Which meter would you trust more as a reference? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 23 Old 05-04-2017, 12:15 PM - Thread Starter
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Which meter would you trust more as a reference?

I recently purchased a used i1Pro off ebay to use as a reference with my i1 Display Pro meter that I've been using to calibrate my displays. Its last certification was in 2009. I was also recently able to borrow a new ColorMunki Photo, and the readings it gave were a little different - not much, but I'm wondering which meter is likely to be more accurate - a 9 year old i1Pro or a brand new ColorMunki Photo?

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post #2 of 23 Old 05-04-2017, 01:06 PM
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It was once said to me, "A man who has two watches really never knows what time it is".

If in doubt send the i1Pro in to be re-certified. SpectraCal offers this as a service.
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post #3 of 23 Old 05-04-2017, 02:03 PM - Thread Starter
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Originally Posted by randal_r View Post
It was once said to me, "A man who has two watches really never knows what time it is".
Yup, I know what you mean.

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post #4 of 23 Old 05-05-2017, 12:33 AM
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Everything has error, even the best has some, just less than every man(person) devices.

I advise researching what error means, especially accuracy and precision for measurement devices.
Then look at the specs of your devices and see how they compare with that knowledge.

With that, the key thing to understand is when comparing measurements is the devices ability to measure a point and what error is around that point. If comparing another device with the same point and the result is different within reason, the actual measurement plus the error for each device should be taken into account then if they overlap it is more or less the same measurement. This is typically ignored in discussions about how accurate any device is, typically the argument is/are the device is poor below this level or this device is better or worse than another relative to some set of data. The problem with this is the noise and error in displays, sources and video chain all contains cumulative error.

This is one of the key reasons professionals and advanced enthusiasts purchase higher quality and more expensive devices, basically to limit error of measurements so that the display is a denominator.

My I1pro is reasonably close to my Jeti1211 in xy depending on the source light, but average in Y. But if all I had was the i1pro with my i1displaypro I'd still be comfortable with performance.

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post #5 of 23 Old 05-05-2017, 04:48 AM
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Quote:
Originally Posted by randal_r View Post
It was once said to me, "A man who has two watches really never knows what time it is".

If in doubt send the i1Pro in to be re-certified. SpectraCal offers this as a service.
Hi Randal,

SpectraCAL is not offering re-certification of i1PRO's anymore.

http://calman.spectracal.com/store/p...ification.html

http://calman.spectracal.com/lab-services.html

We have discussed the quality of the service at past here: http://calman.spectracal.com/lab-services.html

...while SC president claiming that checking about +1000 i1PRO every year, none failed to have higher deviations from +-0.001 xy using a Minolta CS-2000 as a reference: X-Rite EyeOne Pro / I1 Pro Recertification Now Available from SpectraCal!

...the same time i1PRO2 measured from Klein Instruments NIST labs (only tracking comparison, since they are not providing re-certification of i1PRO's there), they found measuring a nearly brand new i1PRO2 of a forum member here (SillySally), using 4 different displays, differencies of max 0.0067 on x/y and 8.93% Y. They did this for free since SillySally was already a Klein K-10A customer and finally he decided to sell his i1PRO2 and buy a JETI 1211.

Quote:
Originally Posted by sigma957 View Post
I recently purchased a used i1Pro off ebay to use as a reference with my i1 Display Pro meter that I've been using to calibrate my displays. Its last certification was in 2009. I was also recently able to borrow a new ColorMunki Photo, and the readings it gave were a little different - not much, but I'm wondering which meter is likely to be more accurate - a 9 year old i1Pro or a brand new ColorMunki Photo?
Hi, the ColorMunki Photo is not coming (when someone is buying it brand-new) with any kind of performance proof (certification from X-Rite) so it may have larger unit-to-unit variation for it's accuracy performance.

i1PRO's are coming with proof of performance which is valid for one year (for safery reasons) but because electronics/optics used are lower grade (than one used from reference meters) they are affected more in physical aging...also when you buy a used meter, it's unknown if it's been dropped or if it's holographic diffraction grating or the sensitivity of the diodes has been degraded, or if the dust internally to the meter optics is reducing it's sensitivity. The indicator of the working hours of the internal lamp i1PRO has (using X-Rite's i1Diagnostic software) doesn't say anything when you are measuring a display (using its Emission Mode) because the internal lamp is not used when you are measuring a display, it's used to illuminate the object when you are measuring the reflective light of a printed paper for example; using the meter at its Reflectance mode.

