Florescent glow pigment at a high luminosity with long decay time 
http://proglow.com/pigment.htm
Attenuation Diagram
http://proglow.com/diagram.htm

If we had some plastic products with this pigment manufactured as part of it, we 
will find some interesting uses after the PS.  It is a bit expensive to buy in 
this raw form.  Florescent fishing lures and light switches, flash light cases, 
and florescent tape could have many uses.  Painting the inside of a survival 
quarters, dome would be one use.  Would need to use a water sealer, moisture 
will degrade the florescent effect.  I think plastic products that are 
florescent to be more practical.  You can buy at most toy stores animals, stars 
and planets to put on your wall at night that glow.  From this plastic one can 
make other things as they are needed.  Markers for places to find in the dark 
would be the primary use.



----------------------------- 
Sent: 18 April 99
Light Measurement Handbook,
http://www.intl-light.com/handbook/index.html

Light Sources
http://www.intl-light.com/handbook/ch05.html
Basic Principles
http://www.intl-light.com/handbook/ch06.html
Measurement Geometries
http://www.intl-light.com/handbook/ch07.html
----------------------- 
Special Meters
http://www.elexp.com/tst-spec.htm
Model: LX - 101 --- $65.95
http://www.elexp.com/tst_lx01.htm
Model: LX-02  ----- $39.00
http://www.elexp.com/tst_lx02.htm
Light meters
http://204.127.238.82/visiblelight.htm

----------------------------- 

LED Flashlight Bulbs source
Sent: 18 April 99

100,000 - Hour LED Flashlights, Electronic Strobes and Replacement Bulbs (flash 
lights)
http://www.americaworks.net/lighting/index.html

----------------------------

Safety Lights!
http://www.shopthegroove.com/stgbrightideas.html

Lights
http://bikeusa.com/accessories/lights2.htm

LED lighting is now available for indirect and direct lighting applications. The 
can flash, strobe, change colors, and a host of other functions while consuming 
very little power and they generate almost no heat compared to incandescent 
lighting.
http://wagnersign.com/leds.htm
 ------------------- 
Outdoor 
WATTS Lumens  Hours   Cost/year
2x120 3460    2000    105.12    Incondesent standard
4x120 6960    2000    210.24    incondesent standard
70    6300    24000   35.92     Sodum high pressure
90    1280    2000              Philips Halogen flood
100   4500    24000   51.68     Mercury
125   6000    24000   67.45     Mercury
175   7900    24000   89.79-73.58 Merurcy
---
13 60w equil 10000              Compact Fluorescent Quad Lite
40    400     2466              Deluxe Extralife (130V)
40    460     1500              Bonus Brand Standard
40    490     1000              GE soft white
40    495     1250              Philips soft white longerlife
53    444    15000              Feit Electric Rough Service (130v rating, 120V 
operation)
60    600     5000              Feit Electric Rough Service (130V)
60    840     1250              Philips soft white longerlife
60    850     1000              Action Tungsram
75    1210    750               Bonus Brand Standard
100   1630    750               Feit Electric (120V)
100   1750    750               Bonus Brand Standard
150   2780    750               GE soft white
200   3910    750               Ge Soft white
 ------------------- 

subject: Useful Light intensity
Sent: 6 feb 99

Roger wrote:
> 
> *** Troubled Times forum mailing list ***
> Wow Mike, I didn't know there was going to be a quiz (lol).

No quiz intended.  The data was given for those who do not have access to a 
light meter, to indicate some of the factors to take into account in calculating 
light intensity.  I realize with your physics background you are quite aware of 
these factors. 

>  I was
> trying to understand how a 6 watt bulb could provide enough light for
> plants within a square meter.  I don't think this is correct. Your
> postulate below certainly accounts for this.  But do we need to do these
> calculations, or has someone already done so, and if so, what is the
> bare minimum wattage of light needed for the average plant within a
> square meter?


I didn't originally understand this as your purpose. But, now that I do - 
Initially, I agree it doesn't sound like much light or that it is correct.  
However, in looking more deeply into it I have found the following. 

One candle = 12.5 Lumen = amount of energy (as light) a light source emits. 
Light bulbs some times are rated in this way.  You can look on some bulb 
packages and get watts and number of Lumen or amount of light it puts out. 

Lux = is the rate of energy falling on a surface as a result of light hitting 
it.  One can think of it as the amount of light hitting a given square area of a 
surface. 

