MTE UV 301 torch/flashlight review

[enricosavazzi]

A short review of this torch/flashlight, previously discussed a few times on the UVP site:

 

http://savazzi.net/p...mte_uv_301.html

[colinbm]

Thanks Enrico

That would sum up my experience too.

It had conserned me when I purchased my MTE UV301, that there were no labeling on the lamp or packaging, that it was in fact a 365nm UV lamp, & that there was no instruction sheet with the lamp to show the battery type or orientation for inserting the battery ? After emailing the company, I was assured my lamp was 365nm & which way the battery should be inserted.

 

I have some unqualified reservations about this lamp for UV photography & UVIVF, but I have more testing to do. I have shown some experiences with this lamp & others, for UVIVF on the recent thread on this forum on the Poinsettie flower, http://www.ultravioletphotography.com/content/index.php/topic/1142-poinsettia/page__fromsearch__1

 

Cheers

Col

[JCDowdy]

Enrico,

Good job on the photosafety and especially the misleading germicidal claims.

I find it disconcerting that hand held UV-germicidal products are actually marketed.

Happy Holidays!

[rfcurry (1950-2024)]

John,

 

Steripen - http://www.steripen.com/ - uses 254nm wavelengths. Now, that is dangerous.

[Andrea B.]

Enrico, that is an excellent review of the MTE and gives lots of additional good info about UV torches.

 

I hope to link more of your reviews when it comes time to update the Stickies.

[enricosavazzi]

John,

 

Steripen - http://www.steripen.com/ - uses 254nm wavelengths. Now, that is dangerous.

I find it somewhat disturbing that pictures on the Steripen web site and of its products on Amazon etc. show naked hands holding the sterilizer partly immersed in a glass of water. This would cause exposure of the skin (and eyes) to UVC, unless the UVC intensity is very low. If it is very low, then it cannot be very effective at sterilizing the water in a short time. So, a UVC exposure sufficient to sterilize with this product by damaging the DNA of pathogens across a few cm of water should also be sufficient to damage skin DNA across the dead skin layers. The only thing that could prevent this is a sufficient absorption of UVC by the water.

 

Assuming that 1-2 cm of water is enough to absorb UVC (water does strongly absorb UVC, but I don't know whether 1-2 cm is enough), then for safety the Steripen should include a water-activated switch that turns off the bulb whenever it is not completely immersed. I did not carefully check the site, but I did not find such information (and overall very little information on anything else).

 

Another possible concern is that stirring the water brings pathogens close enough to the bulb to be killed, but on a stochastic scale (i.e. some of the water may remain far enough from the emitter to remain unsterilized), so it is necessary to keep irradiating and stirring for quite a while, and pathogens adhering to the inner wall of the glass/flask may never receive a sufficient irradiation. I think the method used to sterilize pond water (forced passage in a gap only a few mm thick, between an inner quartz sleeve that contains the UVC emitter and an outer sleeve that blocks radiation) would be statistically more effective, and would be a better principle for a portable sterilizer. Of course, a plastic pump/syringe surrounding the emitter would make the device bigger, but also safer.

[JCDowdy]

Reed & Enrico,

 

Yes, that StirPEN is a good example of the type of device that I find disconcerting. In my professional opinion, the lack of any safety interlock to prevent exposure should preclude any such device from the market. Photobiological safety standards have gained stronger legal footing in recent years so hopefully the situation will improve.

[colinbm]

This business of the StirPens & StreriPens is even more interesting when you compare what a humble plastic (PET) bottle will do.

http://www.sodis.ch/methode/index_EN

I was looking around at the UV transmittance of PET bottles, seems they are good for transmitting UVA & above 300nm.

Col

[JCDowdy]

Yes, the water bottle solar water treatment has been around for some time. I personally would not trust it.

Probably better than nothing and doubtless an improvement in abject circumstances.

[colinbm]

The MTE 365nm LED light is the best lil' UV light that we have, BUT can it be better ?

The reflecter is giving a darker spot in the centre & there are two circles of different intensities.

Can this be improved on please ?

Perhaps the reflector was of a design that was suitable for an incandescent globe, that is above the bottom of the reflector & from a nearly single point, radiating 360 degrees all around. The LED is different as it is a point source at the bottom of the reflector & radiating only through 180 degrees.

Can the reflector be improved on please ?

Col

[enricosavazzi]

My specimen of the MTE torch does not project a darker center. In my specimen, the center is a light (=illuminated) area brighter than the periphery, with no darker "eye" or ring. The periphery is darker than the center, and in this sense the illuminated area consists of two circles of different intensities (but no rings). Is it perhaps possible that there are specimens with a different reflector?

