DIY UV light meter for alternative photographic processes

[meditant]

I practice a number of alternative process kallitype, pt / pd, saline and albumen paper, cyano, collodion ... I have a well equipped lab or things are clear, I know my exposure time with my insoleuse UV and my protocols even if it evolves are validated. But I wanted to make large prints and my insoler is limited to 40x50cm, I have more room to make a larger and sometimes I want to make demos out of the lab and suddenly it's complicated. In addition to the arrival of good weather I wanted to leave the lab and see if there was a difference in rendering between artificial UV and natural light, the problem is that the expo time with non-POP processes are quite difficult to evaluate, I practice a lot of kallitype with Gold or Pt / Pd toning and the eye, even if the expo is good or not, it is mission impossible. I wanted to find outside the opportunity to control the exposure for these processes and not lose my calibration work in the lab.

It was therefore necessary that I could recover the good process exposure value of my insoleuse in the lab and apply it outside or the conditions are very variable depending on the day, but also during the expo time, a cloud that pass and it changes the deal. So I created this device a kind of UV light meter to meet my needs.

I have finalized the beta version of my UV light meter for alternative processes, it allows me to make exhibitions out of the lab in daylight, the electronic and computer part is finalized and fully functional, I'm on modeling the box to finalize this project, even if I continue the test phase and still brings some improvements.

Regarding the overall operation, on the home screen we have the current UV unit that allows to choose a place for the printing frame, I have for the occasion defined a UV unit value (UUV). A UV Live menu allows to know the number of UUVs over a period of time, a count of hours / minutes / seconds begins and the UUV is incremented (the sampling frequency is configurable) this feature allows to know the number UUV needed for good exposure of a process, but also to expose if you stay close and wait for the UUV corresponding to your correct exposure. When you start a new process, you can simply exchange the number of UUVs with other users, it gives a good basis of work knowing that variations in chemistry and procedure can cause slight variations. If you have an insolvent and an already defined protocol, you get the number of UUVs needed for your process, chemistry and protocol.

It is possible to configure with the menus three different processes, one defines the name of the process and the number of UUV for a correct exposure. This data is saved.

For the exposure with countdown the function Timer UV allows to select the process, one recovers automatically UUV necessary for the good exposure which one has been configured. The beginning of the expo is started, the analysis is done in real time according to the defined sampling frequency and an evaluation of the remaining time is displayed. The measurement obviously takes in real time the UV variations. We have a PAUSE function to possibly move the printing frame (to cover during the break) to a more or less sunny area if we do not want the exhibition to continue during the trip. When the exposure is good, an audible alarm sounds. It only rained to cover the chassis and develop.

I have also integrated a calibration feature that allows sensor calibration, definition of UUV sensitivity scale and definition of sampling frequency (UUV analysis every x milliseconds)

I did tests with different weather conditions and printing frame moves during the expo which resulted in variations of the expo from 1 to 30, and for now all the expos are perfect.

Here are some specificities:

UV sensor with a sensitivity range between 280 and 390nm and a peak between 310 and 370nm
LCD display 2 backlit lines
5-key keyboard
End of Expo warning buzzer
9v battery power
Software update via USB

Here are some pictures of version 1 beta in action, the final version will be slightly different and more compact.
176039

[bob carnie]

I want the final version when you complete, I see the need for this...

should ask is there a current commercial unit that you are aware of??

[Pere Casals]

UV sensor with a sensitivity range between 280 and 390nm and a peak between 310 and 370nm
LCD display 2 backlit lines
5-key keyboard
End of Expo warning buzzer
9v battery power
Software update via USB

Here are some pictures of version 1 beta in action, the final version will be slightly different and more compact.


Nice DIY, IMHO it looks it should work like a comercial one, and at a fraction of the cost.




should ask is there a current commercial unit that you are aware of??

$190, new, UV250-410nm UV Integrator Radiometer UV Energy Meter Tester UV-150

(https://www.ebay.com/itm/UV250-410nm-UV-Integrator-Radiometer-UV-Energy-Meter-Tester-UV-150/183020803251?hash=item2a9ce3d4b3:g:xu8AAOSwFmxaXcl0)


I was to buy it for my first Carbon tests, but I use Luxmeter Android App for relative measurements, I place an UV pass filter for UV photography on the phone sensor. I plan to calibrate it with a Ocean Optics USB 2000 spectrometer, but this still pending.

