Optical Sensor Wavelength Selection for Hot Object Measurement
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Solution Overview
Problem
Optical measurement methods face challenges when measuring hot objects that emit significant electromagnetic radiation, as increasing illumination intensity to compensate for self-luminance increases energy consumption and may violate power limits, and existing sensors struggle to accurately detect reflected light against self-luminous bodies.
Innovation Solution
Selecting the wavelength of the light beam emitted by the sensor to be below the maximum of the Planckian radiation spectrum of the hot object, allowing for effective detection of reflected light without increasing illumination power, using wavelengths such as less than 450 nm, and employing wavelength-selective elements to filter out unwanted radiation and protect the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the illumination light intensity is increased to compensate for self-luminance of hot objects, then the detectability of reflected light is improved, but the energy consumption of the sensor increases and power limit values may be exceeded
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light to be shorter than the peak wavelength of the object's thermal radiation. This parameter change allows the sensor to operate at lower power levels while maintaining measurement precision, as the shorter wavelength light is less affected by the object's self-luminance in the infrared range
Solution Approach 2:
The patent replaces the conventional approach of increasing light intensity (mechanical/optical power increase) with a spectral selection approach. By substituting the strategy of 'more power' with 'better wavelength selection', the system achieves improved detectability without increasing energy consumption or exceeding power limits
2Measurement precision
If the illumination light intensity is increased to compensate for self-luminance of hot objects, then the detectability of reflected light is improved, but compliance with power limit values prescribed by law may be violated
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light to be shorter than the peak wavelength of the object's thermal radiation. This parameter change ensures compliance with power limit values while maintaining measurement precision, as the shorter wavelength light is less affected by the object's self-luminance
3Length of stationary object
If measurements are taken against self-luminous bodies using conventional optical sensors, then the advantages of optical sensors (large measuring distances with good resolution) are maintained, but the reflected light cannot be sufficiently detected against the self-luminous background
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light to be shorter than the peak wavelength of the object's thermal radiation. This allows maintaining large measuring distances with good resolution while ensuring sufficient detectability of reflected light, as the shorter wavelength light is less overwhelmed by the object's infrared self-luminance
Solution Approach 2:
The patent replaces the conventional approach of increasing light intensity with a spectral selection approach. By substituting 'more power' with 'better wavelength selection', the system maintains the advantages of optical sensors including large measuring distances while improving detectability against self-luminous backgrounds
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 reliable optical distance, position, and profile measurements of hot objects by optimizing the wavelength of the light source relative to the object's radiation spectrum, ensuring sufficient detectability of reflected light without excessive energy consumption or detector saturation, while maintaining the advantages of optical sensors.
Implementation Method 1
Due to its temperature, every hot body emits electromagnetic radiation, the spectrum of which can be described by Planck's radiation spectrum. The Planck radiation spectrum describes the specific radiation over the wavelength of the emitted electromagnetic radiation.
Implementation Method 2
To protect the sensitive detector, the detector can be preceded by a wavelength-selective element. As a result, the electromagnetic radiation of the measurement object can already be masked out quite well.
Data Source
AI summary
The invention relates to an optical sensor for measuring a distance, a position, and/or a profile of a measured object, the measured object emitting electromagnetic radiation due to the temperature of the measured object, and the sensor having a light source for illuminating the surface of the measured object and a detector for detecting the illuminating light reflected at the measurement object, is characterized in regard to the measurability of the optical sensor with respect to bodies that emit electromagnetic radiation in that light generated by the light source has a wavelength below the maximum of the Planck radiation spectrum of the measured object. A corresponding method is specified.