A new colorimeter
Times change. 10 years ago a computer with the power of a single pentium III/1000 would have been a 20 processor (or more) sequent with a price exceeding $1.5M. Today you can get this for <$1200.
10 years ago a spectrometer (colorimeter) was large and heavy, used
diffraction gratings or prism's and photomultiplier tubes and cost
tens of thousands of $. A brand new perkin-elmer instrument these
days is built the same as it was 10 and probably 20 years ago, and
starts at $80k. Not really practical for home calibration.
(unless you also own a fork-lift)
Over the past 5 years a number of hand held instruments have appeared
to do the spectrometer function. They fall into two different categorys.
The first category is instruments like the photoresearch pr640, the
mcmahan lightspex, pritchard pr
-100, minolta cs200a and others.
The first two use multipoint silicon detectors with resolution ranging
from 64 to 128 points. The last two use photomultipliers and have
resolution from 256 to 1024 points. All of these devices share a
common characteristic, their price. The cheapest of the bunch is
$4500. A little much for people to spend for home use.
The second category consists of devices like the minolta mc7 and ca-100, the optimate I and II, the xrite-dtp92, the macbeth spectrolino, and the sequel chroma4. All are tri-stimulus devices which means
that they have one sensor for red, one for green and one for blue.
Some of these sensors have integrated optical filters, some use plastic glue on's. These devices are great for their real intended use,calibration of direct view crt's. As such their filters try to
match the phosphor characteristics. Great for crt's, lousy for
lcd monitors, and even worse for front (or rear) projection lcd
(including dila) and worst yet single chip dlp projectors because
the spinning wheel drives the detector nuts unless it is properly
sync'd. These devices have market pricing ranging from $249 to
$1295 (not usually including software). Attempts to make these
devices do what they were not designed to do has resulted in numerous
Enter a new class of colorimeters. The device is priced for home
use. It has 7 color sensors instead of 3. (not counting the additional
sensor used to determine refresh rate if any). It contains sharp
optical filters that lose less than 1db in the passband as compared
to 4 to 6 db for the tri-stimulus sensors. (precision diffraction grating) Since there are more sensors across the 400nm to 700nm optical band the necessity to adjust the readings after they are taken from the sensor for different display devices disappears.
Sensitivity and color accuracy improve. A factor of 5 or so over
older tri-stimulus designs. Color temperature accuracy is better
than 100 degrees at .1 footlamberts. Price of the detector with
some really excellent software is <=???.
(note, 3 digits, middle 3 digits)
(mark asked me to delete the price)
This is the sensor that dilard will be recommending for home use.
Although we will also support the sequel chroma 4 and the minolta
units. We will also be supporting a 500 point unit that i am
building personally. It has gone up in price a bit because
the hamamatsu r636 GaAs detector i am using is more than i wanted
to spend and hamamatsu seems unwilling to rebuild this device
into the smaller package with one or 2 less dynodes. But it is
absolutely amazingly flat across the entire visible spectrum and
beyond in both directions...