• Opto-Electronic Science
  • Vol. 4, Issue 3, 240022 (2025)
Elizabeth Abraham and Zhaowei Liu*
Author Affiliations
  • Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
  • show less
    DOI: 10.29026/oes.2025.240022 Cite this Article
    Elizabeth Abraham, Zhaowei Liu. Design, setup, and facilitation of the speckle structured illumination endoscopic system[J]. Opto-Electronic Science, 2025, 4(3): 240022 Copy Citation Text show less
    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. 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).
    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. 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.
    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. 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.
    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. 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.
    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. 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).
    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).
    Fig. 6. Sampling parameter vs enhancement. (a) Diffraction limited image. (bh) 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. (kr) 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).
    PartsSpecifications
    Sleeve/Add-on (To hold fiber)Grey Pro (Standard resin: Incept)
    Adhesive (Cyanoacrylate)Loctite 4851 and Super Glue (Henkel, Gorilla)
    Fiber (Multimode)Multimode FG050UGA (Thorlabs) (0.22NA, High-OH, 50 μm core, Lambda: 250–1200 nm, FC/APC termination)
    Medical grade TPU Film (Cover)Polyether TPU (Polyzen)
    Heat shrink (External binding)Ultra-thin wall polyolefin heat shrink tubing (Buy heat shrink)
    Film tape (To secure the fiber)Polyimide film tape
    Table 0. Materials used in the add-on for the laboratory prototype.
    Imaging distance2.7 cm5.7 cm7.2 cm10 cm
    VerticalHorizontalVerticalHorizontalVerticalHorizontalVerticalHorizontal
    Expected4.003.902.832.722.532.412.292.23
    Obtained (Fig.5)3.91 (b)3.79 (b)2.80 (g)2.68 (k)2.60 (g)2.43 (k)2.51 (p)2.39 (p)2.23 (t)2.20 (t)
    Table 0. Expected vs obtained resolution enhancement factor comparison.
    MaterialsSpecifications
    ScopeCV-160 Olympus, Teslong’s borescope endoscope system
    FilterLong pass 580/40 nm (Thorlabs)
    Frame grabberEpiphan VGA2USB device
    ComputerGTX 1080Ti graphics card and a i7-8700K
    Fluorescent dyeRhodamine 6G (10 mg/mL)
    Solution10% glycerol
    MirrorsOptical mirrors (Thorlabs)
    Fiber beam splitter50/50 split ratio (Oz optics)
    Free space beam splitter50/50 split ratio (Thorlabs)
    CollimatorsFiber collimators (Thorlabs)
    LaserContinuous wave, 532 nm, power 200 mW (Newport)Continuous wave, Tunable laser (Thorlabs)
    Optical breadboard24 x 36 inches (Thorlabs)
    Posts, screws, clamps, post holdersThorlabs
    Needle and pipetteStandard laboratory pipetteFine needle tips (0.15 mm: Luter)
    PhantomSilicon material composite pads (MJW surgical and dental)Acrylic pipe rigid round tubes (Meccanixity)Elastic binding bands (Hoyols)Coupler adapter (90°)
    Table 0. Other components used for the SSIE system.
    Design parametersValues
    Internal diameter (DI)10 mm
    Outer diameter (DO)11.4 mm
    Length (L)2 cm
    Tilt length (T)3 mm
    Tilt angle (θ)75° to < 90° (for WD chosen in this study)
    Fiber slit thickness640 μm
    Table 0. Design and 3D printer parameters of the sleeve.
    Elizabeth Abraham, Zhaowei Liu. Design, setup, and facilitation of the speckle structured illumination endoscopic system[J]. Opto-Electronic Science, 2025, 4(3): 240022
    Download Citation