by the diffuser, in response to the external control signal, and
• the speckle variable device is configured to control the light source device to switch between a first operation mode in which the coherence of the laser light is not reduced and a speckle pattern having a first contrast is formed, and a second operation mode in which the coherence of the laser light is reduced and a speckle pattern having a second contrast is formed, the second contrast being lower than the first contrast;
• an imaging device;
• and
• a controller configured to control an operation of the light source device and an operation of the imaging device, wherein the controller is configured to send the external control signal to the speckle variable device of the light source device to change the speckle contrast in an image obtained by the imaging device;
• wherein:
• the controller is configured to obtain information from the speckle pattern when the light source device is in the first operation mode.