Development of a lightweight camera for high altitude platform systems
David Thomson is a co-aurther of the paper 'Development of a lightweight camera for high altitude platform systems'. A link to the SPIE paper is below, together with the Abstract.
https://www.spiedigitallibrary.org/journals/optical-engineering/volume-59/issue-10/105104/Development-of-a-lightweight-camera-for-high-altitude-platform-systems/10.1117/1.OE.59.10.105104.full?SSO=1
Abstract
We describe the development of a lightweight, high-resolution surveillance camera for deployment on high altitude platform systems. The instrument is designed to operate at an altitude of ∼20 km and has an expected ground resolution of better than 120 mm with an appropriate sensor. While designed specifically for imaging at visible wavelengths, it is shown that the design is capable of diffraction-limited imaging at NIR and SWIR wavelengths up to 2.5 μm. We have combined a range of materials from aluminum and titanium alloys through to carbon fiber-reinforced plastic to produce an instrument with structural components that match the thermal expansion of the optical glasses used. The use of these materials has resulted in an instrument that weighs <2 kg, including a sensor package, and is designed to weigh <3 kg once integrated with an enclosure and actuated gimbal. The successful testing of two prototype systems is described, including several design outcomes from the program intended for implementation in advance of flight trials.
David Thomson is a co-aurther of the paper 'Development of a lightweight camera for high altitude platform systems'. A link to the SPIE paper is below, together with the Abstract.
https://www.spiedigitallibrary.org/journals/optical-engineering/volume-59/issue-10/105104/Development-of-a-lightweight-camera-for-high-altitude-platform-systems/10.1117/1.OE.59.10.105104.full?SSO=1
Abstract
We describe the development of a lightweight, high-resolution surveillance camera for deployment on high altitude platform systems. The instrument is designed to operate at an altitude of ∼20 km and has an expected ground resolution of better than 120 mm with an appropriate sensor. While designed specifically for imaging at visible wavelengths, it is shown that the design is capable of diffraction-limited imaging at NIR and SWIR wavelengths up to 2.5 μm. We have combined a range of materials from aluminum and titanium alloys through to carbon fiber-reinforced plastic to produce an instrument with structural components that match the thermal expansion of the optical glasses used. The use of these materials has resulted in an instrument that weighs <2 kg, including a sensor package, and is designed to weigh <3 kg once integrated with an enclosure and actuated gimbal. The successful testing of two prototype systems is described, including several design outcomes from the program intended for implementation in advance of flight trials.
Recently completed projects
- 760mm diameter F3 parabolic mirror for sale. The mirror is completed and ready for coating. Please contact if you wish to view through the test rig that the mirror is mounted in prior to purchasing.
- 760mm diameter F3 parabolic mirror and 212mm minor axis secondary mirror for a European University telescope
- 250mm diameter F3 Sphere as a test optic for a UK based optics company
- 610mm diameter F3 parabolic mirror for a European telescope manufacturer
- A number of small aluminium substrate optical flats for a UK based optics company
Projects under construction
- 200mm minor axis 25mm thick optical eliptical flat suitable for a large telescope
- 30 inch F3 (760mm diameter) parabolic mirror (Number 003)
- 24 inch F3 (610mm diameter) parabolic mirror
Latest 30 inch F3 mirror is now complete (February 2021)
The latest 30 inch F3 primary mirror is now complete and has been tested with the interferometer, Foucault test (Virtual Couder Screen) and on-sky using the star test on Polaris. Images on-sky are very pleasing even at high power when teh seeing condintions allow. The mirror is nw complete (12nm RMS on the surface) and ready for coating (protected aluminium). Please contact us if you wish to view through the test rig that the mirror is mounted in prior to purchasing.
New combined Polishing and Testing machine
Finally, the new combined polishing and testing machine is complete. A few images are below in the testing configuration. The interferometer is out of view in the image below when the mirror is horizontal. The lateral support, 3 point axial support and safety clips are easily removed for polishing. The mirror axially supported across the whole of the mirrors rear surface on the table during polishing and figuring. The mirror can be easily rotated during polishing to remove any possibility of astigmatism induced from the table. The table flatness is 30 microns.
The machine was designed in CAD and a number of items 3D printed. It is easily configurable for different mirror diameters. Fine grinding of a 30 inch (760mm diameter) F3 primary will begin soon. A number of these blanks are now in stock for manufacture. Future stock items will include 24 inch (610mm diameter) F3 mirrors.
Finally, the new combined polishing and testing machine is complete. A few images are below in the testing configuration. The interferometer is out of view in the image below when the mirror is horizontal. The lateral support, 3 point axial support and safety clips are easily removed for polishing. The mirror axially supported across the whole of the mirrors rear surface on the table during polishing and figuring. The mirror can be easily rotated during polishing to remove any possibility of astigmatism induced from the table. The table flatness is 30 microns.
The machine was designed in CAD and a number of items 3D printed. It is easily configurable for different mirror diameters. Fine grinding of a 30 inch (760mm diameter) F3 primary will begin soon. A number of these blanks are now in stock for manufacture. Future stock items will include 24 inch (610mm diameter) F3 mirrors.
30 inch F3 Prototype at Kelling Heath Star Party (September 2015)
Below are some images of the 30 inch (760mm diameter) F3 Prototype at the September 2015 Kelling Heath Star Party. The Telescope created a lot of interest and performed quite well considering the temporary low specification secondary mirror used. Development of a new 8 inch (200mm) minor axis secondary mirror has now been completed and the telescope works very well at all powers. The primary substrate is Supremax 33 fine annealed (53mm thick). The test rig telescope is fitted with the fabulous BETI encoder system.
Product development is still being finalised (mostly cosmetic improvements to the structure) but optical sets or orders for complete telescope systems can be requested now. Additional pre-generated and fine annealed F3 mirror blanks are now being polished. Verification of the primary and secondary mirror figures are done using interferometry analysis, Foucault testing (VSC) and star testing.
Please contact us if you are interested in purchasing a similar optical set or the complete telescope. Prices can be supplied on request.
Please note that optical sets, or complete telescopes, are only sold to the client following on-sky acceptance by the client. This can be undertaken at our facility or at the clients location (subject to transportation costs to the site of their choice). Optical sets will be demonstrated in the telescope test rig.
- 30 inch F3 Optical set (See the store for prices)
- 30 inch F3 Dobsonian Telescope. Complete with Secondary, 3 inch focuser and Mount (POA)
TTL produce bespoke optical sets and do not mass manufacture. Please contact us to discuss requirements.
