Скачать или смотреть Testing a UV meter

More info at:
http://chsopensource.org/uv-meter/

It’s use­ful to mea­sure the out­put of an Ultra­vi­o­let light source when shoot­ing UV Flu­o­res­cence and UV Reflected pho­tog­ra­phy. There are a num­ber of UV meters on the mar­ket, very expen­sive. This post is about, as usual, a bud­get solu­tion that goes for $150 on eBay.
I like when­ever pos­si­ble to test my new equip­ment. I don’t have any expen­sive spec­trom­e­ters, so I’ll have to play with my fil­ters and fig­ure out alter­na­tive test­ing methods.

First, we need to check if this UV meter actu­ally mea­sure only UV light. It turns handy what said about the white LEDs in this post. I tested the UV meters with my set of fil­ters. For a recap of my fil­ters set, see here. As usual, a movie:

Let’s test it step by step.

1. With the white LED light lamp on and with­out any fil­ter, the read­ing is 10 microW. This could be due to UV, VIS and IR light. Though, we know from this post that white LED have some infrared light com­po­nent other than vis­i­ble. So, we have to find out if this read­ing is due to VIS or IR. let’s pro­ceed with another filter.

2. B+W 486. With the B+W 486 fil­ter on the lamp, read­ing is 0 microW since this fil­ter cut any IR and UV. So, we under­stand that the read­ing is not due to VIS light but to IR. Indeed, the quan­tum effi­ciency curve, pro­vided by the man­u­fac­turer, goes up until 480 nm, and doesn’t tell any­thing about the IR…we could stop our test here but let’s try the other filters.

3. Heliopan RG1000. This is a far IR pass fil­ter and read­ing is 0 microW. Indeed, the close IR from the LED lamp is cut off by the RG1000, which cut IR until 1000 nm.

4. B+W 403. Even­tu­ally, with the B+W 403 fil­ter we read 1 microW. but this is due again to the clos­est infrared light that this fil­ter allows through.

In con­clu­sion, this is a fine UV meter, we just need to put on it a X-Nite CC1 that stop IR but it’s trans­par­ent to the close UVA. We really need this fil­ter on if we are test­ing a UV lamp that emits also IR (which is the case with Wood’s glass).