Mellott's VRSA Photonics SA-36
August 2014
Note: I currently work for SA Photonics and I’m responsible for a lot of our head mounted display (HMD) electronics. I also perform the system level test as well as write the demo applications when we show potential customers. I wanted to state that before jumping into a review of the SA Photonics SA-36 HMD.
The SA Photonics SA-36 is the sister HMD to the SA-65 which I reviewed here. The SA-36 has a 36 degree diagonal field-of-view (FOV). The eyepieces each contain a 1920×1200 eMagin OLED microdisplay. The OLED panels provide brilliant colors and very deep blacks. The FOV of the SA-36 was chosen intentionally to give a 0.94 arcmin/pixel resolution (30 deg. horz. FOV). This is better than 20/20 vision. Therefore the average person will never be able to see the individual pixels. Imagery on this HMD is quite impressive. Stereo 3D imagery is beautiful.
The SA-36 was built intentionally to not block out the surrounding environment, like discussed with the SA-65. The eyebox of the SA-36 is large enough so that this HMD can be used in an uplook position so that your forward view isn’t blocked. This provides a nice way of presenting remote imagery to an end user while still allowing them to interact with their environment. An example of the uplook configuration is shown below.
The SA-36 also uses the Skullcrusher head gear like the SA-65. The eyepieces are attached to an interpupillary distance (IPD) shelf which are in turn attached to a Norotos AKA2 night vision goggle (NVG) mount. The AKA2 provides fore/aft, vertical, and tilt adjustment for the HMD. The AKA2 then attaches to the Skullcrusher itself. The Skullcrusher with the AKA2 mount provides a really nice platform for mounting HMDs. Many SA Photonics HMDs use this setup as a base. Don’t let the Skullcrusher name scare you off. This is one comfortable piece of head gear. Probably the most comfortable head gear I’ve ever worn. The comfort of the head gear can be as important as the HMD itself. If you don’t think so, just ask anyone who has worn the Sony HMZ for any period of time!
An electronics pack on the back of the Skullcrusher provides the drive electronics for the eMagin microdisplays. All future SA-36 builds will include a driver with brightness buttons and a power switch on the back of the head. The electronics have dual micro HDMI inputs for video and a micro USB input for power and configuration. The dual video inputs provides stereo 3D via separate video channels. In programs like Tridef this is often called Dual Projector mode. Dual channel video is common for stereo 3D in the high end HMD world.
The SA Photonics SA-36 is probably the highest resolution HMD in the world right now. A 1920×1200 resolution display over 36 degrees diagonal FOV provides for a really high resolution experience. The very forgiving eyebox make it really easy to setup and use. That being said, a 36 degree D.FOV HMD may not be for everyone or every application. You really need to consider what it is you intend on doing with the HMD before deciding what’s more important, resolution or FOV. One day in the distant future display resolutions will be so high that you won’t have to make a resolution versus FOV tradeoff.
