Second harmonic signal generation by low power laser for the use of harmonic microscope

An experiment has been carried out to design a cost effective second harmonic microscope with a low power (2 mW) laser to reduce the possible damage of biological sample. The second order coefficients of different biological materials vary over an enormous range. Hence the harmonic microscope is expected to exhibit enormous contrast in biological specimens which show little or no detail in a conventional microscope. The second harmonic signal (SHS) is detected for a Potassium Dihydrogen Phosphate(KDP) crystal to establish the possibility of mapping through the SHS generated by a 2 mW laser. Finally a biological sample is used to detect SHS by the same method (Choudhury 1977; Yu et al. Biophys J 70:626–636, 1996; Baruah 1999).