Slit Lamp Illumination Low-Pass Filtering for Pixel Noise Suppression
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Solution Overview
Problem
Existing slit lamp microscopes suffer from non-homogeneous illumination due to the projection of structured light fields, which can cause perceptible periodic modulation and reduce image quality, especially in bright areas.
Innovation Solution
Incorporation of a low-pass filter in the illumination system to attenuate specific spatial frequencies, using techniques such as beam splitters, actuators, or Fourier filtering to generate spatially offset images, thereby reducing the modulation transfer function and enhancing illumination homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a spatial light modulator is introduced into the optical path of a slit lamp microscope to enable optical coherence tomography, then functional versatility is improved, but device complexity increases
Solution Approach 1:
The patent combines the slit lamp microscope and optical coherence tomography systems into a single integrated device. The spatial light modulator is incorporated into the existing optical path of the slit lamp microscope, allowing both slit lamp imaging and OCT functionality to be achieved through one device rather than separate systems, thereby reducing overall device complexity while maintaining functional versatility.
Solution Approach 2:
The integrated system allows the slit lamp microscope to perform multiple functions: traditional slit lamp biomicroscopy and optical coherence tomography. The spatial light modulator enables the same optical path to be used for both imaging modes, making the device universal and eliminating the need for separate specialized equipment.
2Measurement precision
If high-resolution imaging is achieved through optical coherence tomography, then measurement precision is improved, but light loss increases
Solution Approach 1:
The spatial light modulator acts as an intermediary element in the optical path that enables OCT functionality without causing significant light loss. It modulates the light beam to create interference patterns necessary for OCT imaging while maintaining sufficient light intensity to achieve high-resolution cross-sectional images of ocular tissues.
Solution Approach 2:
The spatial light modulator uses periodic modulation of the light beam to generate the interference patterns required for OCT imaging. This periodic action allows for efficient light utilization by creating the necessary optical interference without requiring excessive light intensity, thereby maintaining measurement precision while minimizing energy loss.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The low-pass filter significantly reduces the visibility of illumination inhomogeneities, improving image quality and reducing artifacts, especially in high-magnification views of the eye, by suppressing spatial frequencies associated with the pixel structure of the spatial light modulator.
Implementation Method 1
A spatial light modulator has been introduced into the optical path of the slit lamp microscope to allow optical coherence tomography to be performed
Implementation Method 2
optical coherence tomography has emerged as a useful non-invasive imaging modality
Implementation Method 3
slit lamp microscope spatial light modulator and low-pass filtering
Data Source
Figure 1~9
Figure 2
Figure 3~4
AI summary
The slit lamp microscope comprises a microscope device (8) projecting an object plane (11) into an eyepiece (18) or a camera (16) as well as an illumination device (9) with a spatial light modulator (24). The illumination device comprises a beam splitter (70) acting as a low-pass filter in order to suppress the spatial frequency of the pixels of the light modulator (24) and to generate a more homogeneous illumination. In other embodiments, an actuator (90 – 98) may be used to deflect at least part of the illumination imaging optics (26) for generating a low-pass filtered image of the spatial light modulator (24).