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- Dec 12, 2012
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To celebrate having made an account here exactly 10 years ago today, I’m going to do a review of a recently acquired tunable Melles Griot 532 Argon-Ion.
Operating principal:
The core of the laser is the same as any other external mirror argon, the main difference is the HR has a tuning prism to select a single wavelength at a time by changing the prisms angle with the micrometer. The prism used is a brewster prism, this type of prism has its angles such that the light will enter and exit at the brewster angle minimizing losses to near zero. The image below shows how it is setup with laser tube brewster window on left, then prism and HR. The selected wavelength will go through the prism and be reflected perfectly back into the cavity, while other wavelengths will be reflected at an angle and not stay in the cavity. By rotating the prism the wavelength that is reflected back into the cavity can be selected.
Operation:
I am running the head from a MG 400 psu which has the same interlock as other MG170/171/176 (1-3, 6-18, 19-21)
Turn rocker switch on, this turns on the fan and cathode filament, then turn on key switch and wait. To turn off, just turn off key switch and importantly leave fan rocker switch on, (on this psu the fan will automatically turn off after a few minutes), once cooled it can be switched off.
To change the laser line just adjust the vertical micrometer (upper right side). Mine has a very nice label that gives the micrometer positions to various wavelengths which is accurate for mine. The sweep across all lines is <0.4mm (0.32mm line-line), so all lines can be reached with less than one full turn on the micrometer. The second micrometer for the horizontal adjustment is not used in wavelength selection, so it i is only used for initial alignment as it would in a normal argon-ion.
Pictures:
Video has loud audio. I couldn't figure out how to lower the volume on the video, so make sure to lower the volume before playing.
Operating principal:
The core of the laser is the same as any other external mirror argon, the main difference is the HR has a tuning prism to select a single wavelength at a time by changing the prisms angle with the micrometer. The prism used is a brewster prism, this type of prism has its angles such that the light will enter and exit at the brewster angle minimizing losses to near zero. The image below shows how it is setup with laser tube brewster window on left, then prism and HR. The selected wavelength will go through the prism and be reflected perfectly back into the cavity, while other wavelengths will be reflected at an angle and not stay in the cavity. By rotating the prism the wavelength that is reflected back into the cavity can be selected.
Operation:
I am running the head from a MG 400 psu which has the same interlock as other MG170/171/176 (1-3, 6-18, 19-21)
Turn rocker switch on, this turns on the fan and cathode filament, then turn on key switch and wait. To turn off, just turn off key switch and importantly leave fan rocker switch on, (on this psu the fan will automatically turn off after a few minutes), once cooled it can be switched off.
To change the laser line just adjust the vertical micrometer (upper right side). Mine has a very nice label that gives the micrometer positions to various wavelengths which is accurate for mine. The sweep across all lines is <0.4mm (0.32mm line-line), so all lines can be reached with less than one full turn on the micrometer. The second micrometer for the horizontal adjustment is not used in wavelength selection, so it i is only used for initial alignment as it would in a normal argon-ion.
Pictures:
Video has loud audio. I couldn't figure out how to lower the volume on the video, so make sure to lower the volume before playing.
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