96 dB Linear High Dynamic Range CAOS Spectrometer Demonstration

• Published in: IEEE photonics technology letters Vol. 32; no. 23; pp. 1497 - 1500
• Main Authors: Mazhar, Mohsin A., Riza, Nabeel A.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-12-2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Attenuation; Bandpass filters; Code Division Multiple Access; Color temperature; digital micromirror device; Dynamic range; Frequency modulation; Gratings (spectra); high dynamic range; High pass filters; Inspection; Light sources; Luminaires; Microelectromechanical systems; Micromirrors; Optical filters; Optical imaging; Optical measuring instruments; optical MEMS; Optical sensors; Signal to noise ratio; Spectral resolution; Spectrometer; Spectroscopy; Time Division Multiple Access
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2020.3038062

For the first time, a CAOS (i.e., Coded Access Optical Sensor) spectrometer is demonstrated. The design implemented uses a reflective diffraction grating and a time-frequency CAOS mode operations Digital Micromirror Device (DMD) in combination with a large area point photo-detector to enable highly programmable linear High Dynamic Range (HDR) spectrometry. Experiments are conducted with a 2850 K color temperature light bulb source and visible band color bandpass and high-pass filters as well as neutral density (ND) attenuation filters. A ~369 nm to ~715 nm input light source spectrum is measured with a designed ~1 nm spectral resolution. Using the optical filters and different CAOS modes, namely, Code Division Multiple Access (CDMA), Frequency Modulation (FM)-CDMA and FM-Time Division Multiple Access (TDMA) modes, measured are improving spectrometer linear dynamic ranges of 28 dB, 50 dB, and 96.2 dB, respectively. Applications for the linear HDR CAOS spectrometer includes materials inspection in biomedicine, foods, forensics, and pharmaceuticals.