LITV Laser Radiation Detector Using Glancing Angle Deposition
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Solution Overview
Problem
Current laser radiation detectors face challenges such as slow response times, large size, and limitations in measuring continuous wave (CW) laser radiation, particularly due to the need for complex alloys and specific substrate configurations in sensors using the laser-induced transverse voltage (LITV) effect.
Innovation Solution
A detector based on the LITV effect with a highly multi-crystalline active layer, fabricated using glancing angle deposition (GLAD) on a ceramic or metallic substrate without the need for seed buffer layers or specific substrate orientations, allowing for a robust and efficient measurement of high energy pulses with adaptable response times and damage thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors using the LITV effect with complex alloys and specific substrate configurations are used, then measurement precision is improved, but device complexity increases and ease of manufacture deteriorates
Solution Approach 1:
The patent changes the substrate parameter from requiring specific crystal orientations to using polycrystalline substrates without orientation requirements. This parameter change maintains the LITV effect functionality while eliminating the need for complex substrate preparation and alignment procedures, thereby reducing device complexity without sacrificing measurement precision
Solution Approach 2:
The patent replaces expensive complex alloys with simpler, more readily available materials that can be deposited using standard techniques. This substitution maintains adequate measurement precision while significantly reducing manufacturing complexity and cost
2Reliability
If radial thermopiles with large heat-sink are used, then reliability is improved, but volume increases and response time worsens
Solution Approach 1:
The patent replaces the mechanical thermal conduction path through large heat-sinks with the LITV effect, which generates voltage directly in response to thermal gradients. This substitution eliminates the need for bulky heat-sink structures while maintaining reliable measurement capability, thereby reducing volume without compromising reliability
3Volume of moving object
If axial thermopiles with multiple thermocouples are used, then volume is reduced, but manufacturing precision requirements increase and response time remains limited
Solution Approach 1:
The patent extracts the need for multiple precisely-aligned thermocouples by utilizing the LITV effect in a single thin film layer. This extraction maintains compact volume while eliminating complex manufacturing precision requirements associated with assembling multiple thermocouple elements
4Measurement precision
If pyroelectric sensors are used, then sensitivity is improved and response time for pulsed radiation is reduced, but ability to measure continuous wave radiation deteriorates
Solution Approach 1:
The patent creates a universal detector based on the LITV effect that can measure both pulsed and continuous wave laser radiation. The thin film structure responds to thermal gradients generated by both pulsed and CW radiation, providing adaptability across different radiation types while maintaining high sensitivity through the efficient LITV transduction mechanism
5Productivity
If response time is reduced to nanosecond range in LITV sensors, then productivity is improved, but ability to measure high energy pulses deteriorates due to damage threshold limitations
Solution Approach 1:
The patent optimizes the thickness parameter of the thin film to balance response time and damage threshold. By carefully selecting the film thickness, the detector achieves sufficiently fast response for high productivity while maintaining adequate damage threshold to reliably measure high energy laser pulses without destruction
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
The detector achieves a response time of tens of milliseconds, enabling digitalization of output signals without expensive electronics, and can measure CW to pulsed laser radiation across a broad range of power densities and frequencies, with a high damage threshold and simplified manufacturing process.
Implementation Method 1
Sensors using the laser induced transverse voltage (LITV) effect also transduce a thermal gradient into an electric signal. Thin films of suitable materials (e.g. Bi, Bi 2 Te 3 , al:ZnO, Sb), deposited with a slant angle between the evaporation source and the substrate are known to show a transverse thermoelectric response to laser-irradiation.
Implementation Method 2
Thin films of suitable materials (e.g. Bi, Bi 2 Te 3 , al:ZnO, Sb), deposited with a slant angle between the evaporation source and the substrate
Data Source
Figure 1a~1c
Figure 2~3
AI summary
A detector of electromagnetic radiation (RL) is described. The detector comprises: -an oriented polycrystalline layer (2) of thermoelectric material, -a substrate (1) superimposed on the top surface of the oriented polycrystalline layer so that the back surface (10) is in contact with the oriented polycrystalline layer, -first and second electrodes spaced the one from the other and in electrical contact with the oriented polycrystalline layer. The substrate comprises at least one ceramic layer and the oriented polycrystalline layer has a crystal orientation at an angle comprised between 30 degrees and 5 degrees relative to a normal to the top surface of the substrate.