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post #6 of 23 Old 05-05-2017, 06:22 AM
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Thanks Ted,

I haven't really keep up on the services that companies are offering. After reading your posting, I googled "X-Rite" for repairs & recertification and they do offer the service (worldwide).

You mentioned the diagnostics software from X-Rite. I agree with the scenario of operations that you defined whole heartedly. A question comes to mind, is there really a difference in the function between reflective mode vs emission mode? Theoretically, the internal functions of the optical grating and so on, should be identical with the exception of the usage of the internal light source. If this weren't so then the i1Pros would have two internal mechanisms, one for reflective mode and another for emission mode. I once had an i1pro a number of years ago that took a tragic fall. Needless to say I had to replaced it. Since the damaged unit was trash and I would never think of deceiving anyone buy selling it, I tore it apart to see what was inside. As we all know only one optical grating.

I am sure that you would agree with me that everything is in a state of decay. Even if you keep it in a box on a shelf and never use it, there is still a level of decay occurring. Maybe I am wrong but the individual inquiring has the appearance of being a hobbyist and in many cases these individuals will not likely spend $10000 or more for a spectro like you and I would. So the usage of a i1Pro meets the need of this individual so repairing it is not out of the question.

I am not disagreeing with you regarding the testing of the probes by the two companies but my nature is to desire a third evaluation from another source to confirm a conclusive out come. It is said that everything has a error factor. Even a CS-1000 has an error factor when comparing it to the CS-2000.

I would like to thank you for the great info. I try and follow your postings as there is always something new to learn or a different perspective is given. You haven't disappointed me yet. Have a good day.
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post #7 of 23 Old 05-05-2017, 09:11 AM
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I'd take the i1pro everytime. I am convinced these drift very little.

I have a rev A that is around 14-15 years old, and rev b that is 10-11 years. Both have been heavily used in printer profiling with x-rite IO robotic arm. They still more or less measure the same as my i1pro2.

In fact, from these "surplus" i1pros, I have made myself a "portable" calibration kit with i1pro + i1disp pro + hdmi output+cables. Fits very comfortably inside a little airtight plastic case and is perfect for somewhat less critical calibrations (family/friends/etc), and very travel friendly to boot. Using HDMI output for calibration is as always real hassle, but apart from that, using i1pro to profile the i1disp pro is a great combination.

True, with a used i1pro you cannot know for sure if it has sustained any damage. But really, if you compare the measurements with a i1disp pro, and the readings are in the same ballpark as the colorimeter, then chances are that it's fine.
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post #8 of 23 Old 05-05-2017, 10:34 AM - Thread Starter
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Thanks for the input. In reality, either meter is probably accurate enough for my purposes. As a Home DiY calibrator / Hobbyist, re-certifying a meter is prohibitively expensive. The point of buying a used one is to get a high quality meter for not too much money. You just take the risk of not knowing how it's been treated.

When I compare readings from the 2 meters, they're actually very close. The x and y numbers are almost identical, which makes me confident that they're probably pretty accurate. The only real difference is that the ColorMunki "Y" readings tend to be about 2-4% lower than the i1Pro. I think I'll stick with the i1Pro because it just feels like a higher quality device.

Interestingly, readings from my i1 Display Pro are also pretty close to the i1Pro. In fact, on my Sony LCD their readings are almost identical. The correction matrix I generated for the LCD was very close to having no correction at all. On my LG OLED, the difference was more significant.

