Optical property discrepancies found between healthy and unhealthy skin cells using digital holographic microscopy with three wavelengths

Cancer and other health disorders can be differentiated by changes in cell optical properties such as their refractive index, thickness, and topology (height and width). Here, we employ three wavelengths simultaneously in digital holographic microscopy (3 λ -DHM) to visualize the whole cell topology as 3D images through a numerical reconstruction algorithm applied to a hologram. By identifying the cell state and the changes in its optical properties, it is possible to discern between healthy and unhealthy cells. The simultaneous use of three wavelengths provides a rapid and straightforward quantitative reconstruction of the whole cell without the need for an unwrapping algorithm. This is a benefit over traditional methods, which often require complicated procedures. The performance of the approach was first validated in a known sample, a silicon dioxide thin film, where we were able to corroborate its refractive index with the values reported in the literature. Then the method was applied to fixed skin cells finding a refractive index of 1.3443 for healthy cells and 1.3246 for cells found in tumor tissue. We discuss and highlight differences based on the refractive index to demonstrate that the employed process can provide reliable information to distinguish characteristics between healthy and unhealthy cells.