Logarithmic Amplifier Offset Control for Wide-Range Light Detection
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Solution Overview
Problem
Existing optical measurement apparatuses face challenges in accurately measuring light intensity across a wide range without distortion, particularly in applications like optical spectrum analyzers, where sensitivity and speed are critical, and they often require complex switching operations and are limited by power supply voltage.
Innovation Solution
An optical measurement apparatus featuring a light receiving element, a logarithmic amplifier with offset resistors and a controller that adjusts offset current to improve measurement sensitivity and speed, allowing for accurate light intensity detection across a wide range without the need for complex switching or power supply limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional linear amplification is used for light intensity measurement, then the circuit structure is simple, but measurement precision deteriorates at low light intensities due to noise and limited dynamic range
Solution Approach 1:
The patent applies parameter changes by switching between linear and logarithmic amplification modes based on the light intensity level. The logarithmic amplifier is used for low light intensity measurements to improve precision, while linear amplification is used for higher intensity levels. This dynamic parameter change allows the system to maintain high measurement precision across a wide dynamic range without requiring a permanently complex circuit structure.
2Adaptability or versatility
If logarithmic amplification is used to improve measurement range, then measurement precision improves, but device complexity increases due to additional switching operations and circuit elements
Solution Approach 1:
The patent implements dynamics by making the amplification mode switchable rather than fixed. The system can dynamically transition between linear and logarithmic amplification based on the measured light intensity level. This dynamic approach allows the apparatus to adapt to different measurement conditions and maintain versatility across a wide range while avoiding the need for permanently complex circuitry that would be required if logarithmic amplification were always active.
3Measurement precision
If high gain amplification is used to improve sensitivity, then measurement precision improves, but speed deteriorates due to increased response time
Solution Approach 1:
The patent resolves this contradiction by changing the amplification parameter based on the measurement conditions. For low light intensity measurements requiring high sensitivity, logarithmic amplification with appropriate gain is applied. For higher intensity measurements where speed is more critical, linear amplification with lower gain is used. This parameter adaptation allows the system to optimize both sensitivity and speed for different operating conditions rather than being constrained by a fixed gain setting.
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 apparatus provides improved light intensity detection performance by accurately measuring light intensity across a wide range, reducing distortion and eliminating the need for complex switching operations, while maintaining high sensitivity and speed.
Implementation Method 1
a light receiving element capable of converting a light intensity of light to be analyzed into an electrical signal
Data Source
AI summary
An optical measurement apparatus having an improved light intensity detection performance is provided. The optical measurement apparatus includes a light receiving element capable of converting a light intensity of light to be analyzed into an electrical signal; an input terminal to which the electrical signal is input; a first amplifier and a nonlinear element configuring a logarithmic amplifier; offset resistors; a switch unit; and a controller. An inverting input terminal of the first amplifier is electrically connected to the input terminal. The offset resistors have different resistance values. The switch unit can switch an offset resistor electrically connected between the voltage source and the input terminal, of the offset resistors. An offset current is input to the input terminal by the offset resistor electrically connected between the voltage source and the input terminal. The controller measures the light intensity based on an output voltage value of the first amplifier.