This web page is part of my interest in optics and light. When optics is combined with electronics you get electro optics.
Ultraviolet light (Wiki) has a wavelength shorter than visible violet light (Wiki, 400 nm) and longer than X-Rays (Wiki, 100 nm). Atmospheric absorption stops the shorter wavelengths from getting to the earth's surface, but the longer (near violet) wavelengths do get to earth can cause sun burn.
Table from Wiki Subtyypes
UVA 315 - 400
Long wave black light
Causes sun tan.
Blue when off
UVB 280 - 315
mostly absorbed by ozone layer
White when off
100 - 280
Short wave, germicidal,
completely absorbed by the ozone layer and atmosphere
For general information about various sources of light see my lights web page.
Wiki) - and especially Halogen lamps (Wiki) because the quartz bulb passes UV, but even a normal filament lamp but with a quartz bulb will make a usable UV source.
185 - 254 nm UV-C , 5 Watts.
1. Press and hold the button until the LED turns Blue. This same LED will be Red when charging.
2. Place lamp in confined space and leave before it turns on. Note time. After a time delay the UV lamp will turn one.
3. After more than 15 minutes the lamp should have run out of power. Check if light is still on by looking away and if still on close door and wait a few minutes.
4. When light has turned off you can recharge it.
Fig 2 USB-C for charging.
Fig 3 You can smell the ozone.
Sirchie web page for the 790UV - Alternate Light Source (ALS) - "A wide beam of 365nm UV light is useful to scan large areas for evidence at the crime scene. Evidence such as fibers, bone fragments, physiological fluids, and others can fluoresce in the presence of UV light, uncovering what was hidden without it."
Wiki) - typically high pressure tubes.
2 Foot Glowing Blacklight
From Halloween Club. Uses 20T12-BLB lamp. UV-1 368 nm (see: GE)
On/Off switch is on left end. Polarized 2-prong plug on cord on right.
Glowing beads and cap on plastic bottle.
Grimes AN-3038-1 aka C-5 (see Electro Optic Gadgets)
ercury-vapor gas-discharge lamp where in normal lamps the inside of the glass tube is coated with phosphors (Wiki) that are excited by the UV light and radiate visible light. But a UV fluorescent lamp has no phosphors and sometimes is made from a glass that transmits UV light better than common glass.
Wiki) - Near UV (375 - 395 nm) are commonly available for low cost, but the shorter wavelengths (down to 240 nm) cost a lot more and are used for things like Alternate Light Source (Wiki: ALS) applications like viewing crime scenes. Experimental LEDs at 210 nm are in labs.
2020 May 8: received a couple of 280 nm UVC LEDs. They may be some variant of the Luminus p/n: XST-3535-UV-A60-CE275-01 (Mouser).
Metal package size is 3.5 x 3.5 mm.
Vf 5.0 to 7.5 V @ 350 mA. 280 nm peak. The Fluke 87V DMM shows nothing in either polarity in Diode mode.
There is a clear quartz? window set into the gold metal package.
Uses a GE Ozone gas discharge lamp No. G4S11. This lamp has the look and feel (Don's Bulbs) of the UV GTL3 shown below.
On the Pic List there was a post saying the G4S11 can be wired in series with a standard 40 Watt filament lamp which will act as ballast.
E17 (Wiki) base.
438310 Lamp Base, Thomas A. Edison, 1890-10-14, 439/176; 200/51.17; 313/315 -
Fig 1 The transformer provides the filament voltage and
acts as ballast (Wiki). Note drop of Mercury in bulb.
Clips are to hold one of the 3 supplied filters.
Fig 2 GE G4S11 "Protect Eyes"
Fig 3 Note low or no reading on J-221.
This is not Wood's glass (Wiki) since it appears clear.
Wiki) power supply.
Halogen Desk Lamp
Off: 0.001 mW/cm2
On: 0.019 mW/cm2
On-w/o Glass: about the same?
glass marked: UV Filter-001
sometimes reads 0.010 and other times 00.1 (auto ranging)
00.26 mW/cm2 (max w/glass UV filter)
00.48 mW/cm2 w/o glass UV filter
The vibrator has 4 pins, two are 0.154" dia with one of them strapped to the case, and two are 0.123" diameter.
YouTube: 1951 PONTIAC CAR RADIO RESTORATION Pt 3 Vibrator restored -
If the lamp with built-in lens is a 222 then 2.25 Volts @ 0.25 Amp.
The voltage drop across 15 Ohms at 0.25 Amps is 3.75 Volts. 2.25 V + 3.75V = 6.0 Volts so that's the battery needed at the input.
After applying 6 VDC (from an HP 6038A with a very noisy fan) the light works: YouTube: https://youtu.be/SExRr9Ihukk
Fig 3 Empty top compartment. why?
Center compartment is vibrator
Lower coal tar potted compartment is HV transformer.
Fig 5 SPDT switch (center off), 15 Ohm resistor in series with 222 lamp.
Switch selects either 222 white light or UV light.
Fig 6 Schematic
Wiki) have a continuous spectrum from 180 nm to 370 nm and in addition peaks at 486 and 656 nm as well as a band from 560 to 640 nm.
