Collimation Evaluation Device Using Dual Reflection Members
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Solution Overview
Problem
Conventional collimation evaluation devices using shear plates struggle to evaluate the collimation of light with short coherence lengths due to increased optical path difference, which limits sensitivity when trying to improve fringe detection.
Innovation Solution
The device sets an optical path difference between reflected light components to be smaller than the coherence length by using a configuration with a first and second reflection member, where the first reflection surface and second reflection surface are non-parallel, allowing for interference fringe observation and sensitive collimation evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thickness of the shear plate is increased to improve sensitivity, then the sensitivity of collimation evaluation is improved, but the optical path difference increases making it impossible to evaluate light with short coherence length
Solution Approach 1:
The single shear plate is divided into two separate reflection members (first reflection member and second reflection member). Each member has a relatively thin structure, but together they provide the necessary optical path difference control. This segmentation allows the system to maintain sensitivity while keeping the optical path difference within the coherence length of short-pulse laser light.
Solution Approach 2:
A beam splitter is introduced as an intermediary component to divide and recombine light beams between the two reflection members. This intermediary enables precise control of the optical path difference by allowing independent adjustment of each reflection member's position and orientation, thereby maintaining both sensitivity and compatibility with short coherence length light.
2Measurement precision
If the wedge angle between reflection surfaces is decreased to improve sensitivity, then the sensitivity of collimation evaluation is improved, but the interference fringe spacing becomes difficult to control
Solution Approach 1:
The reflection members are designed with adjustable positions and orientations rather than fixed wedge angles. This dynamic configuration allows the interference fringe spacing to be adjusted during operation by changing the relative positions of the reflection members, thereby maintaining both high sensitivity and ease of operation for different measurement conditions.
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 approach enables high-sensitivity collimation evaluation of light with short coherence lengths by optimizing the optical path difference, allowing for accurate assessment of light collimation even when coherence lengths are short.
Implementation Method 1
a first reflection member 10 having a first reflection surface 11 for reflecting a part of incident light L0 and a second reflection surface 12 for reflecting light transmitted through the first reflection surface 11 in the incident light L0; and a second reflection member 20 having a first reflection surface 21 for reflecting a part of light emitted from the first reflection member 10 and a second reflection surface 22 for reflecting light transmitted through the first reflection surface 21 in the light
Implementation Method 2
collimation of the incident light L0 is evaluated on the basis of a direction of interference fringes formed by light L12 reflected on the first reflection surface 11 of the first reflection member 10 and the second reflection surface 22 of the second reflection member 20 and light L21 reflected on the second reflection surface 12 of the first reflection member 10 and the first reflection surface 21 of the second reflection member 20
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
A first reflection member 10, when light transmitted through a second reflection member 20 is incident, reflects a part of the light by a first reflection surface 11, reflects light transmitted through the first reflection surface 11 in the light by a second reflection surface 12, and emits reflected light components in an opposite direction. The second reflection member 20, when light emitted from the first reflection member 10 is incident, reflects a part of the light by a first reflection surface 21, reflects light transmitted through the first reflection surface 21 in the light by a second reflection surface 22, and emits reflected light components. Interference fringes are formed on a screen 30 by light L12 reflected on the first reflection surface 11 of the first reflection member 10 and the second reflection surface 22 of the second reflection member 20 and light L21 reflected on the second reflection surface 12 of the first reflection member 10 and the first reflection surface 21 of the second reflection member 20. Thus, a device and a method that can evaluate collimation of light with high sensitivity, even when a coherence length of the light is short, are realized.