Mid-infrared light between 8 to 10 um seems to work with about 84% accuracy, near-infrared light between 1300 and 1900 nm also works, but with lower accuracy:  http://www.opticsinfobase.org/boe/fulltext.cfm?uri=boe-5-7-2397

Mid-infrared light between 8 to 10 um seems to work with about 84% accuracy, near-infrared light between 1300 and 1900 nm also works, but with lower accuracy:  http://www.opticsinfobase.org/boe/fulltext.cfm?uri=boe-5-7-2397

Hi. You should search the absorption bands of glucose instead the blood, in any case you should use a IR laser in order to prevent the cellular damage. Be careful with the laser power. The accuracy depends on the concentration range than you want to detect.

Just another thought: Could you use the optical activity of glucose (rotation of polarization) to measure the concentration independent of absorption features?

Otherwise you have to make sure that no other constituents of blood have absorption bands overlapping with those of glucose.

Waves of mid-infrared range (8 – 10) μ are absorbed glucose molecules that are contained in the interstitial fluid. But this radiation is difficult to obtain by conventional lasers. The lasers require more power and stability that the beam has penetrated through the skin and reach the interstitial fluid. Quantum- cascade laser allows you to choose the frequency for the mid-infrared range, and at the latest achievements in this technology provides enough power and stability to penetrate the skin.

we employed spectrophotometers method to find a suitable way for choosing right wavelengths. Lasers ranging from visible to infrared have been used as the source of light creating Gaussian beam mode. During illumination the output powers of these sources are different but through the experimental processes design, the energy densities are kept identical. 80 samples of blood have taken from 40 diabetic and 40 healthy people. Optical parameters such as absorption, reflection and transmission are considered and investigated, carefully. By analyzing the absorption spectrum given by spectrophotometer after illuminating diabetic samples, it can be seen that the absorption percentage of diabetic blood after the radiation becomes close to the absorption percent of normal index blood and we have found that the 980 nm laser beams have the maximum effects on the change of acute diabetic blood optical parameters.

You can used lasers in the range ( 8 - 12)um which are the best absorption for glucose molecules.

Dear Rajaa, the same answer was given 28 days ago.

Best regards, Leonid 

Mid -IR seems to have better absorbing capacity for glucose unlike near.

Diod laser all range it can be used