Optical Path Difference Generating Member for Accurate Focus Detection
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Solution Overview
Problem
Conventional image acquisition devices face challenges in ensuring sufficient light for imaging while accurately detecting the focal position, as splitting light with a half prism can lead to reduced detection accuracy and inadequate light for imaging.
Innovation Solution
An image acquisition device and method that utilize an optical path difference generating member with tilted faces and a light reduction portion to create an optical path difference without splitting light in the second optical path for focus control, ensuring enough light for imaging while allowing accurate focal position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light from the specimen is split by a half prism to be received by a photoelectric conversion element, then focus detection can be performed, but the quantity of light on the photoelectric conversion element is insufficient, resulting in degradation of detection accuracy
Solution Approach 1:
The imaging surface is divided into a first imaging region for receiving light from the first optical path and a second imaging region for receiving light from the second optical path. This segmentation allows separate optimization of light allocation for imaging and focus detection, resolving the contradiction between sufficient light quantity and detection accuracy.
Solution Approach 2:
A light reduction portion is introduced as an intermediary element in the second optical path to control and reduce the quantity of light reaching the second imaging region. This intermediary component enables precise regulation of light distribution, ensuring that focus detection receives adequate light while preventing excessive light from compromising the imaging quality in the first optical path.
2Measurement precision
If the quantity of light is increased for the light for detection of the focal position, then focus detection accuracy is improved, but the quantity of light for imaging of the specimen is reduced
Solution Approach 1:
By segmenting the imaging surface into distinct first and second imaging regions that receive light from separate optical paths, the system enables independent light quantity optimization for each function. The first imaging region maintains sufficient light for high-quality specimen imaging, while the second imaging region receives controlled light for accurate focus detection.
Solution Approach 2:
The light reduction portion serves as a mediator that precisely controls the light quantity in the second optical path dedicated to focus detection. This intermediary element ensures that the second imaging region receives an optimal, reduced quantity of light sufficient for accurate focal position detection without compromising the light availability for the primary imaging function.
3Illumination intensity
If an optical path difference generating member with tilted faces is used to create optical path difference without splitting light, then sufficient light for imaging is ensured, but additional optical components are introduced
Solution Approach 1:
The optical path difference generating member combines multiple functions into a single component: it creates the necessary optical path difference for focus detection while simultaneously maintaining sufficient light quantity for imaging. This merging of functions reduces the need for additional light-splitting components and simplifies the overall optical system architecture.
Solution Approach 2:
The optical path difference generating member with tilted faces serves multiple purposes: it generates optical path difference for focus detection and preserves adequate light quantity for imaging. This multi-functional component eliminates the need for separate light-splitting mechanisms, thereby reducing device complexity while achieving the desired optical performance.
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 ensures accurate focal position detection while maintaining sufficient light for imaging, enabling bidirectional scanning and expanding the focus difference between front and back focus, thus improving imaging accuracy.
Implementation Method 1
an optical path difference generating member having a first face and a second face tilted relative to a plane orthogonal to an optical axis of the second optical path and adapted to generate an optical path difference in the second optical image
Implementation Method 2
a light reduction portion for reducing light reaching the imaging surface is provided between the first face and the second face
Data Source
AI summary
In an image acquisition device M, an optical path length difference in a second optical image can be formed by arrangement of an optical path difference generating member 21, without need for splitting light in a second optical path L2 for focus control. Therefore, it reduces the quantity of light into the second optical path L2 necessary for acquisition of information of focal position while ensuring the quantity of light enough for execution of imaging by a first imaging device 18. Furthermore, in this image acquisition device M, a light reduction portion 28 for reducing light reaching an imaging surface 20a of a second imaging device 20 is provided between a first face 26 and a second face 27 of the optical path difference generating member 21. This light reduction portion 28 can narrow a light superimposed region 29 on the imaging surface 20a of the second imaging device 20, which allows control of the focal position to a sample S to be accurately carried out.