P13552 Background Research: Non Stick Surface Materials

This document outlines characteristics of various materials that the design team is considering for initial testing.

Candidate materials for Transmissive UV optics include Fused Silica, Quartz, Vycor, some formulations of Pyrex, Sapphire and a variety of fluoride compounds.

Height errors must be very tightly

controlled for good optics.

Fused Silica (Suprasil, Spectrosil, Lithosil, etc.,)

Pros: Cheap

UV to 200 nm and through visible light spectrum

UV Grade Fused Silica is synthetic amorphous silicon dioxide of extremely high purity. This non-crystalline, colorless silica glass combines a very low thermal expansion coefficient with good optical qualities, and excellent transmittance in the ultraviolet region down to 195 nm. Transmission and homogeneity exceed those of crystalline quartz without the problems of orientation and temperature instability inherent in the crystalline form.

Crystal Quartz/ Fused Silica

It has good transmission from the vacuum UV to the near infrared. Due to its birefringent nature, crystal quartz is commonly used for wave plates.

Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light.

http://www.technicalglass.com/fused_quartz_transmission.html

Ordering: http://www.technicalglass.com/product_pages/machined_quartz/polished_items_plates_discs.html

Calcium Fluoride

n=1.46

Down to 130nm

UV performance decreases over time due to water absorption

Soft and brittle

Calcium fluoride can be used without an Anti-Reflection coating due to its low index of refraction.

Magnesium Fluoride

Single layer coating film n =1:38

Performance isn’t effected by water

MgF2 is another excellent choice for deep UV to infrared regions, with good transmission range from 0.15 µm to 6.5 µm

MgF2 is one of the lowest index infrared materials, which usually doesn’t require anti-reflection coating.

MgF2 is extremely durable compared to other materials which are transparent from the UV to the IR spectrum.

Sapphire

High cost

UV cutoff= 143

Very hard

Plexiglass:

Borofloat glass versus regular Soda-Lime glass

B270 Superwite

http://www.pgo-online.com/intl/katalog/B270.html

Visible light

Teflon film (Polytetrafluoroethylene (PTFE)) a fluorocarbon

http://www2.dupont.com/Teflon_Industrial/en_US/assets/downloads/h55008_FEP_Film_Properties_Bulletin.pdf

Would need to be attached to build surface

Good materials website index of refraction for

http://www.newport.com/Optical-Materials/144943/1033/content.aspx

These graphs compare the transmission of standard optical materials. The transmission values listed here are equivalent to "external transmittance" and takes into consideration the reflectances you get from uncoated optical elements.

Transmission of 10 mm thick fused silica, BK7, and crown glass windows.

Corning Vycor (7913)

N= 1.458 at a wavelength of 589 nm

Corning 1737 AMLCD Glass Substrate

Bulb/Projector

Sharp PG MB60X

Lamp type: 200w DC

http://www.aboutprojectors.com/Sharp-AN-MB60LP-lamp.html

http://www.mv.helsinki.fi/aphalo/photobio/lamps.html

As per Texas Instruments DMD specs, working belo 400nm, right where the near UV range starts is detrimental to the DMD chips. The most damaging process results through outgassing of sealants in the micromirror array. This is the reason why DLP projectors have internal UV filters, generally included in the UHP lamp rack.

http://www.optics.arizona.edu/optomech/student%20reports/tutorials/Tutorial1_james%20Johnson.pdf