Abstract
Purpose :
Slit lamps are a mainstay of the ocular anterior segment exam, focusing a thin sheet of light through the cornea and anterior chamber to produce cross-sectional imaging. In anticipation of robotically assisted exams, we developed a lightweight slit lamp module that can be mounted on a robotic arm [1].
[1] M Draelos, et al. Nat Biomed Eng 5, 726-736 (2021)
Methods :
Illumination was achieved using a white LED with a color temperature of 4900 K (Thorlabs). Collimation was done by a condensing lens and aperture. A pair of rectangular micro-lens arrays and a Fourier lens were used to homogenize the light (Fig 1). A linear piezo stage allowed for switching between slit sizes, 10 mm square and 1x10 mm rectangle. We built this system on an optical breadboard for initial characterization to determine the homogeneity and resolution. An Allied Vision 1800 U-2050c (20.2MP) color camera with a 50mm C-Mount lens (Edmund Optics) was used to image the output. The system was further optimized and modeled to meet mass and mechanical requirements for mounting to a robotic arm (Universal Robots UR3). The model of the system to be mounted to the robotic arm was designed to weigh 2.08kg, under the 3kg limit of the arm (Fig 1).
Results :
Constructed on an optical breadboard, the slit lamp system created a homogenized 10 mm square beam (Fig 2A). The uniformity and flatness factor (ISO 13694:2000) of the beam was 16.62% and 75.21% respectively. The spatial resolution of the system was calculated to be 24.81 µm using a resolution target (Fig 2B&C). An image of a 1x10 mm slit was taken on a surgical practice eye with model cornea using the system (Fig 2D).
Conclusions :
Breadboard tests of the initial designed system met performance criteria for mounting on a robot arm. This slit lamp module can be integrated with other ocular diagnostics as part of a robotically based ocular imaging system.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.