I found the following Equivalents:

One foot-candle (foot-candle)= One Lumen per SQ. Ft. = 10.76 Lumens per Sq. 
Meter (or LUX) = .00176 Lumen per sq. Cm. (Phot)

One Lumen (at 5,550 Angstroms) = .00147 Watts
one Sq. Ft. = .0929 Sq. Meters

Thus at 5,550 Angstroms of light: 
on foot-candle = .00147 watts per Sq. Ft. = .0158 Watts per Sq. Meter
Or, one Lux = .000136 Watts per sq. ft = .00147 watts per sq. meter
or, one watt per Sq. meter = 680 Lux
or, one watt per sq. ft.   = 7320 Lux

Brightness Values: (electronics reference (Magnavox))
light source                      Lux  Watts/ft2 Watts/m2
Office fluorescent Lighting   300-500  .04-.07   .44-.73 
Halogen lamp                      750  .102      1.10
Sunlight, 1 hour before sunset   1000  .136      1.47
Daylight, Cloudy sky             5000  .680      7.35
Daylight, Clear sky            10,000  1.36      14.7
Bright Sunlight              > 20,000  2.72      29.4

Note that the above watts/sq. ft and watts/sq. meter is the amount of energy in 
the light and not the amount of watts that it took to make the light.  Many 
light bulbs are inefficient.  Typically only 10% of the energy goes to make 
light in vacuum tungsten filament light or possibly up to 20% with halogen 
bulbs.  Florescent are about 70-90% efficient. 

I pulled the following quotes from link:
http://www.litemanu.com/lightingqa.html

"Under natural conditions, maximum rates of Photosynthesis are attained in 
single leaves of many species at 25-35% of full sunlight intensity and in some 
shade species at even lower intensities."

If one now takes 25-35% of 14.7-29.4 watts/sq. meter one gets 3.7 to 10.3 
watts/sq. meter or an average of 7 Watts/sq. meter.  Note that this is very 
close to 6 watts/sq. meter.  Thus I believe Steve is correct. 

Now lets start from scratch and calculate an estimate amount of light hitting 
your plants.

From "Handbook of Engineering Fundamentals" by Eshbach second edition.  
Efficiency of light sources table 4 page 10-33.

Light source             efficiency (lumens/watt)
tungsten gas filled      20
tungsten vacuum lamp     10
Fluorescent: (includes ballast loss)
 standard cool white     46.5
 standard warm white     51.2
 de luxe cool white      29.0
 de luxe warm white      31.0
 daylight                41.3

Depending on the bulb used you could be putting out 29lumens/watt*40watts= 1160 
lumens or 51.2*40= 2048 lumens of light. 

We now will calculate the Lux using the formulas following table 1 in the 
following link: 

Environmental Effects of Roadway Lighting
http://www.darksky.org/ida/info125.html

Street lamps are designed to direct a high percentage of their light toward the 
street (45%).  Let assume your lamps are less efficient say 30-40% of the light 
generated falls with in the .39 area of useable space.  Lets assume we can keep 
the bulbs clean and that aging is the only factor of say about (.8).

Illuminance of 4 (40 watt florescent tubes) =
(L*CU*LLF)/(S*W)=
[4*(1160 to 2048 lumens)*(.3 to .4)*.8]/(.39 sq. meters)
= 2855 Lux to 6721 Lux.  (Or an average of 4788 Lux)

What should we expect to need? (7 watt)*(680 Lux/watt per Sq. meter) = 4760 Lux 
would be the minimum from above. 
Steve says: Tomatoes grow best at 4000 Lux, 18 hours a day.  If the hrs decrease 
to 12 hrs that 22% decrease in time and now if we add 22% to 4000 Lux we get 
4880 Lux.  Very close to the same result. 

Bottom line: Depending on the bulb you are using and the actual efficiency of 
light delivered to the useable area of .39 sq. meters you both are talking about 
the same order of magnitude of light. 

More information on definition of terms can be found at:
FAQ: Lighting and Illumination
http://www.ie.psu.edu/courses/ie408W/lectures/lightingfaq.html

Feel better now? I know I do it took quite a while to get this subject straight 
in my mind.  This is one subject we may need at least one person proficient at 
understanding the calculations in each community after the PS.  So as to not 
waste energy. 



-------------- 

Subject: Light efficiency of metal halide bulbs

While we are at it we might as well determine how the following recommendation 
was arrived at for metal halide 1000 watt lights. 

http://www.litemanu.com/lightingqa.html
"Q: How much Light do I need?" (was for growing plants)

"A: 20-40 watts per sq. ft. is a general guideline. The more efficient the Light 
source, the less watts per sq. ft. needed. For example using 1-1000 watt metal 
halide light, in a 50 sq. ft. area would give you 20 watts per sq. ft. and a 
total of 120,000 lumens."

