A modular chinrest for retinal imaging

The main function of this repository is to distribute the component designs of the original chinrest. Everything is free to download and we only ask you to cite our paper XXX if you decide to use the chinrest design (or part of it) in your scientific setup.

The headrest was designed to be modular and most of the parts are 3D printable to minimize manufacturing costs. I roughly categorized the subassemblies/parts into few categories to quickly explain the reason behind the design decision and the material we chose. This is our first prototype so if you have ideas for design improvements, you can modify these parts as you please.

If you wish to have the master assembly file from Fusion 360, please contact Kari Vienola. Also if you find the chinrest files useful, consider citing our paper: http://dx.doi.org/10.1364/AO.513801 (Head stabilization apparatus for high-resolution ophthalmic imaging).

Kari V. Vienola
Researcher / University Teacher
University of Turku

Ethan A. Rossi
Assistant Professor
University of Pittsburgh

Contents

Detailed description of what is in each folder

Mounting

As we are using Velmex motorized stages for all three axes of motion, the current base plate for mounting is quite large. The mounting plate size can be modified if you keep the hole distances in the bottom the same. The two mounting brackets are made from aluminum mainly so that they can be securely mounted to the base with threaded holes.

Material used: MIC6 cast aluminum, ½” thickness

Chinrest

This consists of two parts, the sliding guide that is mounted to the base and the chinrest piece itself. The chinrest piece was designed to be moved along the z-axis (parallel to the optical axis of the incoming beam) to accommodate different head shapes. The “cupping” for the chin was done by trial and error and it can be altered if needed. Gluing a thin rubber in the chin cup will increase the friction as some 3D printed plastics might be a bit slippery. The bottom has a slot insert for metal piece that is inserted either a) gluing or b) heating up the metal piece and allowing the surrounding plastic to melt. This metal piece is meant to protect the plastic from the locking screw (not mandatory but highly suggested). The length of the dove rail can be easily extended by extruding the piece itself.

Material/parts used: standard 3D printing plastics and scrap metal/aluminum for the slot, brass insert: https://www.mcmaster.com/93738A210/

Headband

The left and right mounting brackets have t-slots machined in them with slot opening for the screw to tighten the headband to a certain height. The adapter pieces that go inside the t-slot and the headband itself can be 3D printed as one piece but as we were prototyping, we kept them separate in case material had to be changed or the headband diameter would not be correct. Brass inserts are melted into the headband for proper threads and the bottom hole are used for connecting the t-slot pieces with the headband. The top holes are for the screw that goes through the mounting bracket and locks the headband in place for the desired height. Materials used: standard 3D printing plastic, brass inserts, screws to clock the band in place

Forehead slider

The forehead slider consists of 4 pieces: tapered nut, the slider itself, the rod and the temple pad. Originally the idea was to machine the rod, but 3D printed version seemed to work just fine. The tapered nut will squeeze the rod opening the more you tighten it and provides very sturdy locking mechanism. The temple pad is just snapped in place and again, rubber or felt can be glued on to the surface if wanted.