Interferometric Probe Motion Detection in Scanning Microscopy
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Solution Overview
Problem
The precision of surface texture measurement in scanning microscopes is limited by the accuracy of measuring probe motion, and simultaneous optical far-field microscopy and scanning microscopy are hindered by light interference issues.
Innovation Solution
A method involving the splitting of an input beam into measurement and reference beams, focused on the reverse focal plane of an objective lens, allowing collimated and reflected beams to interfere, enabling precise interferometric detection of probe motion while minimizing light interference through polarization modification and wavelength selective mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interferometric detection is used to measure probe motion, then measurement precision is improved, but light interference from simultaneous optical microscopy deteriorates
Solution Approach 1:
The optical system is segmented into separate detection paths: one for interferometric probe motion detection and another for optical microscopy. The beam splitter divides the laser beam into measurement and reference beams, while the half-mirror separates the optical paths for near-field detection and far-field microscopy, allowing both functions to operate simultaneously without mutual interference
Solution Approach 2:
A wavelength selective mirror is introduced as an intermediary component to manage light paths. This mirror reflects the laser wavelength used for interferometry while transmitting other wavelengths, enabling the coexistence of interferometric detection and optical microscopy by directing different wavelengths to different detection paths
2Measurement precision
If scanning microscopy is performed with high resolution, then surface texture measurement precision is improved, but scan speed deteriorates
Solution Approach 1:
The measuring probe is designed with multi-functionality, serving both as a scanning probe for high-resolution surface texture measurement and as a reflector for interferometric displacement detection. This integrated design allows simultaneous acquisition of both surface topology and probe position information without requiring separate measurement systems
Solution Approach 2:
The invention merges optical near-field microscopy and optical far-field microscopy into a single instrument. The optical paths are combined through beam splitters and half-mirrors, allowing both high-resolution scanning microscopy and fast optical microscopy to be performed simultaneously on the same sample, thereby overcoming the scan speed limitation of conventional scanning microscopy
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 enhances measurement precision and allows simultaneous optical far-field microscopy and scanning microscopy by reducing light interference, improving the accuracy of surface texture analysis.
Implementation Method 1
splitting of an input beam into measurement and reference beams, focused on the reverse focal plane of an objective lens, allowing collimated and reflected beams to interfere
Implementation Method 2
focused on the reverse focal plane of an objective lens, allowing collimated and reflected beams to interfere
Implementation Method 3
The collimated measurement beam is reflected at the measuring probe, the reflected measurement beam being directed towards the objective lens
Data Source
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AI summary
A method of detecting a movement of a measuring probe provided between an objective lens adapted to image an object plane on a predetermined image plane and the object plane is disclosed. Additionally, a measuring instrument comprising an objective lens and a measuring probe is disclosed. An input beam of light is split into a measurement beam and a reference beam. The measurement beam is focused on a reverse focal plane of the objective lens such that the measurement beam is collimated by the objective lens. The collimated measurement beam is reflected at the measuring probe. The reflected measurement beam is directed towards the objective lens such that the objective lens focuses the reflected measurement beam on the reverse focal plane. The reflected measurement beam is collimated. The collimated reference beam and the reference beam are superimposed to form a superimposed beam and an interference between the reflected measurement beam and the reference beam is detected.