Collimated Display
My research shows me that all advanced, Level-D simulators incorporate a collimated display using 3-5 channel projectors, usually DLP and LED technology to give resolutions of 1280 x 860. This optimal resolution is required for a number of reasons, one is so the detail is maintained when projected and enlarged across a 200 degree viewing area x 40 degree vertical field of view. One challenge faced with collimated displays, is where light from the projectors are first met by the BPS (back projection screen) that can filter out light by as much as 40%. To off-set this projectors need to have contrast ratios and brightness (luminums) much higher than the regular projectors, and thus a more expensive cost is associated with this.
To date, I have only read about one person successfully building a collimated display using Mylar / BoPet material, of thickness 50.2 microns (2mil) thickness. Mylar is used in many industrial products like chip/crisp packets and can be a very easy product to work with, giving a very shiny, reflective mirror surface.
Recently I have purchased the Mylar to begin design of this product and using a suction curve to bring the miror in to form, what I now need to calculate is the angle at which the mirror will sit, to carefully "mirror" the image from the BPS without error. This is the professional industry is where geometric allignment is key, however, I dont have a 100,000 budget for this, so somewhere in this document, I will need to spend a number of hours planing for this error/correction.
- Mylar / BoPet - 2mil (50.2 microns) thickness giving optimal thickness vs elasticity to work with forming the mirror
- Wooden structure built around 180 degree FOV (field of view)
- Ribs with holes, evenly spaced to create a pocket vacuum in each compartment, to even out the pressure differential between the suction point and the furthers distance out from this as a point of reference. Forumla: F=AP
- Adhesive glue for pre-form of mirror and its connection to the visual suction box (VSB).
- Suction / pressure BOX with pressure outlet to alter suction pressure on mirror. Calculation for optimum mirror angle required here.
- JIG - perhaps, cut from CNC machine, with accuracy of 1/10th.
I sourced MYLAR from a website in the USA, to trial my 1st design for a collimated display. The Mylar wasnt expensive, however what I found tricky was finding any Mylar larger than 5ft in width. Length was unlimited, I purchased 100ft in a roll, however limitations when buying personally restricts the width to 5ft, perhaps a few inches larger than but there abouts. Industrally, you can purchase roles of 10ft, however, there is a MOQ (minimum order quantity) specified by weight, and the smallest I could ever negotiate was 500lbs worth about $2500 in value. I think it's safe to say for now, I didnt buy the industrial quantity.
Here's the roll of Mylar I purchased recently:
Link: http://www.grafixplastics.com/mylar_what.asp
Eventually it will be vacuum formed to give this sort of shape and reflective quality
Cost: $95.00 for Mylar (L: 100ft x W: 56") @ thickness 2mil / 52 microns
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