This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Ophthalmology
Confocal scanning laser ophthalmoscope uses - 
Select and explain. 
A. Infrared laser, B. Diode laser, C. Excimerlaser, D. YAG laser
B: Diode laser
Answer: B: Diode laser 
Explanation: It is a non- invasive investigation used to receive three- dimensional images of retinal surface in vivo. Commercial name of the device is Heidelberg retina tomograph. Diode laser beam of 670 nm wavelength is used as the light source. Ref: khurana optics and refraction edition 4th , page no. 452