Hinds Instruments - Hinds Instruments

I unplugged my blue cable while the modulator was turned on.

admin — Sun, 06 Dec 2009 22:34:35 +0000

If the blue head to head cable (or either one of the black triax cables for systems that do not have a blue triax cable) was removed during operation of the PEM, there is a good chance that your PEM will need to be returned for repair. Follow the test procedure that is on page I-v of your PEM User’s Manual to see if the PEM is functioning properly. If it is not, email Hinds Instruments for an RMA number to return your PEM system. Return shipping instructions are included in the User Manual. If you are unable to locate this, please Contact Us and we’ll provide the information.

My PEM is not providing stable retardation and/or there is noise if I look at my signal on an oscilloscope. What could be wrong?

admin — Sun, 06 Dec 2009 22:32:14 +0000

There are several possibilities. A list of questions to begin troubleshooting is:

What is your optical and electronic setup?
What is the light source you are using and the wavelength or wavelengths (in particular, are you using a laser)?
What detector are you using?
When the PEM is operating, is the limit light off, on steady or flashing? If it is flashing, what is the approximate time interval between flashes?
What is the operating frequency of the PEM? You may take this from the controller, but if you have a separate frequency meter, this is preferable.

Please Contact Us with the answers to these questions.

What is the difference between photoconductive and photovoltaic detectors?

admin — Sun, 06 Dec 2009 22:29:04 +0000

The difference between these two classifications is that photoconductive detectors use the increase in electrical conductivity resulting from increases in the number of free carriers generated when photons are absorbed (generation of current), whereas photovoltaic current is generated as a result of the absorption of photons of a voltage difference across a p-n junction (generation of voltage).

In general, photoconductive detectors have a higher frequency response, however they also have a higher signal to noise ratio. We recommend using photoconductive detectors if you are using a high-powered laser.

Can my optical head be close to an electric field?

admin — Fri, 04 Dec 2009 21:16:35 +0000

Yes. The optical head itself contains no electronic components and is safe to use in an electronic field. However, depending on the strength of the field, it may be advisable for you to have longer head to head cables so that the electronic head can be sufficiently removed from the electrical field so that performance is not affected.

Can I use standard cables in place of the cables that you provide?

admin — Fri, 04 Dec 2009 21:16:11 +0000

The cables that we provide are standard cables. However, the cables are part of the entire PEM resonant circuit. The length of any replacement cables must be precisely matched to the length of Hinds cables in order for the resonant circuit to be maintained. Hinds can provide you with replacement cables that have been designed to work with the PEM.

Are my dual coax cables interchangeable?

admin — Fri, 04 Dec 2009 21:15:43 +0000

Yes. If your PEM has 2 dual coax cables instead of one blue triax head to head cable, the 2 cables are interchangeable.

Can I use my electronic head in a vacuum?

admin — Fri, 04 Dec 2009 21:15:14 +0000

The electronics are not meant to be operated in a vacuum. The optical head itself contains no electronics and is safe to use in a vacuum. We can provide you with longer head to head cables so that the electronic head is not in the vacuum. Please click here to look at Hinds PEM vacuum options.

Can I use my electronic head with a different optical head?

admin — Fri, 04 Dec 2009 21:14:19 +0000

No. The PEM is a resonant device, with the resonant frequency being determined by the size of the optical assembly. In spite of very tight manufacturing tolerances, each optical head is slightly different in size and this results in a slightly different frequency. The controller, electronic head, and optical head are all calibrated to work together as one resonant circuit. Changing the pairing of the electronic and optical heads would change this precise calibration and PEM performance can no longer be guaranteed. If you have further questions, please Contact Us.

How close can my electronic head be to a magnetic field?

admin — Fri, 04 Dec 2009 21:13:31 +0000

Based on our testing, we recommend that the magnetic field strength at the electronic head and controller be no more than 100 gauss field. We provide an MFC option for PEMs that includes an 8 ft (244 cm) head to head cable which allows removing the electronic head and controller from a magnetic field.

Can a PEM be used to provide a steady retardation level (can they be used as static waveplates)?

admin — Fri, 04 Dec 2009 21:13:03 +0000

As the name would suggest, a PEM provides polarization modulation, that is, a changing retardation that follows a sinusoidal pattern. As such, applications that need a steady retardation level are not well suited for PEMs.