Last years a new non-invasive method has been developed to detect the lesions of breast tissue in both pre- and postmenopause in females. This method is called Frequency Domain Photon Migration (FDPM), which is a laser modulation method, as a sinewave in frequency domain, which depends on the penetration characteristics of laser beam in the breast tissue.Near Infrared lasers used for breast diagnosis due to its ability to penetrate through the multiscattering media that are represented by breast tissue with a multiple thickness reaching to 9.5 cm. It can detect small lesions as well as it can differentiate between the malignant and benign tumors. This method is the best method among the breast diagnostics methods like (X-ray mammography, Computer Tomography (CT scanner), Nuclear Medicine (NM), Ultra Sound (US) and Magnetic Resonance Imaging (MRI)), in that it’s a safe method for diagnosing the tumors and it is easily handled device while the other methods affect the body with side effect on the tissue like a dangerous radiation as in the X-ray mammography, CT scanner and NM. In addition, failure in diagnosing of some lesions like microcalcification in breast as in MRI, some times the ultrasound give fouls diagnosis of the tumor. Moreover, all these methods cannot differentiate between the benign and malignant tumors of the breast tissue. A mathematical model of the laser modulation is used to represent the laser-tissue interaction and calculate the change in amplitude and phase shift of the detected signal. The modulated frequency varies from 1KHz to 1GHz for each chosen thickness from 0.5 to 9.5 cm with 1 cm increment for wavelengths (674, 782, 803, 849, 894 and 956 nm).