Thank you for your time and efforts!! I have never investigated LM ICs so deeply, simply because I could get the required results quite easily from these circuits without any hassles… so I won't be able to verify your calculations immediately. I got the Or may be you can refer to the datasheet of the IC itself for studying the various formulas presented in it and compare your results with it…I am sure that will help you to understand the concept with greater details.
Hello Balogh, yes ohms is correct, I think I made a mistake while calculating this resistor. Well, that teaches me a lesson: don't investigate, use! I get always lost in the details.. Great tip, thank you!! Keep up the good work! Hi Amor, you may have to isolate the laser and test it separately with a battery, if you find it OK then you can use it it with another driver circuit. Hello Sir, can i use the above circuit my laser head has 3 pin 20mw nm 3v what will be the value of R3 please!
Hi Amor, the second design would be more appropriate, make sure to fix the current at 6mA and voltage to 3V, for your laser, and the input supply should be around 6V minimum. These are awesome. Love the fact you can turn on laser beam without having to hold the button the entire time and the fact that they are rechargeable.
Plus my kitties love it and the little cute mice that came with it. Thank you! I wonder how the circuit will look like if only I have a 3. Do you have any suggestion to for a 5mW laser driver from a 3.
Hi MA, you can try the transistorized version of the current limiter explained in the following article, and use it for your laser diode:. According to me both the concepts are one and the same.
Both the systems will not allow the current to increase beyond a set threshold, however if the input current tends to drop then both the systems will drop the output current below the intended threshold….
Both the types will not generate their own current to stabilize the output. But its power supply module is stopped working.
I checked this from electrician he told me that power supply is faulty and laser diode is ok. You can adjust the output of the circuit to precisely 3. Respected Swagatam sir ,I want to get the results of photodiode and want to analyze the feedback of the photodiode through oscilloscope, sir will you please help me how to get the feedback circuit for photodiode.
Hello Safi, Photodiode will convert light to DC, which can be easily measured using any small oscilloscope. Your email address will not be published. Notify me via e-mail if anyone answers my comment. You'll also like: 1. Their are kW level drivers available in pulsed and QCW mode versions. Wavelength Electronics has an excellent video describing their current source designs.
It is good information in block diagram form and easy to understand. The information presented in this video will apply to most all commercially available laser diode current sources, differences in function and features will dictate the performance and surely price. Of course you can go much, much deeper in your understanding of laser current sources. A quick search of laser diode current sources on YouTube will result in a multitude of build your own current sources.
It is highly detailed, contains great schematics for those who understand electrical design with mathematically backed design principles and the performance backed up by data and graphs. Here is quick review of the basic package styles and price ranges of constant current and pulsed current sources which are commercially available. These are typically lower power and basic current sources providing 10 mA — mA.
You will find these in your DVD player, bar code scanners, pointers etc. They are available in a wide range of output current ranges, 50 mA — Amps. The only connections to it are the AC input and the output to the laser diode load. These are available in pulsed and CW modes from mA to A or more. You will find these in many optical labs, clean rooms etc.
Laser diode protection, often overlooked, forgotten about or just plain ignored. Well, you can take a chance and just use any current or voltage source, but you will take on the risk of either damaging a very expensive laser diode in development, or risk losing hours of lab work and troubleshooting because of a blown laser.
Diode lasers have a low thermal shock tolerance. Strategies for protection found in most commercially available laser diode current sources include the way the current source is enabled and disabled slow-start circuits , over-current protection current limits , transient protection, cabling etc. There is an excellent Application Note from Newport Corp. Consideration of all protection levels should be a factor in not only found in commercial laser diode current sources but also implemented and followed in the laboratory or product development system.
So, for many applications, highly stable temperature control is required. This answer is most certainly dependent on the application for the diode. In most research applications where you are intending to spend hundreds to several thousands of dollars on a laser diode current source, the most important spec's are: protection from current and voltage overshoots and transients, current noise density and long term stability.
There are many other important features for sure, but you need a constant current source first and foremost to optimize and protect the laser diode for the particular application. One more note about attributes, even though not mentioned in the top three, the current range is of course important. If you do not take into account the extremely low efficiency and the low operating current values with a standard radiator you can slightly increase it by making the radiator significantly larger , then this board has better characteristics in terms of the control amount of current, input and output voltage.
This means that with the maximum laser power in Gcode, you get the minimum laser power and vice versa. The best parameters for this board are given in table 1 Figs. The low 7V voltage is chosen on purpose because the lower the voltage the less the heat release on the radiator. The voltage below 7V strongly reduces the range of the current adjustment. The measurement values are in table 2. As it is seen from the table, the board was overheated at a load resistance of 3.
Table 3 But the board temperature is still too high. As the result of the experiments we managed to set the load current at 3. Table 4 Measurements at a stabilization current of 3. Thus, this board is the most compliant when choosing a power supply source for a lower power laser and for a more powerful laser in an pulse mode. The presented driver has neither settings nor input to control the laser power with a PWM. The driver has a stabilization DC of around mA 0,35A and can be used to feed low-power lasers.
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