Optical System Evaluation Using Point Light Source Arrays
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Solution Overview
Problem
Existing optical system evaluation methods face challenges in accurately and efficiently evaluating telecentricity and coma aberration due to the need for precise monitoring of pin-hole positions and the time-consuming process of measuring the entire view field, leading to reduced accuracy and stability issues.
Innovation Solution
An optical system evaluation apparatus and method using a planar array of point light sources, imaging units, and controlled movement to form and image point images, calculating regression expressions for image axis shapes, and fitting characteristic distribution models to evaluate optical characteristics, including telecentricity and coma aberration, with high accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pin-hole is used as a point light source and measured at multiple positions, then the distribution of telecentricity can be evaluated, but the measurement time increases and stability deteriorates
Solution Approach 1:
The invention divides the evaluation into two independent parts: spatial frequency evaluation (using a single pin-hole imaged at multiple Z positions) and telecentricity evaluation (using multiple pin-holes imaged at a single Z position). This segmentation allows parallel processing of different evaluation aspects, reducing total measurement time while maintaining comprehensive coverage of the view field.
Solution Approach 2:
The invention performs preliminary actions by pre-positioning multiple pin-holes in a planar arrangement on the object surface before beginning the measurement sequence. This allows the system to capture telecentricity information across the entire view field in a single Z-position measurement, eliminating the need for time-consuming sequential positioning of individual pin-holes during the measurement process.
2Measurement precision
If the position of pin-hole and enlarged optical system is monitored by measuring means, then image forming position can be calculated, but accuracy is reduced due to measurement instrument limitations
Solution Approach 1:
The invention uses an imaging optical system to create a copied image of the pin-hole on the image surface. By monitoring the position of this copied image through the imaging device, the system eliminates the need for complex triaxial measuring instruments to directly monitor the pin-hole and enlarged optical system positions. The imaging device provides sufficient precision for calculating image forming positions without requiring specialized measurement hardware.
3Measurement precision
If a single pin-hole is imaged at multiple Z positions, then image axis shape can be determined, but the process is time-consuming and stability is reduced
Solution Approach 1:
The invention segments the evaluation process into two independent measurement sequences: one for determining image axis shape (single pin-hole, multiple Z positions) and another for determining telecentricity distribution (multiple pin-holes, single Z position). This segmentation enables the system to complete both evaluations efficiently without the time penalty of sequentially measuring every pin-hole at every position, thereby improving overall productivity while maintaining measurement precision.
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 the rapid and precise evaluation of optical characteristics, particularly telecentricity and coma aberration, across the entire view field with high accuracy, reducing the need for complex and costly measurement instruments.
Implementation Method 1
a point image producing unit that has a plurality of point light sources arranged in a planar form, and forms a point image through the optical system in each of the point light sources
Implementation Method 2
an imaging unit that images a plurality of the point images to produce a point image distribution image
Data Source
AI summary
An apparatus (100) is for evaluating optical characteristics of an optical system (7a) based on an image forming position of a point image formed through the optical system (7a). The apparatus (100) includes a point image producing unit (1 to 4; 4b) that forms a point image through the optical system (7a) in each point light source; an imaging unit (10) that images the point images to produce a point image distribution image; and a moving unit (5) that changes relative distance between the optical system (7a) and the point light source or the imaging unit (10) in an optical axis direction (9). The apparatus (100) also performs processing of detecting an image forming position in each different relative distance of the point image based on image information of the point image distribution images, the processing including calculating a regression expression for the detected image forming positions to obtain a shape parameter of the image axis in each of the point images.