OPTICAL DESIGN

by Ming Liang

 
 

Optical Performance

Grating Parameters

Optical Tolerance & Error Budget

• Wavelength Band:     0.95 - 5 m  cover  J, H, K, L and M.
• Field of View:            long camera: 50” slit,  short camera: 100”, data acquisition: 100x10”,  long camera cross dispersion: 6”, short camera cross dispersion: 6”
• Resolution:                600 - 18,000.
• Image quality:            > 85% energy geometrically within 27 m  pixel.
• Throughput:               > 45% for 2.2 m , K band, long camera and 12.18 l/mm grating

Optical layout of GNIRS with short camera and cross dispersion prism
Offner Imager
Long JHK camera work with 10.44 l/mm grating
Short JHK camera work with 31.7 l/mm grating
Long LM camera work with 31.7 l/mm grating
Short LM camera work with 111 l/mm grating
The spot positions of the long JHK camera and 10.44 l/mm grating in J band
The spot positions on the detector of the short JHK camera and 111 l/mm grating in J band
Optical layout of the long JHK camera, 10.44 l/mm grating with cross dispersion prism
Spot diagrams of the long JHK camera, 10.44 l/mm grating with cross dispersion prism
Slit image of the long JHK camera, 10.44 l/mm grating with cross dispersion prism
Optical layout of the short JHK camera, 31.7 l/mm grating with cross dispersion prism
Spot diagrams of the short JHK camera, 31.7 l/mm grating with cross dispersion prism
Slit image of the short JHK camera, 31.7 l/mm grating with cross dispersion prism
Optical layout of the Long JHK camera with Wollaston prism
Spot diagrams of K band for long JHK camera, 31.7 l/mm grating with Wollaston prism
Short camera in data aquisition configurations
Long camera in data aquisition configurations
The pupil viewer and the pupil image on detector

• Basic grating and spectrograph parameters
• Grating rotate angles, anamorphic, blazing position and wavelength band
• Dispersion and resolution
• Spectrum location on the detector
• Relative efficiency

The 10.44 l/mm grating
The 31.7 l/mm grating
The 110.5 l/mm grating

• Optical  fabrication and alignment.
•               The rms image degradation on the detector < 5%
•               The rms image degradation on the slit           <5%
•               The worst image spot diameter degradation <7%
•               The additional vignetting    <1%

The Tolerance Analysis for GNIRS
The Tolerance Distribution
The Tolerance of the Cameras
 

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