Lens/Filter holder for LPM-1

[Hemlock_Mike]

I now have three filter holders for my newly recalibrated LPM-1 power meter.  I glued two 0.75" square pieces of this steel on the front of the meter and then made lens holders from 0.125 plastic.  The lens is glued lightly into a machined pocket with Elmers glue and flexible refrigerator magnets are cut and glued to the edges of the plastic.  These can be stacked because of the magnets as needed.  There's space to apply a label to each "slide".
Trouble is, these filters ask more questions than they answer.  The IR absorbtive filter seems to reflect a bunch which makes for a lower visible reading than expected.  More testing is needed.

Mike

 

[pseudonomen137]

Cool modification. I would be nice if there was a way to easily stick an IR filter in front of the lasercheck but I don't have an efficient filter large enough (I have a huge "IR filter", but it isn't good enough for lasers). What wavelength range do those Dr. Lava meters measure anyway?

 

[Hemlock_Mike]

The LPM-1 will measure about anything but they are calibrated at 473, 532, 633, 660 and 808 nM.  They come now with a glass ND-8 filter calibrated to expand the range to 1 watt.
My two IR filters have: 1. An IR pass filter which looks like black plastic passing only IR.  &  2. An Edmunds 45719 IR absorbtive glass filter which has a cutoff starting at about 700 nM.  
Trouble is that the Edmund filter reflects a portion of the green and if not accounted for could be considered as IR output in simple power calculations. I'm using all 0.50" filters to fit close to the sensor.

I won't post any power output data on any lasers until I can account for these unknowns.

Mike

 

[Hemlock_Mike]

So far, using my DL95, I have found that the Edmund IR absorbtive filter reflects 12% of the green beam using my Sper Scientific meter to monitor the reflection. With all calculations, My DL95 has either 0.65 mw of IR output or 0.55 mW of IR depending on which set of filters used. That's still 15% error but I have more figgurin' to do.

Mike

 

[stevetexas]

very nice work - good idea!!!

 

[Hemlock_Mike]

SteveT -
I got my IR filter from somewhere else - Edmunds).  SenKat gave me your part number (I think) and they were sold out.  Do you get reflection of green off your lens and is it an IR pass or block. ???

Mike

 

[stevetexas]

http://www.optics-online.com/irc.asp

Here is the link. I use the IRC21 and IRC30 filters. Typically, the IRC 21 is the one I use most (absorptive). Check out the graph they provide. There is about 5% loss with these filters... They are low wavelength (700nM and less) "pass" filters, but IR blocking filters.

You want the "r " filters (round) for your lens holder Mike - the 10mm IRC30-10R_SU filter is in stock at this time according to their website.

 

[Hemlock_Mike]

Many thanks Steve --- I'll look there.
Mike


PM TODAY ---
I ordered the two filters PLUS two lenses for a collumator.  Three items out of stock or not stocked !!  I got the IRC 30 ----- It has a very sharp cut-off curve.

Mike

 

[Aseras]

That's freaking awesome. I'm so copying that idea.

 

[Hemlock_Mike]

Aseras -

This is much easier than I originally planned and those 'frig magnets cut with scissors !!! The metal on the front of the meter is a couple pieces of steel banding strap - alrerady blued !!

Mike