Low Cost Digital Power meter

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142laser

Low Cost Digital Power meter

Post by 142laser »

I have for sale in excellent condition a United Detector Technology Model 351 digital Optical Power Meter with matching probe. This unit is in excellent condition and uses a standard 9V battery. Right now it is calibrated for 488 nm but I can easily calibrate this meter for 532 nm or 632.8 nm at no cost before shipping. This meter has six ranges from 2 microwatts to 200 mW and also features a switchable backlight for you holography guys (and girls). This meter includes a soft case too. Like new condition. $275 including calibration and shipping to the USA!

Phil Bergeron, 142laser, (813) 974-2378 (work) (813) 996-5114 (home) pbergero@cas<dot>usf<dot>edu
BobH

Low Cost Digital Power meter

Post by BobH »

I used a UDT S351L (I believe that was the full model number) all throughout the '80s and half the '90s. It was a very good meter for holography. The detector is samll but easy to hold and point toward the source with the detector face at the recording plane.

I made two modifications to mine. I got a shorter cable for the detector because I hate wires flopping all over the setup in the dark, and I had UDT change the switch for the backlight so it would stay on without holding it on (as was standard). This was a handheld meter, not a benchtop unit. I also made a little cradle to hold it so I could see the display better than when it was laying on the table, and kept the meter plugged in.

A very good portable meter at a very good price, for a single wavelength work.
142laser

Low Cost Digital Power meter

Post by 142laser »

HI,
You are right about all of that! The detector housing is small and easy to point to measure the reference or object beam and the readout is easy to handle. Sam Goldwasser (Sam's Laser FAQ) converted this one to standard batteries as the rechargeable ones were bad. You do have to hold the backlight switch and that is slightly inconvenient. But the meter is really like new. Another good point is the Cal Test switch. You can read out a calibration number for the wavelength so if you know say three different calibrations for say HeNe, doubled YAG and Blue 488 nm Argon you can adjust the calibration easily with a small screwdriver. I will supply numbers for several common wavelengths to less than 10% error (probably much closer). Beat that deal. :angel:
BobH

Low Cost Digital Power meter

Post by BobH »

I'd also recommend opening the detector head and guleing the detector in place insaide the housing with a couple of small tacks of epoxy. My detector gradually walked its way out of the holder for it inside the head, giving me gradually increasing power readings over about a month. I was remixing developers, using new plates, being amazed at how much power my laser was giving ("THAT wasn't it"), and spinning my wheels spending time and money. Then one day I picked up the detector head and heard a rattle! Damn! :doh:

Pushed the detector back in, the laser was at a realistic output power, and the holograms came out bright as expected for the power level at the recording plane. :dance:
142laser

Low Cost Digital Power meter

Post by 142laser »

That is funny now but not back then right? The detector is not loose and the readings are solid; this is a nice meter for the price in my opinion and I can provide calibtration at 532, 632.8, 488 and other lines upon request before shipping. :)
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