Elizabeth Abraham, Zhaowei Liu. Design, setup, and facilitation of the speckle structured illumination endoscopic system[J]. Opto-Electronic Science, 2025, 4(3): 240022

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- Opto-Electronic Science
- Vol. 4, Issue 3, 240022 (2025)

Fig. 1. Schematic of the SSIE system. (a ) Bench top components. Block 1: laser source of 532 nm; Block 2 (optical components): optical mirrors; Block 3: MM fiber; Block 4: fiber/free space beam splitter; Block 5 (optical components): collimators, optical mirrors and MM fiber; Block 6: step motor, processor, and motor controls. (b ) Endoscope add-on (right to left). Block 7: endoscopic add-on; Block 8: target (colon phantom model).

Fig. 2. Experimental SSIE benchtop setup. (a ) Fiber based setup. (b ) Free space setup. The arrow denotes the pathway and direction of the laser beams traversal. (c ) Step motor programmed to aid in the MM fiber modulation.

Fig. 3. Design and fabrication of the add-on sleeve. (a ) 3D CAD (computer aided design) representation of the add-on sleeve with two fiber holding slits on either ends. (b ) 2D model of the sleeve, cross section of (a) along cutting plane 1, DI and DO are the internal and outer diameters, L is the length of the sleeve, T represents the tilt length and θ represents the tilt angle. The cross sections are identical across cutting planes 1 and 2. (c ) Photograph of the 3D printed sleeve. (d , e ) Schematic of the cross-sectional front end of the endoscope probe without and with the external cover (heat shrink tape) (yellow color slits on either ends represent the fiber slits), respectively. (f ) Schematic of the side view of the endoscopic probe with different layers. The inserted portion refers to the section potentially put into the human body/region of examination and the external portion refers to the rest of the endoscopic probe which is connected to the laser setup of the SSIE (Fig.1 (a, b)). (g ) Photograph of an example Olympus CV-160 endoscopic probe with the sleeve (grey color) which is placed inside an external cover made of heat shrink tape (black) along with the TPU film. (h ) Control knobs of the endoscopic probe. (i ) Picture to depict the bending length of the endoscopic probe with the add-on sleeve (grey color) attached to the endoscope tip (rigid portion: head). (j ) Magnified image of the MM fiber wound around the endoscope insertion tube.

Fig. 4. Phantom construction and feature deposition. (a ) Schematic of feature deposition by drop casting fluorescence dye on sample. (b ) Schematic of feature blood vessel drawing on silicone pads. (c ) Schematic of the cross-sectional view of the colon model with bumps to simulate a realistic colon. (d ) Photograph of the internal cross-sectional view of the colon phantom tunnel simulated with bumps where features drop cast and drawn. (e ) Photograph of the external frame of the colon phantom.

Fig. 5. Fluorescence imaging results with SSIE on colon phantom. (a , b ) Diffraction limited and enhanced SSIE image at imaging distance 2.7 cm. Scale bar: 200 μm. (c ) Ground truth microscopic image of boxed region in (a). (d , e ) Fourier spectra of (a) and (b). (f , g , j , k ) Diffraction limited and enhanced SSIE image at imaging distance 5.7 cm. Scale bar: 2100 μm (large FOV: f, g), Scale bar: 800 μm (medium FOV: j, k). (h , i , l , m ) Fourier spectra of (f, g, j, k). (n , o ) Diffraction limited and enhanced SSIE image at imaging distance 7.2 cm. Scale bar: 500 μm. (p , q ) Fourier spectra of (n) and (o). (r , s ) Diffraction limited and enhanced SSIE image at imaging distance 10 cm. Scale bar: 400 μm. (t , u ) Fourier transforms of (r) and (s).

Fig. 6. Sampling parameter vs enhancement. (a ) Diffraction limited image. (b –h ) Number of frames taken for SSIE processing: 20, 40, 60, 80, 100, 120, 150. Imaging distance: 5.7 cm, Scale bar: 200 μm. (j ) Diffraction limited image. (k –r ) Number of frames taken for SSIE processing: 20, 30, 50, 70, 90, 100, 110, 117, 150. Imaging distance: 4.7 cm, Scale bar: 600 μm. (i ) Enhancement plot of (b–h). (s ) Enhancement plot of (k–r).
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Table 0. Materials used in the add-on for the laboratory prototype.
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Table 0. Expected vs obtained resolution enhancement factor comparison.
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Table 0. Other components used for the SSIE system.
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Table 0. Design and 3D printer parameters of the sleeve.

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