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post #9 of 23 Old 05-06-2017, 08:46 AM
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Quote:
Originally Posted by sigma957 View Post
Thanks for the input. In reality, either meter is probably accurate enough for my purposes. As a Home DiY calibrator / Hobbyist, re-certifying a meter is prohibitively expensive. The point of buying a used one is to get a high quality meter for not too much money. You just take the risk of not knowing how it's been treated.

When I compare readings from the 2 meters, they're actually very close. The x and y numbers are almost identical, which makes me confident that they're probably pretty accurate. The only real difference is that the ColorMunki "Y" readings tend to be about 2-4% lower than the i1Pro. I think I'll stick with the i1Pro because it just feels like a higher quality device.

Interestingly, readings from my i1 Display Pro are also pretty close to the i1Pro. In fact, on my Sony LCD their readings are almost identical. The correction matrix I generated for the LCD was very close to having no correction at all. On my LG OLED, the difference was more significant.
I am glad to see the issue has been resolved. By what you say about the Y,xy's , I would say the probe is fine.

The i1Pro is superior to the ColorMunki Photo.

That being said, the reason for this post is to ask if you have the X-Rite diagnostic software for the i1pro? ConnecTEDDD had posted the sight in the past where you can download it. A simple search request should be able to locate it. The question that comes to my mind is, "How critical is the need for the computer's display on which the testing is being conducted need to be calibrated? What color temperature does the monitor need to be set to? (Some monitors, especially older ones are set to approximately 5400 K , While newer ones, especially Apple monitors, are set to D65). I feel that testing is needed for every spectro, to see how accurate they are for the various purposes and conditions for which they are being utilized. The results for the parameters which it was evaluated for may not yield the same accuracy levels when used for any analytical testing that does not comply to the evaluation parameters. Have you ever reviewed the specs for the accuracy levels for the various spectros? One thing you will find is all accuracy levels for testing only utilize Illuminate "A" (approx. 2856K), and not for D65. The only spectro that does mention any testing other than Illuminate "A" is for the i1pro. I have attached the specs for the i1Pro, Jeti, Photo Research and the Minolta CS-2000; review for yourself.

This piece of software is worth having. If you contact X-Rite you may be able to get the Y,xy values from them. Having this, you can compare the test results located in the log file that can be generated.

This was stuck in my mind and had the need to mentioned. Good luck.
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post #10 of 23 Old 05-06-2017, 03:41 PM
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Originally Posted by Bloodwound View Post
I'd take the i1pro everytime. I am convinced these drift very little.

I have a rev A that is around 14-15 years old, and rev b that is 10-11 years. Both have been heavily used in printer profiling with x-rite IO robotic arm. They still more or less measure the same as my i1pro2.

In fact, from these "surplus" i1pros, I have made myself a "portable" calibration kit with i1pro + i1disp pro + hdmi output+cables. Fits very comfortably inside a little airtight plastic case and is perfect for somewhat less critical calibrations (family/friends/etc), and very travel friendly to boot. Using HDMI output for calibration is as always real hassle, but apart from that, using i1pro to profile the i1disp pro is a great combination.

True, with a used i1pro you cannot know for sure if it has sustained any damage. But really, if you compare the measurements with a i1disp pro, and the readings are in the same ballpark as the colorimeter, then chances are that it's fine.
The only problem we have seen on i1 Pros are when they have been damage by a drop or impact that has altered the mechanical alignment of the diffraction grating and CCD sensor strip.

One way you can check a spectro at home is with green and red laser pointers. Measure the spectrum of both lasers sperately (reflected off a white surface not directly into the spectro!) then export the SPD datasets to an excel file or CSV. Open the SPD data in excel and look at the peak value in the SPD data. A green laser has a wavelength of 532nm , so the peak value in the SPD data should be at 532nm. Obviously the i1 Pro doesnt have 1nm resolution, but you can still use this method as a sanity check.
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post #11 of 23 Old 05-10-2017, 09:29 AM
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Quote:
Originally Posted by WiFi-Spy View Post
The only problem we have seen on i1 Pros are when they have been damage by a drop or impact that has altered the mechanical alignment of the diffraction grating and CCD sensor strip.

