Scan Lens Folded Optical Path for Interferometer Miniaturization
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Solution Overview
Problem
Conventional interferometric measuring devices have a long optical path, which hinders their miniaturization and can lead to measurement errors when using low coherence light sources due to dispersion problems and optical path differences between reference and object beams.
Innovation Solution
A scan lens configuration that includes a lens set, a beam splitter, and a reflector or light transmission device with a light shade, where the light beam is split into a first and second beam, with the second beam being reflected back through a reflector or light transmission device to interfere with the first beam at the beam splitter, thereby shortening the optical path and facilitating device miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional interferometric measuring device uses a long optical path configuration, then the measurement function is achieved, but the device dimension cannot be reduced
Solution Approach 1:
The patent implements a folded optical path design where the optical path is nested within itself by using mirrors to reflect light back through the same optical components. The light beam travels from the light source through the beam splitter to the objective lens, then reflects off mirrors back through the objective lens and beam splitter to the detector, effectively nesting the return path within the outgoing path. This reduces the overall device volume while maintaining the required optical path length for interference measurement
Solution Approach 2:
The patent uses mirrors to change the spatial dimension of the optical path from a straight linear configuration to a folded three-dimensional configuration. By introducing vertical and angular reflections, the optical path is redirected in multiple dimensions, allowing the long optical path to be compacted into a smaller footprint without extending the device in any single direction
2Device complexity
If a low coherence light source is used, then the device can be simplified, but dispersion problems and optical path difference cause measurement errors
Solution Approach 1:
The patent introduces a reference mirror as an intermediary element that creates a reference beam with a known and stable optical path length. This reference beam interferes with the measurement beam from the test object, allowing the system to compensate for optical path differences and dispersion effects. The reference mirror acts as a mediator that enables precise measurement despite using simplified low coherence light sources by providing a stable reference for comparison
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 reduces the size of the interferometric measuring device while minimizing measurement errors by ensuring proper interference patterns for accurate contour and structure analysis of test objects.
Implementation Method 1
a beam splitter (25) adapted to split a light beam (I) passing through the lens set (21) into a first light beam (I1) and a second light beam (I2), wherein the first light beam (I1) passes through the beam splitter (25) and the second light beam (I2) is reflected by the beam splitter (25)
Implementation Method 2
a reflector (23) disposed between the lens set (21) and the beam splitter (25) and adapted to receive the second light beam (I2) that is reflected by the beam splitter (25) and to reflect the received the light beam onto the beam splitter (25)
Implementation Method 3
the first light beam (I1) that is reflected or scattered by the test object (22) and the second light beam (I2) that is reflected by the reflector (23) will interfere with each other at the beam splitter (25)
Data Source
AI summary
A scan lens and an interferometric measuring device using the scan lens are disclosed. The scan lens includes a lens set, a beam splitter, and a reflector disposed between the lens set and the beam splitter. During application the applied light beam passes through the lens set of the interferometric measuring device to fall upon the beam splitter where the light beam that passes through the beam splitter is defined as a first light beam and the light beam that is reflected by the beam splitter is defined as a second light beam. The first light beam is projected onto the test object. The second light beam is projected onto the reflector. The second light beam reflected by the reflector and the first light beam reflected or scattered by the test object will interfere with each other to form interference patterns for measuring the test object.