5057742 Discharge tube, Hamamatsu - more vibration resistant and longer gap between pins with HV
5552669 Deuterium gas discharge tube, Hamamatsu
5646487 Lighting device for gas discharge tube with insulated discharge shielding member - focusing elecgtrode, Hamamatsu
7271542 Gas discharge tube, Hamamatsu
J-221 long wave (300 to 400 nm) meter: 0 to 12 & 10 to 60 uW/cm^2 - typically used for blacklights (Wiki).
J-225 short wave(230 to 270 nm) meter: 0 to 24 & 10 to 120 uW/cm^2 - typically used for germicidal (254 nm) lamps.
Yellow Filter No. 50107: removes all UV light leaving only IR light. To get a UV only reading Subtract 1.06 * Yellow filter reading from the no filter reading. see TouTube video below.
UV [only] = No Filter reading [UV + IR] - 1.06 * (Yellow Filter reading) [IR reading corrected for filter loss]
The yellow background on the meter face contains a phosphor that glows after UV exposure. (That's why I shine each UV flashlight at the meter face in the video.)
Has two meter ranges: 0 to 12 uW/cm^2x100 and 10 to 60 uW/cm^2x100
26 April 2019 outside around 3pmmeter reads 14 on B range w/o yellow filter, and meter reads 7.6 with filter. To get final reading multiply meter by 10.
So the direct Sun is1400 uW/cm^2 and through the yellow filter the Sun is 760 uW/cm^2.
Fig 4 Remote sensor capability might be handy to
avoid operator exposure to strong UV.
Blak-Ray Ultraviolet Meter Model J-221
International Light Technologies Model IL1400A Radiometer/Photometer with SSL001 Slim UV Probe & CC500 cCarry CaseThere are different models, this one is the original button keypad version (IL1400A manual).
SSL001 UVA Super-Slim Probe (PCB photoresist exposure is common application)
Dynamic Range: 1.11e-5 to 9.00e-1 W/cm² (limit exposure to prevent heat damage).
Spectral Range: 260 - 400 nm.
Dimensions: 29 x 38 x 2 mm
The SEL623 and SEL624 are thermopile sensors with very broad wavelength ranges.
IL1400A Fig 1 - 4 AA Batteries
IL1400A Fig 2 SSL001 Slim UVA Probe (375nm peak)
IL1400A Fig 3 Afternoon Sun Oct
It turns out the UVC light will turn green bananas brown. See:
YouTube: A hint that your uvc light is working,UVC. The green banana test.
Things to look at with a UV light.
This application goes back many decades, the oldest UV light I have is from my father's interest in rocks and minerals.
Geology.com has a web page about this.
In high shool I was in the Air Scouts and we met at Moffett Field. They had Link Trainers (Wiki) that were fixed to the floor and about 30 feet long.
There was a cockpit and a teachers console. The instrument lights were UV and the markings and needles were phosphorescent. That way a pilot preserved his night vision while still being able to easily read the instruments. There are some photos taken using UV light on my Aircraft Clocks web page.
One way to make a whiter white is to add phosphors so that the UV from the sun will not only reflect white light but also cause the phosphor to glow white.
Some of the paper IDs in my wallet have whiteners as part of their design. Maybe to make counterfeit versions easier to spot.
In the movie Revolver (IMDB) Ray Liotta's character is naked in a tanning room and his teeth just shout light.
The paper money of most countries has a number of features designed to make counterfeiting more difficult and to allow automated bill acceptors to correctly recognize the value of a bill even when the physical size of the bills are the same.
My California DL has two photographs, the large white light viewable photo and a smaller UV only version.
There are additional markings only visible under UV light.
Uranium Glass (Wiki)
Most items that glow in the dark also glow brightly under UV light. This is a good way to "charge" them.
2401191 Telescope for receiving and detecting ultraviolet light, Rosett Walter, Navy, App: 1931-10-02, (SECRET), Pub: 1946-05-28, 250/487.1; 250/372; 359/355; 359/400 - UV to visible screen is a reflector so has much less loss than a screen that works by transmission. Looks like a pair of binoculars.
How Hot Are Your Rocks? Radioactivity in Uranyl-Activated Fluorescent Minerals - combines radioactivity and UV - Facebook: Fluorescent Minerals - including uranium glass
NYT: Scientists Consider Indoor Ultraviolet Light to Zap Coronavirus in the Air, May 7, 2020 -
ASHRAE: Reducing Infectious Disease Transmission with UVGI (pdf), W.P. Bahnfleth
UV: 100 to 400 nmColumbia U: Using the Power of Light: Preventing the Airborne Spread of Coronavirus and Influenza Virus -
UV-A: 400 to 315 nm
UV-B: 315 to 280 nm
UV-C: 280 to 200 nm (254 nm UV Germicidal Irradiation).
Vacuum-UV: 200 to 100 nm.
Peak germicidal action at about 265 nm.
Low pressure Hg: 253.7 nm, medium pressure: 315 nm - special clear glass florescent tubes
peak output when lamp surface temp. is about 40 deg C. (important if lamp mounted in air duct).
Upper Room Disinfection ( UV above heads of occupants). NIOSH 2009 TB.pdf
far UVC: 207 to 220 nmBook: Airborne Contagion and Air Hygiene. An Ecological Study of Droplet Infections, William Wells, 1955 -
Nature: Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases, Feb 9, 2018,