Camera

NOTE

The pinhole system for the camera was decided to not provide the highest possible image quality, and so it a system providing a lens optic was preferred. The commentary on this design can be found on the Lens Optic camera page.

Requirement

System has to have two main stage. An optic, such as a lens, followed by a detector. The detector is a chip, CCD or CMOS, which picks up the focused light from the optic. Typically, previous missions have flown lenses, such as Aalborg.

Dr Bannister has suggested that for the MRR, it would be best to have two possible designs, one for an in built lens and one for the pinhole system.

Recent Progress

As of 12/02/2009

Documents

As of 19/11/2008

Omnivision

Another CMOS chip has been found that is just $59 and is already mounted on a board that has an I2C interface and 16bit RGB imaging. The chip requries a 5V input, however. A specification document is available here.

Sensor Pixels Pixel Size (microns) Image Area (mm) Scan Mode Minimum Illumination Voltage (V) Power Requirements (mW)
OV7610 640 x 480 8.4 x 8.4 5.4 x 4 progressive
interlace
20 lux at f1.4 (3000K) ±5 200mW Active
100μW Standby

Initial Design

After the meeting yesterday (17th October), current design for the camera is to produce a pin hole camera. This will save on room and mass, when compared to having a lens optic. From this model, it is assumed that the light will enter the aperture and leave at a maximum angle of 45o from the normal to the aperture plane. After talking to Dr Bannister, he believes such a system is faesible, but the space and mass reduction would be minimal. The link below is the calculation for light levels.

Optical Photon Flux

The dimensions of the camera are modelled in the next page:

Pinhole Camera Dimensions

The ground coverage and resolution of the pinhole system is found on the page below (resolution to follow once a CMOS sensor has been chosen)

Pinhole Camera Ground Coverage

Previous missions

To study the CMOS sensors used in previous missions, I looked at two particular examples. These were the Aalborg Cubesat, and the University of Tokyo Program, CUTESAT-1.7 (#1 &#2). To save clutter on this main page, I've put the information on the missions and their suppliers on separate pages below:

Aalborg and Devitech
Cutesat-1.7 and Sharp

Cypress

The main ESA supplier of CMOS sensors is Fill Factory, who when found on the internet redirect you to a company called Cypress. They have two CMOS sensors that are designed specifically for the radiation environment of space. These are in the STAR-1000 range. The page for these is in the link here.

There's a link on this page that gets up a very promising looking technical document. Within this, there are two chips specified, both are optical, monochrome CMOS sensors that are radiation hardened and treated specifically for the space environment. Out of these I would recommend the STAR-1000BK7 over the STAR-1000 as the temperature range is better. This temperature range is improved by a glass cavity filled with N2 gas. This increases the the range from 0-60oC to -40-85^o^^C.

Information on STAR-1000 and STAR-1000BK7

CMOS Sensor Pixels Pixel Size (microns) Array Size (mm) Chip Size (mm) Pixel Output Rate (MHz) Radiation Tolerance (kRad) Temperature Range (oC) Voltage (V) Power Dissipated (mW)
STAR1000 1024 x 1024 15 x 15 15.36 x 15.36 12 >250 0-60 5 <350 with ADC, <100 without
STAR1000BK7 1024 x 1024 15 x 15 15.36 x 15.36 12 >250 -40-85 5 <350 with ADC, <100 without

Documents

For the science requirements document for the pinhole camera, please click here. The text in red is the information that I was least sure on at the time of writing.

Links

Payload Homepage

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