Smartphones usualy have a calibrated photocell in the face to adjust screen auto-brightness, Luxmeter apps uses that sensor, it is not an "scientific" instrument because it's quite directional, and of unknown spectral sensitivity, but good enough to calibrate a personal process, single problem is that is if you change smartphone you should reference the old readings to the new ones, but anotating readings from particular light source irradiation.

Another thing is that depending on the spectral power distribution of UV light (more 395nm or more 300nm...) the effect in the alternative process may vary for the same J/cm2 irradiation. Today we have cheap 100w UV leds of 395nm, more expensive for 365nm, anyway by using an spectrally stable light source then the relative readings have to be meaningful. Note that 100w UV is a lot, owe may need to throw a lot of HID power to get 100W UV...


Another choice that don't have the integration feature, just the instant power, that may be enough if measuring time:

$43 AMAZON: TOPCHANCES High Precision UV Strength Tester UV

A bare $30 luxmeter (AMAZON: Luxmeter Epsilont 2000) with a UV pass filter on it

Search for uv pass filters: https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1311.R1.TR3.TRC1.A0.H0.Xuv+pass+.TRS0&_nkw=uv+pass+filter&_sacat=0


This is the $190 integrator:

UV250-410nm UV Integrator Radiometer UV Energy Meter Tester UV-150

176040

　

Brief introduction:

1. The UV-Integrator is used to measure UV energy and UV does of different light sources, especially on printing machines. It is ideal to ensure quality control of printing and drying process.
2. The UV-150 tester is a high quality UV measuring instrument. It is used to measure UV energy of different light sources, especially on printing machines. It is ideal to ensure quality control of printing and drying processes.
3. Small size, heavy duty pass-through Integrator with a diameter of 90 mm.
4. It is reliable and simple to use.
　

Specification:

Technical Data:

Spectral range: UV 250- 410 nm
Measuring range: 0 to 5,000 mW/cm2
Display: 6-digit LCD
Display range: 0 to 999,999 mJ/cm2
Power source: long life 3.6 V Lithium Battery
Power consumption: 100 uA
Battery service life: 10,000 hrs
Dimensions: Diameter(90 mm), Height (12 mm)
Weight: approx. 5.25 ounce (150 grs.)
Temperature range: 0 to 70 Centigrade
Heat protection: Heat shield on back plate
Base Accuracy: +-5 %
While on the conveyer belt, the UV-Integrator 150 can withstand 90-100° Centigrade for up to 10 seconds

Suitable equipment: UV UV dryer, exposure machine, conveyor belt, UV lamp, UV curing machine and other equipment, UV energy detection.

　

[bob carnie]

thanks Pere

[domaz]

Very nice looking. I noticed Sparkfun has a nice looking UV sensor (https://www.sparkfun.com/products/14264) with lots of code examples and documentation. Been meaning to make one but have been a bit busy testing alternative Carbon print sensitizers lately.

[Tin Can]

Here's the one I bought.

http://www.lightmeasure.com/

[meditant]

Thanks for your return.

I do it for me but if some people be interested a can make a mini series.

When I finished the final version a make a presentation film.

I have already some ideas for version 2

[Pere Casals]

Let me suggest interesting features that would possible with a switchable filter/sensor, by replacing the filter on the sensor it would measure UV for alternative, G-B for variable contrast paper calibration, lux·second to make sensitometric film calibration, or even working on GG as spot metering like a probe meter...

Same hardware, just some software modes and switchable filter/sensor...

[Eric Woodbury]

I'm curious about a couple things here. My reason is I have a bunch of MetroLuxs that I'm going to sell cheap. They are the leftover stock. These are light integrating timers for coldlight sources. With a different photo-diode, MetroLux could be used for UV. We've had a few customers over the years do this. Meditant, what is your photodetector? Here's a UV photodiode that isn't too expensive. It's unfiltered, but I'm not sure that makes a difference to your process.

https://media.digikey.com/pdf/Data%20Sheets/Photonic%20Detetectors%20Inc%20PDFs/SD012-UVA-011.pdf

The other question is what kind of glass do you use in your print frames? I've always heard that "glass" doesn't pass UV. I know you can't get sunburned in a glass greenhouse.

