Fluorescence holography with improved signal-to-noise ratio by near image plane recording

Abstract

Holographic fluorescence imaging is very promising, as it can obtain three-dimensional fluorescence imaging without scanning. However, the current method usually records holograms far from the image plane, with the fluorescence decaying when spreading broadly. Here we show that the signal-to-noise ratio (SNR) of fluorescence holography can be improved by recording the high-contrast interferogram near the image plane. We found that this can be achieved by setting the focal length of the lens for the reference wave (f(2)) close to that for the object wave (f(1)). With experiments, we demonstrate an example of an increase of about 21 times in SNR by changing f(2) from infinity to 226 mm, which is close to f(1) (323 mm).

Violation of the Lagrange invariant in an optical imaging system

“…The FINCH system was initially proposed to overcome the "incoherent property" of partially coherent light [3,4] and was studied extensively [5][6][7][8][9][10]. We find, with intrinsic special characteristics, that this system has the potential to break the Lagrange invariant.…”

“…If the two waves satisfy the requirements of interference [1,6], the interference between wave o 1 and o 2 has a hologram intensity I jo 1 j 2 jo 2 j 2 o 1 o 2 o 1 o 2 , from which the cross term, such as o 1 o 2 , can be obtained using the phase-shifting method [12]. Since o 2 and o 1 are the same, except for the curvature, it can be viewed as that wave o 1 interferes with a duplicate of itself.…”

“…In comparison, the theoretical values of M Hi and M Hα1 calculated using Eqs. (6) and (8) were presented as curves in Fig. 4.…”

Improved axial resolution of FINCH fluorescence microscopy when combined with spinning disk confocal microscopy

“…Self-referenced holographic techniques [1][2][3][4][5] such as FINCH [1,[3][4][5][6][7][8][9][10][11][12] offer advantages over standard coherent holographic techniques, including the lack or requirement for use of a laser in the recording process, suitability for any illumination technique, and, for FINCH and similar techniques, inherent super-resolving capability for objects located away from the focal plane of the entry lens into the system. Thus, since the FINCH concept provides a platform for flexible and adaptable methods with the ability to offer high resolution 3D fluorescent images with little additional difficulty beyond standard imaging techniques, they are increasingly studied as techniques for improving microscopy performance.…”

Selective edge enhancement in three-dimensional vortex imaging with incoherent light

“…To create object correlation records, the achromatic lens (f 150 mm) and the SLM (Hamamatsu, 800 × 600 pixels) were used. Two lenses (f 1 470 mm and f 2 523 mm) were randomly multiplexed on the SLM to realize the dual lens FINCH with spherical signal and reference waves [8,9]. The CCD (Retiga 4000 R) was placed at a distance 495 mm behind the SLM to capture holograms of the object.…”