Optical Tomographic Imaging Apparatus Wavelength Separation
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Solution Overview
Problem
The use of optical tomographic imaging apparatuses with low-coherent light sources having wider wavelength bandwidths poses challenges in maintaining accurate wavelength separation characteristics, leading to variations in transmittance and reflectance due to changes in the incident angle of measurement light on dichroic mirrors.
Innovation Solution
The apparatus includes a scanning unit and a second lens disposed to maintain the angle of measurement light incident on the optical path branching unit unchanged, reducing changes in wavelength separation characteristics and improving the accuracy of wavelength separation for both OCT and SLO systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low-coherent light source with a wider wavelength bandwidth is used to improve tomographic image resolution, then the resolution is improved, but the wavelength separation characteristics deteriorate due to variations in transmittance and reflectance caused by changes in incident angle on dichroic mirrors
Solution Approach 1:
The patent changes the geometric parameters of the optical system, specifically the positions of the scanning unit and second lens, to maintain a constant incident angle on the dichroic mirror. This parameter adjustment allows the system to use wider bandwidth light sources while maintaining stable wavelength separation characteristics
Solution Approach 2:
The patent introduces a specific optical configuration with a scanning unit and second lens as intermediary elements between the light source and the dichroic mirror. These intermediaries control the incident angle to remain constant, thereby mediating between the need for wide bandwidth and stable wavelength separation
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
This configuration enhances the accuracy of wavelength separation, reducing variations in transmittance and reflectance, and allows for improved imaging performance even with wider wavelength bandwidths, leading to higher resolution and accuracy in ophthalmologic diagnostics.
Implementation Method 1
separating the wavelengths with use of a wavelength separation unit such as a dichroic mirror
Implementation Method 2
combining return light from the object to be examined irradiated by measurement light via a first lens and reference light corresponding to the measurement light
Implementation Method 3
a scanning unit disposed on an optical path of the measurement light and configured to scan the measurement light on the object to be examined
Data Source
AI summary
An optical tomographic imaging apparatus includes a first lens having a first focal length, a second lens having a second focal length longer that the first focal length, a scanning unit disposed at a focal position of the second lens, and an optical path branching unit disposed between the first and second lenses. An observation optical path located on a transmission optical path of the optical path branching unit, and an optical path of measurement light located on a reflection optical path of the optical path branching unit. The second lens is disposed on the optical path of the measurement light between the first lens and the scanning unit, such that an angle at which the measurement light scanned by the scanning unit is incident on the optical path branching unit is maintained substantially unchanged during scanning.