Laser Diode Driver Circuit for Discrete Pulse Shaping in Ophthalmology
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Solution Overview
Problem
Current ophthalmological laser treatment devices face challenges in generating precisely shaped laser pulses with short durations, such as those required for Selective Retina Therapy, due to the complexity and cost of existing systems, which often necessitate multiple devices for different treatment methods.
Innovation Solution
A driver circuit with multiple parallel current branches and switchable resistors, controlled by a microcontroller or digital electronics, allows for the generation of discrete and reproducible laser pulses by adjusting the total resistance in discrete stages, enabling the creation of precisely shaped pulses without the need for analog or digital controllers, and can produce both short and long pulses efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple devices are used for different treatment methods, then treatment versatility is improved, but device complexity and cost increase
Solution Approach 1:
The driver circuit is designed with multiple parallel current branches (at least two) that can be independently controlled through digital electronics. Each branch contains switchable resistors that allow the circuit to generate different current profiles and pulse shapes. This multi-functional design enables a single device to perform various ophthalmic treatments (such as selective retinal therapy, photocoagulation, and other laser treatments) by selectively activating different branches and adjusting resistance values, thereby eliminating the need for multiple separate devices while maintaining treatment versatility.
Solution Approach 2:
The driver circuit is divided into multiple parallel current branches, with each branch containing switchable resistors. This segmentation allows independent control of each branch through digital electronics, enabling flexible combination of branches to generate different current profiles. By dividing the circuit into manageable segments that can be independently activated or deactivated, the system achieves high adaptability for different treatment methods while keeping the overall device structure organized and controllable.
2Manufacturing precision
If analog or digital controllers are used for continuous resistance control, then light power control precision is improved, but device complexity and cost increase
Solution Approach 1:
Instead of using a continuous analog controller, the resistance control is segmented into discrete steps by providing multiple parallel current branches with switchable resistors. Each branch contributes a specific resistance value, and by selectively activating combinations of these branches, the total resistance can be adjusted in discrete steps. This segmented approach achieves precise light power control through digital switching of individual branches, replacing complex analog controllers with simpler digital logic while maintaining sufficient precision for ophthalmic treatments.
Solution Approach 2:
The circuit employs dynamic switching of resistors in parallel current branches to achieve variable resistance control. Rather than using a static or continuously adjustable analog controller, the system dynamically reconfigures the resistance network by turning specific branches on or off based on digital control signals. This dynamic reconfiguration allows precise adjustment of light power output through discrete resistance steps, simplifying the control architecture while maintaining effectiveness.
3Manufacturing precision
If short laser pulses are generated, then treatment precision is improved, but pulse shaping control becomes more difficult
Solution Approach 1:
The driver circuit uses multiple parallel current branches with switchable resistors to segment the current delivery path. By independently controlling the switching timing and resistance values of each branch, the circuit can generate precisely shaped short laser pulses. The segmented structure allows different parts of the pulse waveform (rise time, peak duration, fall time) to be controlled by different branch combinations, achieving high treatment precision for short pulses without requiring overly complex external pulse shaping electronics.
Solution Approach 2:
The circuit prepares multiple current branches with pre-configured resistance values that can be rapidly switched to generate the desired pulse shape. By having the resistance network pre-configured in discrete steps through the parallel branch structure, the system can quickly transition between different resistance states to create precisely shaped short pulses when triggered, eliminating the need for complex real-time adjustment mechanisms during pulse generation.
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 simplifies the control of laser power, allows for precise generation of laser pulses, reduces the need for multiple devices, and enhances treatment efficiency with minimal tissue damage, making it possible to construct a more cost-effective and efficient ophthalmological laser treatment device capable of various treatment methods.
Implementation Method 1
a circuit (2) comprising a voltage source (3), a light source (5), a series resistor and a switch (S), wherein the circuit (2) is branched into at least two parallel current paths (21, 22), in each current path (21, 22) there is a parallel resistor (R1, R2) and a switch (S1, S2) for switching on or off the parallel resistor (R1, R2)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a driver circuit (1) for generating a current flow through a light source (5), in particular a laser diode (LD), to a method for operating the driver circuit (1), and to an opthalmological laser treatment device comprising such a driver circuit (1). A voltage source (3), the light source (5), a series resistor and a switch are arranged in an electric circuit (2). To generate a series resistance which can be controlled or regulated in discrete stages for the light source (5), the electric circuit (2) is branched into at least two parallel branch circuits (21,..., 2N), and there is at least one connectable parallel resistor (R1,...,RN) in each branch circuit (21,..., 2N).