Question

What is the operating wavelength of He-Ne laser?

(a) 610.8 nm

(b) 622.6 nm

(c) 632.8 nm

(d) 650 nm

This question was addressed to me during a job interview.

My question is taken from PACS (Picture Archiving and Communication System) topic in section Telemedicine Technology of Biomedical Instrumentation

Answer 1

Correct answer is (c) 632.8 nm

To elaborate: The He–Ne laser operating at 632.8 nm wavelength is used. The laser output is coupled into the fibre using a converging lens, which results in an increased power density at the skin surface and thus enables the detection of flow in the more deeply seated veins and arteries.