L200 Higher Orders Overlap Tests with F4T5D Light

Spectra L200 Spectrograph
Higher Orders Overlap Tests with F4T5D Light

These specturms show the L200 higher orders overlap (2, 3 and 4) when using a 600l/mm grating.

The spectrums are of a hand held five inch fluorescent (Satellite F4T5D) light taken with an unpainted Spectra L200. The fluorescent light uses excited mercury atoms and therefore the spectrum has strong mercury emission lines

The bright and colorful mercury emission lines make it easy to identify the wavelengths.

4046.563 Å - violet,
4358.328 Å - violet,
5460.735 Å - green,
5769.598 Å - yellow,
5790.663 Å - yellow,
6149.475 Å - red.

See the Spectrum of Mercury Gas Discharge for a colorful spectrum diagram that helps to identify the mercury emission lines.

The camera is a very old Nikon Coolpix 990 Digital Camera afocal coupling to an eyepiece (STWA18 Wide Angle 18mm Eyepiece/Adapter ) with built in adapter threads to the camera.

Short wavelengths are on the left side of the spectrum and long wavelengths are on the right side of the spectrum. The spectrum images are one quarter size and all spectrum are cropped the same way from the original images. The spots in the spectrum images are hot pixels.

Grating order one ends at 8,064 Å and at the same time grating order 2 starts 4,032 Å for the L200 600l/mm grating at 14 degrees. Higher grating orders two and above start to overlap as is shown in the below chart and table. Excel table and graph (L200GratingOrderChartV1.0.xlsx, 50KB)

Summary
H-alpha ~6,563 Å for order two is at ~23 degrees. This angle will overlap with order three at ~ 4,300 Å. A CCD camera short wavelength sensitivity starts just below ~ 4,000 Å and continues into the infrared spectrum. Therefore, using the L200 at H-alpha (order two) will also collect order three spectrum data at ~ 4,300 Å.

The next H-alpha at order two L200 test is to use a red filter to block the order three violet spectrum from being recorded by the CCD camera.

Second Order
4358.328 Å - Violet Emission Line