Fast Photothermal Scanning With Pixel-Row Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photothermal scanning methods face challenges in achieving high scanning speeds while maintaining a good signal-to-noise ratio, particularly due to the divergence of the laser beam's point of incidence and thermal emission detection area, which varies with sample movement and thermal radiation development.
Innovation Solution
A photothermal measuring method utilizing a pixel row that spans the entire length of a heated sample location, allowing continuous movement and simultaneous detection of multiple temperatures across multiple light pulses, enhancing resolution and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the laser beam is moved relative to the sample using galvo mirrors to achieve rapid scanning, then the scanning speed is improved, but the point of incidence of the laser beam and the detection area of thermal emission diverge, forming an offset that varies with travel speed
Solution Approach 1:
The patent replaces the mechanical offset compensation approach (moving the field of view optically) with an electronic substitution approach. The sensor's field of view remains stationary while electronic processing compensates for the offset by selecting and processing signals from appropriate sensor elements that correspond to the current laser position, thereby eliminating the need for mechanical or optical realignment during scanning
Solution Approach 2:
The patent implements dynamic electronic adjustment of the active sensor region. As the laser beam moves across the sample, the system dynamically identifies and activates the corresponding sensor elements that are offset from the field of view center by the distance d, allowing the measurement system to adapt in real-time to the changing laser position without physical movement of the sensor or optics
2Measurement precision
If multiple temperatures of a temperature profile are detected over multiple light pulses at a single sample location, then the temperature resolution is improved, but the light beam must remain stationary at each location, forcing stepwise movement and reducing scanning speed
Solution Approach 1:
The patent enables continuous scanning by allowing the laser beam to move continuously across the sample while the sensor continuously detects thermal emission. The stationary field of view with appropriately selected sensor elements captures temperature information along the scan path, eliminating the need to pause at each measurement location and enabling uninterrupted scanning motion
Solution Approach 2:
The patent creates a spatial mapping between the moving laser beam position and the stationary sensor array. By establishing correspondence between laser positions and specific sensor elements (accounting for the offset d), the system effectively copies the temperature profile measurement capability to multiple spatial locations simultaneously through the array, allowing continuous scanning without losing temperature resolution
3Speed
If electronic compensation is used to select relevant pixel areas instead of optical adjustment, then the scanning speed can be increased, but the signal-to-noise ratio still needs improvement
Solution Approach 1:
The patent transitions from one-dimensional point measurement to two-dimensional area measurement by utilizing multiple sensor elements arranged in rows and columns. The measurement area extends beyond the field of view center along the scan direction, capturing thermal emission from multiple spatial locations simultaneously. This dimensional expansion provides redundant measurement data that can be processed to improve signal-to-noise ratio while maintaining high scanning speeds
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 high-throughput photothermal measurements with continuous scanning speeds up to 500 mm/s and improved signal-to-noise ratio, allowing for precise measurement of layer thicknesses on elongated samples.
Implementation Method 1
a heating element in the form of a laser is used to heat the sample
Implementation Method 2
The sensor comprises an infrared pixel matrix and a lens that images the thermal radiation of the sample onto the pixel matrix
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
In a photothermal measuring method, a photothermal measuring device (1, 6, 16) comprises a sensor (1) for detecting thermal radiation, wherein the sensor (1) has a sensor element (2) with a plurality of pixels (2a, 2b, 2c, 2d). At least two of the pixels (2a, 2b, 2c, 2d) form a pixel row (3) of the sensor element (2), wherein a sample (4) is imaged on the sensor element (2) on the sample (4) and a field of view (5) of the sensor element (2) of a surface of the sample (4) is defined. A first field of view region (5a) on the sample (4) is assigned to a first pixel (2a) of the pixel row (3), and a second field of view region (5b) on the sample (4) is assigned to a second pixel (2b). A heating element (6) generates a heat field (7) on the sample (4) and heats at least one sample location (8) or a sample surface of the sample (4). The heated sample location (8) is moved relative to and through the field of view (5) or through the first.Field of view (5a) and then relatively moved through the second field of view (5b). The first pixel (2a) is read out and provides first read data (L1) of the heated sample location (8) from the first field of view (5a). The second pixel (2b) is read out and provides second read data (L2) of the heated sample location (8) from the second field of view (5), with the second pixel (2b) being read out after the first pixel (2a).