Laser Power Sensor With Apertured Attenuator
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Solution Overview
Problem
Existing laser power sensors face challenges in measuring high-power laser intensities without damaging the light-receiving components due to excessive heat, leading to reduced measurement accuracy and increased costs from using expensive optical components or large, complex designs.
Innovation Solution
A laser power sensor with a light-intensity attenuating member made from a material with zero transmissivity, featuring a plurality of openings that cover at least 50% of the irradiation area, positioned to attenuate the laser beam before it reaches the light-receiving member, which is cooled simultaneously with the sensor to manage thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat capacity of the light-receiving part is increased to prevent damage from excessive heat, then the reliability is improved, but the response speed of the output voltage decreases
Solution Approach 1:
The light-receiving part is divided into multiple regions with different heat capacity characteristics. The first light-receiving region has higher heat capacity to handle high power levels, while the second light-receiving region has lower heat capacity to maintain fast response speed. This segmentation allows each region to serve its specific function without compromising the other.
Solution Approach 2:
Different portions of the light-receiving part are assigned different thermal properties. The first light-receiving region is designed with higher heat capacity for durability, while the second light-receiving region is designed with lower heat capacity for speed. This local differentiation resolves the contradiction between reliability and response speed.
2Temperature
If forced-air-cooling or water-cooling is used to improve cooling capacity, then the temperature control is improved, but the size and cost of the power sensor increase
Solution Approach 1:
The power sensor utilizes its own structural design to achieve passive cooling. The multi-region light-receiving part naturally distributes heat through its differentiated thermal properties, eliminating the need for external cooling systems. This self-service approach reduces both size and cost while maintaining effective temperature control.
3Measurement precision
If expensive optical components like filters or integrating spheres are used to attenuate laser beam intensity, then the measurement accuracy is improved, but the cost increases
Solution Approach 1:
The patent uses a simple, inexpensive absorptive coating on the light-receiving part to attenuate laser intensity, replacing expensive optical components like filters or integrating spheres. This cost-effective approach achieves sufficient measurement accuracy without the high cost of specialized optical components.
Solution Approach 2:
The absorptive coating changes the optical parameters of the light-receiving part by adjusting its light absorption characteristics. This parameter modification enables intensity attenuation without requiring additional expensive optical components, achieving both accuracy and cost-effectiveness.
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 solution allows for precise measurement of laser power with reduced thermal expansion errors and lower costs, extending the sensor's lifespan and reducing the overall size and expense of the power sensor.
Implementation Method 1
the light intensity attenuating member is constituted from a material, a laser transmissivity of which is zero
Implementation Method 2
a light-receiving part for converting energy of an incident laser beam to heat
Implementation Method 3
a thermocouple positioned around a portion of the substrate (or a light-receiving portion) by which the monitor light is directly received, wherein a voltage is generated due to a difference between the temperature of the light-receiving portion and the ambient temperature
Data Source
AI summary
A low-cost laser power sensor having sufficient measurement accuracy with respect to received light intensity of the power sensor. The power sensor has a sensor substrate which receives monitor light, and a filter which attenuates the intensity of the laser beam before being received by the sensor substrate. The filter is constituted from a material having a laser transmissivity equal to zero, and has a plurality of openings within an irradiation range where the monitor light is irradiated. A summation of opening areas of the openings is equal to or more than 50% of the irradiation range. A part of the laser beam, which is irradiated to the filter and passes through the openings, is directly received by the sensor substrate.