Solving the equation given in the following link for "CU" or the coefficient of 
utilization of light: 
See Environmental Effects of Roadway Lighting
http://www.darksky.org/ida/info125.html

We get:
Cu = (E*S*W)/(L*LLF) =
(4760Lux*50sq.ft.*.0929sq.meter/sq.ft)/(120,000lumens*.8)=
.23 or 23% efficient.

In other words we need at least 23% efficient reflector to direct the light to 
this 50 sq. ft. area to get our minimum 4760 Lux amount of light to grow plants 
for 12 hrs/day. 

Now what about the electrical efficiency of the 1000 watts converted to 120,000 
lumens. 

Recall that: One Lumen (at 5,550 Angstroms) = .00147 Watts.

Actual light energy in wattage = 120,000lumen*.00147watts/lumen= 176 watt of 
light from a 1000 watts consumed. The difference is emitted as heat.

Thus the electrical Light efficiency = 176watt/1000watt =.176
or 17.6% efficiency. 

Summary: This setup converts 17.6% of it's energy to light of which 23% will 
need to fall with in the 50 Sq. ft. to make plants grow. 

--------------------- 

Subject: Light or Lux meters

Looks like to minimize calculations and guessing and to maximize reflected light 
to our plants, one will need a light intensity (Lux or foot-candle) meter of one 
type or another.  We will ultimately need a table of minimum to optimum Lux for 
a given hours per day for each class of plants we intend to grow.  To balance 
the red and blue intensity, some of us will need to measure to an extent color, 
chromaticity, or Kelvin temperature. 

The following is a review on one type of Lux Meter product. 

http://www.animalnetwork.com/fish/aqfm/1998/june/product/
An Inexpensive Light Meter and Its Application to Reefkeeping

Where to buy a Lux meter?  The following is some of the alternatives.

http://www.omnicontrols.com/lists/n_extech84.html
Extech  Model 401025           $119

http://www.bhphotovideo.com/photo/meters/sekonic/lux.html
SEKONIC L-246LX                $149

http://www.central-camera.com/SEKONIC.HTM
Sekonic L-158                  $59

http://www.cameratradersltd.com/usedmeters.htm
Used Light Meters              $69 and up

http://northcoastmarines.com/lightmtr.htm
ACQUAMARINE LIGHT METER        $45

I know that a light intensity or Lux meter can be built out of a simple solar 
cell and a digital current meter for less than $20. The question is if one did 
this without a reference meter as a standard, how does one calibrate it?  All I 
can think of right now is a candle one foot away for the low end and the sun for 
the high end.  Aside from there being no sun after PS, both are not a good 
stable, non-variable source.  Building a color or Kelvin meter is another story.  
Possibly using the same Lux meter with some color filters would serve our 
purpose.   Any ideas?

Roger, did you find a more cost effective product (light meter)?


--------------- 

> > Did you take in to account the wasted light that escapes hitting the
> > plants?
> >
> > One way to estimate how much light your plants are actually getting:  4
> > ft florescent tubes radiate light cylindrically mostly. Thus if one
> > determines a cylinder of diameter (average distance to center of the
> > plant) and about 5-6 ft long.  Assuming your plant is not too far away.
> > Determine this surface area of this cylinder and the percentage of the
> > area used by the plants at this distance.  This becomes the same % of
> > the wattage of the original bulb.  Subtract about 10-20% from the
> > wattage of the bulb due to inefficiency of conversion from electricity
> > to light.   There will be some reflection from the back reflector on the
> > light.  Assume this to add approximately 50% to 100% more light on the
> > plant area.  Take into to account the multiple florescent tubes you have
> > in close proximity.  The result is an estimate of the number of watts
> > actually hitting the plant which can then be divided by the area of
> > light the plant actually uses to get the watts/area.
> >
> > hope this helps.
> >
> > 






 ------------------- 

Look for red diode array and a gas discharge bulb centered on the blue spectrum.
 ------------------- 
subject: LEDs
http://www.elexp.com/opt-led.htm

 ------------------- 

subject: LED Flashlights are coming
Sent: 27 sep 98

Keep you eyes open for LED Flashlights.  They should become more and more 
commonly available as we approach the PS.  100,000 hr bulb life is more than 11 
years running 24/day 7 days/week.  Battery life is greatly extended due to bulb 
efficiency.  Some examples of what is currently available. 

