CoMIC: A Compact Multicolor Imaging Camera Sunip Mukherjee Department of Physics and Applied Physics This work was supported by the UMass Lowell Center for Space Science and Technology. Design Highlights • 1U CubeSat compatible • 8 Watts power usage • 30° field of view (FOV) • 0.1° angular resolution • High optical throughput • 400 nm-900 nm operating range • Can be used with very narrow band interference filters • Exposures as low as 1ms Abstract We describe the construction and features of a compact multicolor imaging camera (CoMIC) that can be used for remote sensing in 400-900 nm wavelength range. The instrument accommodates a mosaic of optical filters that allow only certain wavelengths of light allowing CoMIC to image different segments of a scene in different wavelengths, then scanned in a push-broom fashion to image a large area in multiple colors. The choice of colors are determined by the chemical species or reaction to be observed: sodium and potassium doublet emission in this prototype. Future Plans • Customizable filter mosaic, along with the compact form factor and rugged design makes it ideal for applications such as aeronomy (study of upper atmosphere), to surface remote sensing (agriculture, oil and gas exploration etc) in the visible to near infrared range with a large number of signatures. • Higher resolution with a smaller FOV or vice-versa with minor modifications to the existing design to extend range of applications. • Planned weather balloon flight to measure airglow over a 24-hour period to augment existing instruments that measure airglow. Push-Broom Scanning As the name indicates, push-broom scanning (or on-track scanning) uses a line of detectors perpendicular to the direction of scanning. In the case of CoMIC, the field-of- view (FOV) is divided into segments of different colors, and scanning is performed perpendicular to the segments so that one point is imaged under all color segments in the instrument. Scan direction Left: Push-broom scanning concept is described (courtesy: Harris Geospatial); Right: Filter mosaic used in CoMIC, with possible scan direction. The four colors correspond to 500 nm, 589 nm, 770 nm and 700 nm from left to right. Design Principle The instrument is designed around the 1U-CubeSat form factor that restricts its mass and volume within a 1.4 kg, 10 cm cube. The filter mosaic that lends CoMIC its ability to image in multiple colors require near-normal incidence of light for optimal operation. This is achieved by placing the filter mosaic at a telecentric image plane. The filter plane is then reimaged onto a charge-coupled detector (CCD) array using multiple lenses. The telecentric configuration allows the use of very narrow band filters in the instrument. Left: Protype instrument in a 3D-printed chassis; Right: Optical design layout of the instrument. Data Acquisition • Obtains optimally bright images through automatic exposure control • Prototype instrument has four filter panes: 589 nm for sodium, 700 nm for potassium, 500 nm and 700 nm for background continuum Scan direction 1 ms exposure taken by CoMIC on a sunny day. The four filter patches are indicated in the figure using false colors. The white ellipse indicates to a tree under the 700 and 770 nm patches; dark trees under all filters but 770nm demonstrates low absorbance by chlorophylls beyond 700 nm. This scene is observed by CoMIC, whose output is displayed on the right. Back of the Detector Entrance Pupil Camera Lens Camera Electronics

CoMIC: A Compact Multicolor Imaging Camera€¦ · used in CoMIC, with possible scan direction. The four colors correspond to 500 nm, 589 nm, 770 nm and 700 nm from left to right

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Page 1: CoMIC: A Compact Multicolor Imaging Camera€¦ · used in CoMIC, with possible scan direction. The four colors correspond to 500 nm, 589 nm, 770 nm and 700 nm from left to right

CoMIC: A Compact Multicolor Imaging CameraSunip Mukherjee

Department of Physics and Applied Physics

This work was supported by the UMass Lowell Center for Space Science and Technology.

Design Highlights• 1U CubeSat compatible

• 8 Watts power usage

• 30° field of view (FOV)

• 0.1° angular resolution

• High optical throughput• 400 nm-900 nm operating

range• Can be used with very

narrow band interference filters

• Exposures as low as 1ms

AbstractWe describe the constructionand features of a compactmulticolor imaging camera(CoMIC) that can be used forremote sensing in 400-900 nmwavelength range. Theinstrument accommodates amosaic of optical filters thatallow only certain wavelengthsof light allowing CoMIC toimage different segments of ascene in different wavelengths,then scanned in a push-broomfashion to image a large areain multiple colors. The choiceof colors are determined by thechemical species or reaction tobe observed: sodium andpotassium doublet emission inthis prototype.

Future Plans• Customizable filter mosaic, along with

the compact form factor and ruggeddesign makes it ideal for applicationssuch as aeronomy (study of upperatmosphere), to surface remotesensing (agriculture, oil and gasexploration etc) in the visible to nearinfrared range with a large number ofsignatures.

• Higher resolution with a smaller FOVor vice-versa with minor modificationsto the existing design to extend rangeof applications.

• Planned weather balloon flight tomeasure airglow over a 24-hour periodto augment existing instruments thatmeasure airglow.

Push-Broom ScanningAs the name indicates, push-broom scanning(or on-track scanning) uses a line ofdetectors perpendicular to the direction ofscanning. In the case of CoMIC, the field-of-view (FOV) is divided into segments ofdifferent colors, and scanning is performedperpendicular to the segments so that onepoint is imaged under all color segments inthe instrument.

Scan direction

Left: Push-broom scanning concept is described(courtesy: Harris Geospatial); Right: Filter mosaicused in CoMIC, with possible scan direction. Thefour colors correspond to 500 nm, 589 nm, 770nm and 700 nm from left to right.

Design PrincipleThe instrument is designed around the 1U-CubeSat form factor thatrestricts its mass and volume within a 1.4 kg, 10 cm cube. The filtermosaic that lends CoMIC its ability to image in multiple colors requirenear-normal incidence of light for optimal operation. This is achieved byplacing the filter mosaic at a telecentric image plane. The filter plane isthen reimaged onto a charge-coupled detector (CCD) array usingmultiple lenses. The telecentric configuration allows the use of verynarrow band filters in the instrument.

Left: Protype instrument in a 3D-printed chassis; Right: Optical design layoutof the instrument.

Data Acquisition• Obtains optimally bright

images through automaticexposure control

• Prototype instrument has fourfilter panes: 589 nm forsodium, 700 nm forpotassium, 500 nm and 700nm for background continuum

Scan direction

1 ms exposure taken by CoMIC on a sunny day.The four filter patches are indicated in the figureusing false colors. The white ellipse indicates to atree under the 700 and 770 nm patches; dark treesunder all filters but 770nm demonstrates lowabsorbance by chlorophylls beyond 700 nm.

This scene is observed by CoMIC,whose output is displayed on theright.

Back of the Detector

Entrance Pupil

Camera Lens

Camera Electronics