A system, comprising: a first optical assembly, OA, which is coupled with a first eyepiece of a stereoscopic microscope, SM,, the first OA comprising: (i) a first light source (110, 112), configured to direct a first emitted light beam, ELB, (101, 102) through the SM toward an organ of a patient, and (ii) a first image sensor, configured to sense a first reflected light beam, RLB, which is reflected from the organ through the SM, and to produce a first signal indicative of the first RLB; a second OA, which is coupled with a second eyepiece of the SM, the second OA comprising: (i) a second light source (110, 112), configured to direct a second ELB (101, 102) through the SM toward the organ, and (ii) a second image sensor, configured to sense a second RLB, which is reflected from the organ through the SM, and to produce a second signal indicative of the second RLB; and a processor, which is configured to: control the first and second OAs (25A, 25B) to alternately: (i) direct the first ELB (101, 102) and sense the first RLB at first time intervals, and (ii) direct the second ELB (101, 102) and sense the second RLB at second different time intervals; and alternately: (i) display on a first display, during the first time intervals, first images based on the first signal, and (ii) display on a second display, during the second time intervals, second images based on the second signal. a first optical assembly, OA, which is coupled with a first eyepiece of a stereoscopic microscope, SM,, the first OA comprising: (i) a first light source (110, 112), configured to direct a first emitted light beam, ELB, (101, 102) through the SM toward an organ of a patient, and (ii) a first image sensor, configured to sense a first reflected light beam, RLB, which is reflected from the organ through the SM, and to produce a first signal indicative of the first RLB; a second OA, which is coupled with a second eyepiece of the SM, the second OA comprising: (i) a second light source (110, 112), configured to direct a second ELB (101, 102) through the SM toward the organ, and (ii) a second image sensor, configured to sense a second RLB, which is reflected from the organ through the SM, and to produce a second signal indicative of the second RLB; and a processor, which is configured to: control the first and second OAs (25A, 25B) to alternately: (i) direct the first ELB (101, 102) and sense the first RLB at first time intervals, and (ii) direct the second ELB (101, 102) and sense the second RLB at second different time intervals; and alternately: (i) display on a first display, during the first time intervals, first images based on the first signal, and (ii) display on a second display, during the second time intervals, second images based on the second signal. control the first and second OAs (25A, 25B) to alternately: (i) direct the first ELB (101, 102) and sense the first RLB at first time intervals, and (ii) direct the second ELB (101, 102) and sense the second RLB at second different time intervals; and alternately: (i) display on a first display, during the first time intervals, first images based on the first signal, and (ii) display on a second display, during the second time intervals, second images based on the second signal.