Thanks,
EW

[Pere Casals]

The other question is what kind of glass do you use in your print frames? I've always heard that "glass" doesn't pass UV. I know you can't get sunburned in a glass greenhouse.

Thanks,
EW

Common window clear glass allows to pass some 75% of sunlight's UVA, but blocks UVB. UVB is responsible of skin sunburn.

UVA (320-400 nm), UVB(290-320 nm) and UVC (200-290 nm). 96.5% of the UV in sunlight is UVA, UVC is effectively filtered out by the ozone layer. UVB is only 3.5% of total UV in sunlight.

So common clear glass only blocks 1/4 of the UVA in an alternative process. Some window glass may have coatings blocking UV, also tinted green glass blocks a lot of UVA IIRC.

[Drew Wiley]

For printing purposes, UV integrators also have to handle a lot of potential heat too. I think a dedicated unit would have real advantages in this respect, not to mention that high-UV is a form of torture to many plastics etc.

[Drew Wiley]

If you don't think common window float glass doesn't pass a lot of UV, just set a color print in window of direct sunlight for a few months, or even bright fabric. We all know what that does! - written while I'm wearing specially coated reading glasses which mitigate computer and neo-lighting UV and excessive blue.

[Tin Can]

All I know, which is little, is about 50 very serious Alt Process printers bought the one I bought. Follow the herd. I already posted the link. The maker resumed production due to high demand.

I bought one to use in Sunshine and to be able to adjust print times to changing Sunshine UV content, by sky condition, the angle of sun and distance. Meaning clouds or not and time of year.

Where I used to live I could not use the Sun, as anything left outside was stolen in moments. Now I seem to have a bit of privacy, pronounced in the English manner.

I have a porch with south and west vistas. The Darkroom is 20 ft away.

I know OP is proposing his DIY, and I think you all know I like DIY, but if off the shelf works, DIY may be the long road.

OP please carry on. Sorry to interrupt. I have a saying, Never stop a man, woman or child from working. They are so hard to restart.

[meditant]

I use ML8511 sensor with a good spectal response near 360nm.

A glass stop a part of UV but all the printing frame have a glass and work with alternativ photography that's used UV, the UV blocked by the glass it's not in the used UV range of processes. In my printing frames i use standard basic home glass.

The alternatives process i use to have a sensibility at 360nm like this sensor, the UVB influence is poor in this case and in the final version i place a glass behind the sensor to protect and have the same configuration as the printing frame.

Thanks for your comments

[Jim Noel]

I want the final version when you complete, I see the need for this...

should ask is there a current commercial unit that you are aware of??
Yes there is a current commercial version.
I probably would get in trouble if I gave you the name and website.

[Tin Can]

Jim, we can post some things. eBay is the big no-no, I believe.

Again Bob Carnie, http://www.lightmeasure.com/

[bob carnie]

I appreciate your undying patience with me Randy , I am getting old and fragile and forget many things.

[Tin Can]

I appreciate your undying patience with me Randy , I am getting old and fragile and forget many things.

You are doing fine, keep up the good fight. :)

[bob carnie]

this meter looks shit hot by the way I am goin to get me one of these suckers

[Tin Can]

I sure hope it works for you or I will rue the day...

[John Jarosz]

https://www.amazon.com/Finlon-Checker-Ultraviolet-SmartLab-Smartphone/dp/B072P33ZWQ

https://www.amazon.com/dp/B0722WKP73/ref=sspa_dk_detail_4?psc=1

[meditant]

It's cool tools but you just have the UV during the measurement, if the UV doesn't change during the exposure with a aback of process, UV Level and time that's working but, if the condition change during the exposure you need to recalculate the exposure with many parameters, x secondes at UV x + x seconds at UV y....a cloud pass...transferred my printing frame to shadow to change the render... It's good tools for skin and UV cabin but I am not sure it's fully functional for alternative photography.