One way you can check a spectro at home is with green and red laser pointers. Measure the spectrum of both lasers sperately (reflected off a white surface not directly into the spectro!) then export the SPD datasets to an excel file or CSV. Open the SPD data in excel and look at the peak value in the SPD data. A green laser has a wavelength of 532nm , so the peak value in the SPD data should be at 532nm. Obviously the i1 Pro doesnt have 1nm resolution, but you can still use this method as a sanity check.
Is this worth doing? I can score red-green-blue laser pointers off of eBay for less than $10. This would certainly check the spectral calibration, but would do nothing for the intensity. Any opinions?

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post #12 of 23 Old 05-10-2017, 09:57 AM
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Is this worth doing? Yes.

The laser pointers that can be acquired off of Ebay may not be as precise to a particular nanometer as stated but in reality could have as much as a deviation factor of +/- 5. For precision you can use a tunable laser if money is not part of the equation.

My suggestion is to conduct the aforementioned procedure stated by WiFi-Spy and record the values for future reference. In this way you will now have a point of reference for determining a major drift or if damage has occurred due to mishandling. Doing this procedure after the fact is in my opinion useless, since you have no point of reference in order to determine the extent of an issue.

The white surface that I would suggest using is a simple sheet of ink-jet photo paper which is very close the a calibration white tile.
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post #13 of 23 Old 08-17-2017, 08:35 AM
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I apologize for reviving an older posting.

I have received numerous private emails inquiring how to trace the accuracy of the i1Pro spectro. Since I presently have activities behind the scenes demanding my attention, I though I would convey the method that I have use for sometime now. This method is extremely similar to the method that WIFI-SPY mentions in this thread.

Here is the items that you will need;

1. - A piece of ink-jet Photo paper. ( I personally use a 4x6 sheet from Kodak which states that the finish is Gloss. In my opinion the finish appears to be more semi-gloss. I purchased the package for under $15.00 and has a quantity of a 100 sheets.)

2. - A set of laser pointers. ( I purchased mine on Ebay for the price of $10.00, which were manufactured in China. I spoke to an electronics engineer who stated that if you reserve the pointers usage exclusively for the testing of the probe the lasers should remain true for decades to come.)

3. - A computer and software. ( If you have the CalMan enthusiast of better, you can create a workflow with all the necessary parameters to do the job. For those that don't use CalMan then there is a piece of software called BabelColor CT&A. I have attached images of the results for the Red, Green and the Blue using BabelColor. Those desiring to use CalMan can easily mimic it in their workflow.)

4. - The Spectro. ( This illustration is addressing the i1Pro series but I can not find any reason as to why this would not work with other spectros. If anyone thinking that this might work with a colorimeter, please do not waste your time as the probe needs to read a Spectral Power Distribution and to the best of my knowledge colorimeters are not able to do this.)

Here is the method that I use. First, I lean the Photo paper upright as possible so that it does not require any further attention for this process.

I make sure that the computer and the software are ready to read the light emitting from the laser pointer.

Taking the laser pointer in one hand and the spectro into the other, I point the laser onto the Photo paper and press the read button on the spectro.

Once a reading has been obtained, I record the results and repeat the procedures for the other colors.

Through this method one is able to track over time if the probe is starting to drift and if so by how much. This method can also be used to evaluate the degree (if any), of damage as a result of being dropped or mishandled. Keep in mind that you will require a base line for such evaluations. If your probe is new, this method is great for establishing a starting point. If your probe has been purchased used, I can not stress enough for having the probe re-certified or tested against a known true secondary probe.

If you can see any improvement in the methodology pleas submit it for everyone to use.

