Control device and medical observation system

A medical observation system comprising:

• an imaging device having an autofocus function and configured to generate an image signal by capturing an observation target;
• and
• a control device configured to process an image signal generated by the imaging device, the control device including
• an acquisition circuit configured to acquire first and second image signals generated by the imaging device by capturing an observation target irradiated with first light and second light having different wavelength bands, respectively;
• a signal processor configured to detect detection information of the first and second image signals, and
• a control circuit configured to
• calculate a first focal length based on the detection information of the first image signal,
• calculate a second focal length based on the detection information of the second image signal,
• determine a difference between the first focal length and the second focal length;
• and
• set a focal length of the imaging device to capture the observation target irradiated with the second light to either the first or second focal length at least based on the difference.

A control circuit to control a focal length of an imaging device having an autofocus function that images an observation target irradiated with first light and second light having different wavelength bands, respectively, the control circuit configured to:

• calculate a first focal length based on a first image signal of the observation target irradiated with the first light,
• calculate a second focal length based on a second image signal of the observation target irradiated with the second light,
• determine a difference between the first focal length and the second focal length;
• and
• set a focal length of the imaging device to capture the observation target irradiated with the second light to either the first or second focal length at least based on the difference.