A novel imaging method which can acquire high-contrast image of collagen and elastin,two-channel sequential detection imaging based on two-photon excited autofluorescence and second harmonic generation of biological tissues,is presented by using a Zeiss LSM 510 META laser scanning microscopy system.

The high contrast ratio originates from the combination of light scattering from the microdomain polymer gel and absorption from the black dyes.

In order to attain high-contrast and fast noninvasive photoacoustic image,the multi-element phase-controlled technique was combined with the method of increasing the diaphaneity of the tissues with glycerin.

The weak but useful signal limits the OCT imaging speed,detection sensitivity,signal-to-noise ratio and image contrast.

Irradiances reflected from object and backscattered from intervening water are calculated respectively,and the relationship between image contrast and imaging distance is analyzed based on previous computation expressions.

We get the theoretical relationship of visibility distance and image contrast and resolution,and present the formulas for image synthesizing.

When the fingerprint range is 162 mm, the results show that the image contrast of our proposed prism is above 0.