Thank you.
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post #14 of 23 Old 09-12-2017, 03:10 PM
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For anyone interested in this technique - I just performed the test using a couple of years old i1pro2 with ArgyllCMS from the command line on OSX. ArgyllCMS is interesting as it has a high-resolution mode for i1pro/2 ( see https://www.argyllcms.com/doc/i1proHiRes.html for details). Cheap eBay laser set; 405nm blue/violet, 532nm green and 650nm red. All +/- 10nm.

To do this on ArgyllCMS you use spotread -e -H to read the lasers in Emissive hi-res mode (press s to save the spectral data to file after taking a reading) and then specplot to plot the resultant files.

Looks like we probably ended up with the same laser set (look the same in the photos). 650nm is equally offset, and the 405nm has the same characteristic "skirt" above it.
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post #15 of 23 Old 09-12-2017, 04:51 PM
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Cheap eBay laser set; 405nm blue/violet, 532nm green and 650nm red. All +/- 10nm.
I was actually wondering about that. Where did you find the specification of +/-10nm?

Quote:
To do this on ArgyllCMS you use spotread -e -H to read the lasers in Emissive hi-res mode (press s to save the spectral data to file after taking a reading) and then specplot to plot the resultant files.
You can also do this in HCFR, which may be (for some) easier than using command line and specplot. HCFR uses the ArgyllCMS driver, including the hi-res mode.

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post #16 of 23 Old 09-12-2017, 11:41 PM
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I was actually wondering about that. Where did you find the specification of +/-10nm?
I wondered the same then I read Randal_R's original post. In the case of these lasers it is printed on the label! See pic.
Of course, how much you choose to believe anything written on the label of a £1.66 laser from China (I paid £5 delivered for all 3) is up to you. But the testing would seem to bear it out.

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You can also do this in HCFR, which may be (for some) easier than using command line and specplot. HCFR uses the ArgyllCMS driver, including the hi-res mode.
Cool, I didn't know that. It was a bit of a pain operating the keyboard while trying to hold the laser and align meter. If I were to do again I'd try and use one of those "Helping hands" to position the laser, and give myself an aiming circle by looking at the shadow from the built-in light from turning on reflective mode for a couple of readings.

I wonder if the tail on the blue measure is something to do with the paper used.

I guess the tolerance of these lasers makes this test not so useful for evaluating a particular meter's capabilities - unless the response gives an obviously distributed spectrum instead of a peak, in which case you could be fairly sure the meter is broken. It is only really useful for tracking a meter over its lifetime. Eg; on looking at the results in my case I could look at the difference at 650nm and say:

1) is it the laser or is it the meter?
2) if it is the meter, is it a characteristic of all i1pro meters or just mine?
3) if just my meter, what does this divergence mean?

1) can only be addressed by buying lasers of a known higher quality or binning low quality meters and providing their reference data.
2) would need many people to test their meters against lasers of a known performance so a baseline could be understood.
3) needs all the above and someone who knows much more about this than I do!

A little market opportunity might exist for someone with a high-quality reference spectro. Selling lasers which have been tested and providing data for those lasers.
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post #17 of 23 Old 09-13-2017, 05:16 AM
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Originally Posted by bobof View Post
1) is it the laser or is it the meter?
Even though the meter costs >100 times the laser, I would actually tend to trust the laser, as the wavelength is "inherent" to the type of laser and not affected by manufacturing tolerance etc.

Quote:
2) if it is the meter, is it a characteristic of all i1pro meters or just mine?
I've just ordered a set of laser pointers from eBay and will post the results when I receive them.
BTW, what kind of paper did you use to reflect the light? Personally I think it would be easier to use matte paper than glossy paper.
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post #18 of 23 Old 09-13-2017, 05:50 AM
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I just used a piece of matte white card I had. I didn't really want to "invest" in this test, and have no need for inkjet paper...!

I think the blue response might be due optical brightener in the card I had.

I'm not really convinced how useful this test is for much other than testing if the meter has been heavily damaged (which I guess would probably show up from the diagnostic when used with matching tile anyway). @WiFi-Spy suggested this as a method to look for damage, nothing more.

