Wedge Refractive Index Measurement Without Apex Angle Calibration
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Solution Overview
Problem
Existing methods for determining the refractive index of optical prisms or wedges require knowledge of the apex angle, increasing the measurement effort and complexity.
Innovation Solution
A method and device for determining the refractive index of a wedge-shaped test object without requiring knowledge of the wedge angle, utilizing reflections on the test object's surfaces and a mirror element to calculate the refractive index using detected angles, allowing for simplified and precise measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the apex angle is determined with the aid of a goniometer in preparation for the measurement, then the refractive index can be determined with known angles of incidence and apex, but the measurement effort and complexity increase
Solution Approach 1:
The invention extracts and eliminates the need for goniometer-based apex angle determination from the measurement process. By using an autocollimator to directly measure the angle between reflected light beams from the two wedge surfaces, the method removes the preparatory step of apex angle measurement, thereby simplifying the overall measurement process while maintaining refractive index determination accuracy
Solution Approach 2:
The autocollimator serves multiple functions: it measures both the angle between the wedge surfaces and determines the refractive index, eliminating the need for separate goniometer measurement. This multi-functionality reduces the number of devices and steps required, directly addressing the complexity issue
2Measurement precision
If the apex angle is determined with the aid of a goniometer, then the refractive index can be calculated using Snell's law, but the measurement time increases
Solution Approach 1:
The invention performs the angle measurement between wedge surfaces directly as part of the refractive index determination process, rather than as a separate preparatory step. By measuring the angle between reflected light beams during the same measurement sequence used to determine the refractive index, the method eliminates additional time consumption while maintaining measurement accuracy
3Ease of operation
If reflections on the test object surfaces are used to determine angles, then the refractive index can be calculated without knowing the wedge angle, but additional measurement steps are required
Solution Approach 1:
The invention merges the measurement of the angle between wedge surfaces and the determination of the refractive index into a single measurement sequence. By using the autocollimator to detect reflected light beams from both surfaces and calculate the angle between them, the method combines what could be separate operations into one integrated process, eliminating the need for separate goniometer measurement while maintaining procedural simplicity
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
Enables a simple and time-efficient measurement of the refractive index by calculating it from detected angles, reducing measurement errors, especially for high refractive indices, and eliminating the need for apex angle determination.
Implementation Method 1
detecting a first reflection light beam, a second reflection light beam, and a third reflection light beam, wherein the first reflection light beam represents a light beam reflected on an outer side of the first surface, wherein the second reflection light beam represents a light beam reflected on an inner side of the second surface and wherein the third reflection light beam represents a light beam reflected on a mirror surface
Implementation Method 2
calculating a refractive index using the first angle and the second angle
Data Source
AI summary
The invention relates to a method for determining a refractive index of an optical test object (100), which has a first surface (102) and a second surface (104) arranged at a wedge angle (ω) to the first surface (102), the method comprising the following steps: detecting a first reflection light beam (401), a second reflection light beam (402) and a third reflection light beam (413), wherein the first reflection light beam (401) represents a light beam reflected at the first surface (102) and wherein the second reflection light beam (402) represents a light beam reflected at the second surface (104) and wherein the third reflection light beam (413) represents a light beam reflected at a mirror element (420), determining a first angle (a) between the first reflection light beam (401) and the second reflection light beam (402) and determining a second angle (β) with the aid of the third reflection light beam (413), and calculating (315) the refractive index (n) using the first angle (a) and the second angle (β).