Laser Diode Drive Circuit Stabilizing Output Across Measurement Modes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sample measuring apparatuses face challenges in maintaining stable laser diode output across different measurement modes due to individual variations and temperature changes, requiring complex control mechanisms to suppress mode hopping and adjust light output, which complicates the process.
Innovation Solution
The apparatus incorporates a high-frequency conversion circuit that switches the drive signal between a high and low level in a predetermined cycle, converting the direct-current signal into a high-frequency signal to maintain the laser diode in a multi-mode oscillation state, thereby simplifying the control process and stabilizing output across various measurement modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser diode is continuously supplied with a drive current at a constant level to emit laser light of a single wavelength, then the laser diode operates in a single-mode oscillation state, but temperature changes cause mode hopping and wavelength instability
Solution Approach 1:
The patent applies periodic action by superimposing a high-frequency signal onto the drive current of the laser diode. This causes the laser diode to oscillate between single-mode and multi-mode states periodically, preventing mode hopping and maintaining wavelength stability throughout the measurement period.
Solution Approach 2:
The patent changes the drive current parameter by adding a high-frequency component to the DC drive signal. This parameter modification transforms the laser diode's oscillation behavior from stable single-mode to dynamically switching multi-mode, thereby suppressing mode hopping and stabilizing the emitted wavelength.
2Reliability
If the laser diode is set to a multi-mode oscillation state by superimposing a high-frequency component onto the drive signal, then mode hopping is suppressed, but the control process becomes complicated due to individual differences in laser diode output
Solution Approach 1:
The patent employs feedback control by using an APC (Automatic Power Control) circuit that monitors the actual output of the laser diode and adjusts the drive signal accordingly. This feedback mechanism compensates for individual differences between laser diodes and maintains consistent output levels despite operating in multi-mode oscillation state.
Solution Approach 2:
The APC circuit dynamically adjusts the drive current parameter based on actual output measurements, thereby compensating for individual laser diode variations. This parameter adaptation simplifies the overall control process by automatically compensating for device-specific characteristics rather than requiring manual calibration or complex control algorithms.
3Adaptability or versatility
If the current of the drive signal is adjusted to adapt to different measurement modes (DIFF, RET, PLT), then the laser diode can emit appropriate light levels for each mode, but complicated arithmetic processing by a microcomputer is required
Solution Approach 1:
The patent achieves multi-functionality by designing a universal drive signal generation mechanism that can serve multiple measurement modes (DIFF, RET, PLT) through a single high-frequency conversion circuit. This circuit generates the appropriate high-frequency signal regardless of the measurement mode, eliminating the need for mode-specific control logic and simplifying the overall system architecture.
Solution Approach 2:
The high-frequency conversion circuit acts as an intermediary between the control system and the laser diode. It transforms the DC drive signal into a high-frequency modulated signal that automatically adapts to different measurement modes, thereby decoupling the complexity of mode adaptation from the main control system and simplifying the required arithmetic processing.
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
This solution allows for stable and efficient laser light application to measurement specimens, reducing the need for complex control adjustments and ensuring consistent measurement results across DIFF, RET, and PLT measurement modes.
Implementation Method 1
a laser diode that applies laser light to a measurement specimen prepared from a sample
Implementation Method 2
a high-frequency conversion circuit that generates a potential that switches between a high level and a low level in a predetermined cycle to guide the drive signal outputted from the drive circuit to a second signal path which is different from a first signal path connected to the laser diode in the predetermined cycle, thereby converting the drive signal to be supplied to the laser diode into a high-frequency signal
Implementation Method 3
a detection unit that acquires optical information from a particle in the measurement specimen to which the laser light is applied
Data Source
AI summary
A sample measuring apparatus of an embodiment includes: a laser diode that applies laser light to a measurement specimen prepared from a sample; a detection unit that acquires optical information from a particle in the measurement specimen to which the laser light is applied; a drive circuit that supplies a direct-current drive signal to the laser diode; and a high-frequency conversion circuit that generates a potential that switches between a high level and a low level in a predetermined cycle to guide the drive signal outputted from the drive circuit to a second signal path which is different from a first signal path connected to the laser diode in the predetermined cycle, thereby converting the drive signal to be supplied to the laser diode into a high-frequency signal.