You only get to see a peak at a given wavelength. You can't make any useful judgements of relative sensitivity to different wavelengths as you have no useful knowledge of your lasers and they're only emitting a single wavelength at a time (unlike a spectral lamp, which would emit several wavelengths with an understood relative intensity).

When I did this test I did it in the dark, and would get quite variable measurement intensities depending on how well I aligned the meter. The spectrum shape always remained the same and in the same position, assuming I was hitting the laser light at all. The laser spot is very small I think - too small compared to the field of view of the meter when it is raised off the paper.

I am certainly no expert, but...

In looking for changing meter characteristics over time - to try and avoid factory calibration - I figure you need to understand that both the wavelength detection and relative wavelength sensitivity is accurate (plus the calibration of the absolute intensity if you're not just using the colour measurement capabilities). From what I understand this laser method as described could only ever get you to part of the way to understanding that the wavelength detection hasn't shifted significantly for a given set of lasers.
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post #19 of 23 Old 09-13-2017, 06:04 AM
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I just used a piece of matte white card I had. I didn't really want to "invest" in this test, and have no need for inkjet paper...!
I think the blue response might be due optical brightener in the card I had.
My understanding is that optical brightening agents (OBAs) react primarily to UV. I will check that when I receive my laser points. I have boxes and boxes of inkjet paper, with and without OBA

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post #20 of 23 Old 09-13-2017, 06:32 AM
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edit: Looks completely expected:

https://en.wikipedia.org/wiki/Blue_laser
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Some of the most commercially common blue lasers are the diode lasers used in Blu-ray applications which emit 405 nm "violet" light, which is a short enough wavelength to cause fluorescence in some chemicals, in the same way as radiation further into the ultraviolet ("black light") does.
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The violet 405 nm laser (whether constructed from GaN or frequency-doubled GaAs laser diodes) is not in fact blue, but appears to the eye as violet, a color for which a human eye has a very limited sensitivity. When pointed at many white objects (such as white paper or white clothes which have been washed in certain washing powders) the visual appearance of the laser dot changes from violet to blue, due actually to fluorescence from brightening dyes.

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post #21 of 23 Old 09-13-2017, 07:54 AM
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Tyler only described it as a "sanity check" to see whether or not anything had shifted in a used meter that might have been dropped. I used the test to check my I1 Pro (which has been dropped 12" to 18" a couple of times) and my newer I1 Pro 2 (which hasn't). Both returned similar results.
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post #22 of 23 Old 09-13-2017, 09:12 AM
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edit: Looks completely expected:
Instead of white paper which may contain OBAs, I presume you can put the ambient light diffuser on the i1Pro and aim the light at it instead.

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post #23 of 23 Old 09-15-2017, 07:00 AM
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For what it is worth, using a diffuser instead of the the paper as a reflector gets rid of the shelf in the blue trace - it is caused by the fluorescence of the paper I was using in my case. I couldn't get consistent readings with the ambient head (as the diffuser dot to hit is very small and I didn't have time to rig something up which could fix the positions) - but using another diffuser and firing the laser onto that worked fine.

Having read up a bit on CCD sensors being damaged by lasers I'm not sure I'd want to make a habit of aiming lasers (even if they are being reflected off paper / via a diffuser) in the vicinity of the i1pro.

And I'm really not convinced of the value of this as a test other than checking for a badly damaged meter. Plus I would have thought the self-test using the calibration tile would show up a badly damaged meter anyhow.

Does anyone have examples of bad meters which would look OK on the ceramic tile test, perform seemingly "alright" in use but would show failing characteristics on a test with a laser? If so, can anyone share a spectral plot of such a failing meter? Does it even make sense to consider this as a way of watching for "drift" in a meter, given that as far as I can see it can't show anything of the relative sensitivities to different wavelengths? Nor give any clue as to the absolute sensitivity?

Tagging @gwgill and @WiFi-Spy as they seem to have the most tech experience of these meters.
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