Solar magnetograph employing integrated diode arrays

Area of Science:

• Solar Physics and Astrophysics
• Instrumentation and Detector Technology

Background:

• Solar magnetographs are crucial for studying the Sun's magnetic field.
• Accurate detection of weak photospheric magnetic fields requires sensitive instruments.

Purpose of the Study:

• To describe a novel solar magnetograph system.
• To evaluate the performance of integrated diode arrays as detectors for solar magnetic field measurements.
• To assess the detector's suitability for low-light level sensing.

Main Methods:

• Utilized a solar magnetograph coupled with a 1.5-m telescope.
• Employed a pair of self-scanning 512-element integrated diode arrays as detectors.
• Characterized photometric properties including Modulation Transfer Function (MTF), dark current, readout completeness, and noise.

Main Results:

• Detected photospheric flux as low as 5x10^16 maxwells (DeltaI/I = 3x10^-4 at 0.8688 microm).
• Measured detector noise equivalent to 950 electrons at the input with an integrating preamplifier.
• Demonstrated low noise and cooling characteristics when operated near liquid nitrogen temperature.

Conclusions:

• The described solar magnetograph effectively detects weak photospheric magnetic fields.
• The integrated diode array detector exhibits excellent performance at low light levels.
• The detector shows significant potential for future low-light astronomical sensing applications.