You cannot fool all the people all the time.
Why are you bringing up this curve. I covered this topic with you here:
You are now getting malicious with your attacks. Taking my post and putting your spin it with obvious ill intent.
I went easy on you there were other points about your misguided advice that I skipped So I will take yet even more time. Maybe this time something will stick in your troubled mind. Are you blind to how wrong you have been on nearly everything you have said in the past couple of weeks???
The sensors used in Lux meters are similar (if not the same) as those used in cheap PAR meters. They are also sensitive over the whole range.
More bullshit. The Lux meters do NOT use the full Photopic bandwidth.
The ALS curve you unscrupulously shows the bandwidth before filtering. After it is filtered, the range is about 500-600nm.
Wrong. The lumen CIE curve extends all the way from 380nm to 780nm. The amplitude is less at the extreme ends, but it's still measured and therefore it works perfectly fine to measure light of any (visible) color.
First off a lux sensor uses one single photodiode. A photodiode is very similar to a solar panel's photo-voltic cell. When the light excites the photodiode anywhere photodiodes memory effect "stores" the energy created when a photon strikes the photodiode. All that is measured is the number photons. There is no way for it to distinguish between wavelengths and therefore cannot reveal any spectral information.
A PAR meter's sensor use multiple photodiodes with various wavelengths. So NO, lux and PAR meter's do NOT use the same sensor.
The CIE Photopic Luminous Efficacy goes from 390 to 770
At 390nm the sensitivity is 12
At 550nm the sensitivity is 99,495
At 770nm the sensitivity is 3
An ALS is very sensitive to UV and IR so the blues and reds are filtered out. Bu that may not be the reason.
Wrong. The lumen CIE curve extends all the way from 380nm to 780nm. The amplitude is less at the extreme ends, but it's still measured and therefore it works perfectly fine to measure light of any (visible) color.
The center of the curve is 555nm which CIE set its value at 100,000.
One sec in a sensors datasheet is FWHM which is the point in the curve that sensors read and report, Full Width Half Max is the 50% point in the curve. Guess whch wavelengths are at 50% of the CIE Photopic Luminous Efficacy curve. The two points at 50% are 510nm at 50,300 and 610nm at 50,300. So No! A lux meter would never look beyond 510nm and 610nm
The Texas Instruments OTP3001 and OTP3002.both use the same photodiodes as you said. But purposely leaving out the rest of the story is the same a lying.
.
The 3101 is targeted to lux markets e.g Lighting Control Systems.
The 3002 Medical and Scientific Instrumentation
TI says Use the OPT3002 in optical spectral systems that
require detection of a variety of wavelengths, such as
optically-based diagnostic systems.
The OPT3002 Response Curve,
looks a lot like your curve that you deceitfully attempted to pass off as a lux sensor's
.
Notice no filter before the sensor
The OPT3001-Q1 device is a single-chip lux meter,
measuring the intensity of light as visible by the
human eye. The precision spectral response and
strong IR rejection of the device enables the
OPT3001-Q1 device to accurately meter the intensity
of light as seen by the human eye, regardless of light
source.
This curve looks like EVERY response curve for Lux only markets.
Notice the filter before the sensor
More wanton and willing deceit
For a lux meter they add a color filter to tone down the blue and red ends
There you go again trying to Baffle with your Bullshit. "Tone Down"
The ALS curve you show is before filtering. When filtered the range is about 500-600nm.
The CIE Photopic Luminous Efficacy goes from 390 to 770
At 390nm the sensitivity is 12
At 550nm the sensitivity is 99,495
At 770nm the sensitivity is 3
An ALS is very sensitive to IR so the reds are filtered out.
I have to assume you do not understand the need for a cosine sensor
A high end sensor has cosine correction. They cannot use the cheap lux sensors.
The cosine sensor has an aperture much smaller than the sensor. The sensor has many photodiodes. The lux sensor has one photodiode. When the light comes through the aperture at an angle the beam of light will not excite the center photodiode. The angle can be obtained from the cosine of the height (aperture to center photodiode) and the angle of the beam. The angle is calculated by using the acrtangent of the height and distance from the sensor's center to the photodiode that was excited by the light beam.
Additionally a really high end lux meter will use an expensive CCD sensor rather than a photodiode.
My spectrometer has a cosine sensor. That is why ISL works. That is why Greying Geeks lux meter did not follow ISL.
I ntices yu did not understand at least tw of the lines of cde where yu accusded me of fudging the numbers. These two line were taking the cosine into the app.
$angle = rad2deg(atan( $offset/$height));
$distance= $height / cos(deg2rad($angle));
More is posted elsewhere explaining these two line in great detail.
Because a lux meter does not have a cosine sensor it cannot follow ISL or detect uniformity very well. It is NOT a good tool to use for adjusting the height of a fixture.
To see why you think ISL does not work, look at my post where you gave Greying Geek your typically bad advice. I tried to explain the same thing to you but you do not listen to what I have to say.
As you can see, his intensity drop from 4 inches to 8 inches was only about 6% - 51k lux to 48.2k lux. ISL predicts a 75% drop. Even at 24" down he still has not hit 50% drop.
I posted a rely to Greying Geeks post regard ISL
This is the post:
)
