Taking advantage of optical absorption imaging contrast, photoacoustic imaging technology is able to map the volumetric distribution of the optical absorption properties within biological tissues. Unfortunately, traditional piezoceramics-based transducers used in most photoacoustic imaging setups have inadequate frequency response, resulting in both poor depth resolution and inaccurate quantification of the optical absorption information. Instead of the piezoelectric ultrasonic transducer, we develop a graphene-based optical sensor for detecting photoacoustic pressure. The refractive index in the coupling medium is modulated due to photoacoustic pressure perturbation, which creates the variation of the polarization-sensitive optical absorption property of the graphene. As a result, the photoacoustic detection is realized through recording the reflectance intensity difference of polarization light. The graphene-based detector process an estimated noise-equivalentpressure (NEP) sensitivity of ~ 550 Pa over 20-MHz bandwidth with a nearby linear pressure response from 11.0 kPa to 53.0 kPa. Further, a graphene-based photoacoustic microscopy is built, and non-invasively reveals the microvascular anatomy in mouse ears label-freely.
This paper analyses a disparity correction of an advanced multi-sparkle camera system. This system is also called
Cranz-Schardin camera, which a method to achieve extreme high-speed photography. The camera axis in this system
have an angle with principal optical axis, so each image taking by different cameras in system is formed by different
orientation projections of the object, and this process generates parallax among the different cameras. In order to solve
this problem, camera calibration method is setting up after a detailed analysis of this system. A planar calibration is used
as standard reference object in experiment. And image corresponding relationship among different cameras can be built
through learning the position changes of feature points in different cameras. Then, grab pictures from transient
phenomenon which need to be analyzed, and after image processing on these pictures with the image corresponding
relationship, the disparity influence on experiment images in this advanced multi-sparkle camera system would be
In this paper, we proposed a new method, controllable rectangle filter, to improve the resolution of reconstruction in
multi-frame digital holography. In this method, the entire process needs only one hologram with multi-frame digital
holographic interference and the different images' spectrum can be obtained separately without mutual influence.
Therefore the size limiting of the recording objects is reduced and the frame amounts can be increased. Moreover, the
nonessential information of zero-order and the conjugate image can be eliminated well, and the resolution of the
reconstructed images is enhanced. Theoretical analysis and experimental results show that it is a realistic and practical