Norland adhesive


I am looking for guidance as I know essentially nothing about lights and this forum seems like a great resource for learning.

I would like to use Norland Adhesive to adhere a thin plastic film to a piece of glass. Norland has so many different products so I am not entirely sure which I will choose, but I intend to try several of them and see what works best. The one I am eying is NOA75 which cures at 400-450 nm. Ideally, I would prefer to use one that will cure with visible light as UV light will destroy RNA (I need to preserve RNA for my experiment). Would anyone have a recommendation for a light source of sufficient strength to cure an adhesive that emits at ~425 nm?

Thank you!

Well, any cool white led has a good deal of emission around 450nm. If you want something specific to cure such 400 to 450nm glue without any risk to RNA, a royal blue emitter (basically a white led without the phosphor layer) should do. According to datasheet, XP-G3 Royal Blue emitters have a peak wavelenght range between 440 and 455nm. Recently bought one for a friend at arrow, take a peek:

These emitters can be driven up to 2A (≈7W) according to official specs, but around here we now they can take some more, namely if mounted on copper thermoelectric separated/direct thermal path boards.

Cheers ^:)

Thank you for your reply, Barkuti. In the adhesive data sheet it specifies that full curing requires 5 joules/cm^2. Is this LED capable of producing that amount of energy in a relatively short period of time? Are there handheld or bench top devices to house these types of LEDs?

Cree XP-G3 datasheet

Related emitter information. You can see the emission curve for a royal blue emitter there. Due to curve shape, centered around ≈450nm, I'll assume about half the emitted energy is usable for curing.

Bin current (350mA) minimum F2 radiant flux at 25°C is 680mW. At 85°C junction temperature this decreases to ≈93%, so let's say a minimum of 630mW at 85°C for an F2.

Now, let's say we chose to drive the emitter at 1.4A, this is 350% relative radiant flux or 2205mW, ≈2.2Js-1 , ≈1.1Js-1 useable as above said. Thus, collimating close to all this emitter output onto 1cm² will have the job done in under 5 seconds, 50 seconds for 10cm², and so on.

Around there you'll find plenty of examples of handheld devices (flashlights) which can house this led. However, distance to target and the amount of surface you want to cover matters. This is to get an idea of what sort of optics for the job. A decent smooth reflector will collimate the beam narrow with some spill, an aspheric zoomie or wide TIR torch will give a nice and smooth blanket of light. So, more input will go down well.

Cheers ^:)