- Joined
- Jan 2, 2008
- Messages
- 1,513
- Points
- 83
I just got an LPM-1. I love it, however it has no setting for blu-rays. I asked about calibrating it for a 405nm and this is the response I got.
I then asked about the sper2 correction chart and using something like their chart for 405nm diodes and this was the response.
OK, so each sensor is slightly different. What are the options?
EXPENSIVE WAY of doing this is for me so send it back in with a standard and laser and get it done. (I don't want to spend another $100.00 on the meter right now, but if you're intrested, I'm sure he'd do it for you if you have the stuff)
SIMPLE WAY of doing this is find someone with an accurate meter for 405nm and measure their blu-ray with an accurate reading and then a LPM-1 reading in either 473 or 532 and do the division. This would get us all a rough approximation of an accurate correction factor (probably in the 1.75 to 2.6 range)
Another way, I think would work, but requiring more time and patience.
HARD WAY of doing this (but probably more accurate) is to again get someone with a thermopile or something they can accurately measure the 405nm and a LPM-1 to do the same reading as before, but also do a reading at each nm range for that same laser. THEN plot the results. This would give you a graph of the characteristics of that particular sensor. (Albiet a rough graph with only 5 points) Post the results.
Anyone else should be able to take any laser they have and do the same thing matching their graph results against the one that is posted.
The output wouldn't be important for any of the freqs, But the ratio between the different frequencies would be the key factor. Then the results of their graph they could compare against the posted graph and then adjust their correction factor accordingly for a more accurate reading.
If the sensors are similar enough this wouldn't matter much, but if their is a fair degree of change between sensors (say, over 5-10%) then you could improve the accuracy of your particular correction factor by using this.
(The HARD WAY could be done entirely on a LPM without another meter or someone else, but for reference a standard would be nice)
Comments, ideas, help, anyone?
The only comment I have found about LPM-1 and using a 405nm with it is listed below:
The meter could theoretically be calibrated for 405nm. It would be difficult for the following reasons:
-My calibration standard is only spec'd to 430nm, so we would have to locate a standard that can do 405.
-A special software load would be required to add the new wavelength.
-I would need a source, i.e. a laser diode around 20 mW at 405nm.
If you could provide a source and standard, I can do it. The accuracy would be whatever the standard is good for. If you could
provide a source but not a standard, I could probably get it to 10% accuracy with what I've got.
The cost would be $100 for the new software load and time on my bench.
I then asked about the sper2 correction chart and using something like their chart for 405nm diodes and this was the response.
Yes, you could use a correction factor, from the 473 or 532 wavelengths. I don't know what it would be, as I have no references
or standards for that wavelength. It would not be the same as the Sper, as the correction curve is unique to each sensor.
OK, so each sensor is slightly different. What are the options?
EXPENSIVE WAY of doing this is for me so send it back in with a standard and laser and get it done. (I don't want to spend another $100.00 on the meter right now, but if you're intrested, I'm sure he'd do it for you if you have the stuff)
SIMPLE WAY of doing this is find someone with an accurate meter for 405nm and measure their blu-ray with an accurate reading and then a LPM-1 reading in either 473 or 532 and do the division. This would get us all a rough approximation of an accurate correction factor (probably in the 1.75 to 2.6 range)
Another way, I think would work, but requiring more time and patience.
HARD WAY of doing this (but probably more accurate) is to again get someone with a thermopile or something they can accurately measure the 405nm and a LPM-1 to do the same reading as before, but also do a reading at each nm range for that same laser. THEN plot the results. This would give you a graph of the characteristics of that particular sensor. (Albiet a rough graph with only 5 points) Post the results.
Anyone else should be able to take any laser they have and do the same thing matching their graph results against the one that is posted.
The output wouldn't be important for any of the freqs, But the ratio between the different frequencies would be the key factor. Then the results of their graph they could compare against the posted graph and then adjust their correction factor accordingly for a more accurate reading.
If the sensors are similar enough this wouldn't matter much, but if their is a fair degree of change between sensors (say, over 5-10%) then you could improve the accuracy of your particular correction factor by using this.
(The HARD WAY could be done entirely on a LPM without another meter or someone else, but for reference a standard would be nice)
Comments, ideas, help, anyone?
The only comment I have found about LPM-1 and using a 405nm with it is listed below:
When I built my 6 X blu-ray, I took readings with my LPM-1 on the 473nm setting. (no 405 setting). I once read somewhere that you take the 473nm reading, and multiply it by 1.75 to get the conversion to 405nm. After getting a weak conversion at 85mA's, I contacted Hemlock Mike to ask his opinion about the LPM-1 conversion. He told me that multiplying by a factor of 2.6 was about right.
I then took the same reading and multiplied it by 2.6, and the conversion was right in line with Lava's 6 X graph!
Now, I would love to know some other comparisons against the LPM-1 with different meters. I would like to know what others have found for the correct conversion to 405nm with the LPM-1. For now, I am satisfied that Hemlock Mike's recommendation was right in line with Lava's graph.
I would guess that it is between 2.0 and 2.6. But 1.75 is definitely not correct. Way too low on the graph.