THREE "AA" ALKALINE WHITE LED FLASHLIGHT - The light lasts at a super bright 
level for a continuous 48 hours
http://ccrane.com/ledflash.htm

Photon Micro-Light key chain flashlight - The BRIGHTEST for its size personal 
flashlight!! Shines bright for 124 hours with one battery.
http://www.photonlight.com/main.htm

How to convert and existing flash light to work with a Red super bright Radio 
Shack LED - Battery lasts 20 times or more longer - Cost $3.00
http://athos.rutgers.edu/~watrous/ledlite.html

comtrad industries has a eternalight pocket flashlight that lasts 700 hrs using 
3 AA batteries.  Has various modes of operation. Cost is a bit high $59.95. call 
800-704-1211.

 ------------------- 
Light energy is rather different from heat energy, though it is
 given out by things that are very hot. Boiling water is 100°C, a
 red-hot electric radiator is about 1000°C, a light bulb filament is
 about 3500°C and the surface of the sun is about 6000°C. (Some
 things however, such as the phosphors in fluorescent lights or in
 the screens of television sets, give out light by electrical processes
 at room temperature.) 
http://www.science.org.au/nova/037/037box03.htm

 ------------------- 

Subject: Electric lighting
sent: 29 Nov 97

Found this while looking for something else:


From: HOW THINGS WORK
By: Louis A. Bloomfield, Professor of Physics, The University of Virginia
http://www.phys.virginia.edu/Education/Teaching/HowThingsWork/home_nov_1996.html

"Electric discharge lamps are between 2 and 5 times as energy efficient as 
normal incandescent light bulbs. The hot filament of an incandescent lamp 
delivers only about 10% of its electric power as visible light. In contrast, a 
florescent lamp delivers about 25% of its electric power as visible light and 
some gas discharge lamps (particularly low-pressure sodium vapor) deliver as 
much as 50% of their electric powers as visible light."

How much life is consumed each time you turn on a fluorescent lamp? -- BL, San 
Jose, CA

    "The starting process erodes the electrodes of a fluorescent tube through a 
phenomenon called sputtering. A typical fluorescent tube will last about 50,000 
hours if left on continuously but only 20,000 hours if it's turn on for just 3 
hours at a time. From that tidbit, I think its fair to say that a fluorescent 
tube can only start about 10,000 times. If the tube costs $5, you are spending 
about 0.005 cents per start. If the electricity to operate that tube costs about 
0.2 cents per hour, then turning the tube off for about 1.5 minutes saves the 
same amount of money in electricity as it costs in tube life when you turn the 
tube back on. In short, if you turn the lamp off for less than about 1 minute, 
you're wasting money. But if you turn it off for more than 10 minutes, you're 
saving money. In between, it's not so clear. There is a myth that turning on a 
fluorescent lamp consumes a huge amount of electricity so that you shouldn't 
turn the lamp off and on. There is simply no basis to that myth." 

My comments on this - based on the data above if a fluorescent lamp is left on 
for over 7 hr. each use, then should get maximum life.


What are the different types of light bulbs and how do they work? - BS

    "An incandescent light bulb works by heating a solid filament so hot that 
the filament's thermal radiation spectrum includes large amounts of visible 
light. A fluorescent tube uses an electric discharge in mercury vapor to produce 
ultraviolet light, which is then transformed into visible light by fluorescent 
phosphors on the inner surface of the tube. A gas discharge lamp uses an 
electric discharge in a gas inside that lamp (often high pressure mercury, or 
sodium vapor, or even neon) to produce visible light directly."

What is the composition of the phosphors used in fluorescent light bulbs? - M

   "The exact composition depends on the color type of the bulb, with the most 
common color types being cool white, warm white, deluxe cool white, and deluxe 
warm white. In each case, the phosphors are a mixture of crystals that may 
include: calcium halophosphate, calcium silicate, strontium magnesium phosphate, 
calcium strontium phosphate, and magnesium fluorogermanate. These crystals 
contain impurities that allow them to fluoresce visible light. These impurities 
include: antimony, manganese, tin, and lead. 

Do regular fluorescent lights emit ultraviolet light? If so, how does the 
ultraviolet level compare to what we would receive if we were outside? -- GF, 
Barstow, CA

    "While the electric discharge in the tube's mercury vapor emits large 
amounts of short wavelength ultraviolet light, virtually all of this ultraviolet 
light is absorbed by the tube's internal phosphor coating and glass envelope. As 
a result, a fluorescent lamp emits relatively little ultraviolet light. I think 
that the ultraviolet light level under fluorescent lighting is far less than 
that of outdoor sunlight." 