 

Considering that the beam is quite narrow, diffusing it is the simplest way to make it more homogeneous. A sanded fused silica window is the most obvious material, but a UV-transmitting plastic would be more practical. There is plenty of information available on IR-transmitting plastics, but a quick googling did not turn up much on UV-transmitting plastics, except as usual plexiglas. As long as we can find a piece of thin plexiglass without added pigments (which may absorb UV even if they do not impart a visible color to the plastic), we can sand it and obtain a good UV diffuser.

[colinbm]

Hi Enrico

I have been looking over the MTE today & I have removed the top part of the torch that has the lens & reflector. To do this you need two wrenches, one on the square section of the torch body that houses the battery & one on the hexagonal nut shape around the reflectors base, where the LED is & turning the wrenches to unscrew these two parts of the torch. This threaded join is glued together, but not too difficult to undo with the wrenches. This will then expose the LED, which is sealed in its own clear cover, & the top section with the reflector & lens can be put aside.

You can now still use the MTE as before, but now you can get the LEDs light closer to the subject, with an increase in the power (brightness) of about 1/3rd. The LEDs light spread is still narrow enough, but now evenly spread, with no concentric rings of different brightness.

The LED appears to have a spread of 120 degrees, which is OK considering how close the torch needs to be to the subject, in my case with a flower head for UVIVF, the torch is about 20 to 25mm from the flowers centre.

I will be buying a couple more of these MTE 301 UV 365nm torches, ASAP.

Col

 

 

MTE 301 UV 365nm, without the top reflector & lens housing.

[JCDowdy]

............There is plenty of information available on IR-transmitting plastics, but a quick googling did not turn up much on UV-transmitting plastics, except as usual plexiglas. As long as we can find a piece of thin plexiglass without added pigments (which may absorb UV even if they do not impart a visible color to the plastic), we can sand it and obtain a good UV diffuser.

 

Enrico,

An clear acrylic CD case is acceptably UV transparent. Heat the blade of an E-acto knife or metal scalpel in an alcohol or gas Bunsen burner and it cuts like butter and the melt bead can be shaved off easily. For sanding as a diffuser which would be better, course or fine grade abrasive?

[Andrea B.]

Edmund Optics has a variety of diffusers. Maybe something there would be useful.

http://www.edmundoptics.com/optics/windows-diffusers/optical-diffusers/

[enricosavazzi]

Interesting to know that the head can be unscrewed and the LED exposed. I added an update to my review, since this can be quite useful in the lab. In the field, a diffuser can be preferable because it achieves a narrower beam and protects the chip.

[colinbm]

From Russia with love :D

 

[colinbm]

There is no rest for the wicked...........

I'll have to progress out from this laundry studio.

I have made another mod to the humble MTE UV 301 LED torch.

Now after removing the reflector & lens housing, my brain wouldn't let me rest, bless it.

I found a discarded cheapy LED torch that just happened to have the same thread to the MTEs head thread.

I made this bit into a filter holder for a U340 filter that I inadvertently broke the other day, so now I am a happy chappy & I hope to leave this poor torch alone now.....

Col

 

 

MTE UV 301 LED torch, shortened in front, with the original head behind & the new U340 filter holder on the left (particularly used for UVIVF photography). You can see how much closer you can get the light to the subject.

 

 

MTE UV 301 LED torch, shortened on the right, & the new U340 filter holder on the left (particularly used for UVIVF photography).

 

 

MTE UV 301 LED torch, with the new U340 filter holder installed (particularly used for UVIVF photography).

 

Time for a cuppa :D

[Andrea B.]

Alllllriiiiiight Col !! Way to go !! Now we will all want one of the Col-Mods. :) :D

 

Go make some cool fotos.

[colinbm]

Thanks Andrea, we are getting there.......baby steps.....one step at a time :)

Col

[JCDowdy]

Looking good with that U-340 on your LED!

 

Now stack a S8612 or BG-type filter on that and you will super clean!

 

I have used my 52mm U-360/S8612 stack on a 3-LED medium base 110V 365nm source and it makes the 99% Spectralon look like a 5% Spectralon!

[colinbm]

Thanks for the tip John, will do.

What is the 3-LED medium base 110V 365nm, please ?

Col

[JCDowdy]

Thanks for the tip John, will do.

What is the 3-LED medium base 110V 365nm, please ?

Col

 

It is not a flashlight (torch as y'all call it) it screws into a regular medium base light bulb socket and must be plugged into the wall (110-120V AC here in USA).

​Mine actually measured at 375nm so it is only just barely in a "365" bin