Light at wavelengths in the near-
infrared (NIR) region in the second NIR
spectral window from 1,100 nm to 1,350 nm and a new
spectral window from 1,600 nm to 1,870 nm, known as the third NIR optical window, and fourth at 2200 cm−1 are disclosed. Optical attenuation from thin tissue slices of normal and malignant breast and
prostate tissue, and
pig brain were measured in the spectral range from 400 nm to 2,500 nm. Optical images of chicken tissue overlying three black wires were also obtained using the second and third spectral windows. Due to a reduction in scattering and minimal absorption, longer attenuation and clearer images can be seen in the second, third and fourth NIR windows compared to the conventional first NIR window. The second and third spectral windows will have uses in
microscope imaging arteries, bones, breast, cells, cracks, teeth, and blood due to less scattering of light.