Table IV. Thermal properties of transmissive optical materials

Material	Symbol	Thermal Conductivity	Thermal Expansion	Maximum Use Temp.	Comments
		mW/cm·K	·10-6/K	°C
Sodium chloride	NaCl	65	44	400	slightly sensitive to thermal shock
Potassium chloride	KCl	65	36	400
Potassium bromide	KBr	48	43	300	sensitive to thermal shock
Cesium bromide	CsBr	10	48	400
Cesium iodide	CsI	11	50	200
Lithium fluoride	LiF	40	37	400	very sensitive to thermal shock
Magnesium fluoride	MgF2	~150	11	500
Calcium fluoride	CaF2	97	19	600
Strontium fluoride	SrF2	83	18	~600
Barium fluoride	BaF2	117	18	500	sensitive to thermal shock
Silver chloride	AgCl	11	30	200
Silver bromide	AgBr	6	30	200
Thallium bromochloride	KRS-6	7	51	200
Thallium bromoiodide	KRS-5	5	60	200
Magnesium oxide	MgO	435	12	>2000
Sapphire	a Al2O3	240	8.4	1700
Crystal quartz	a SiO2	12	11	>1200
Zirconia	ZrO2	~19	~9	>1000
Zinc sulfide	ZnS	272	6.4	300
Zinc selenide	ZnSe	180	7.3	300
Cadmium sulfide	CdS	159	4.6	~200
Cadmium selenide	CdSe	?	4.9	>200
Cadmium telluride	CdTe	63	4.5	300	opaque at high temperatures
Diamond	C	23200	0.8	>700
Silicon	Si	1490	4.2	300	opaque at high temperatures
Germanium	Ge	602	6	100	opaque at modest temperatures
Gallium arsenide	GaAs	523	~4.5	~200	opaque at moderate temperatures
Silica glasses	vSiO2	14	0.6	1070	immune to thermal shock
Borosilicate glasses	BSCG	~11	~3.2	500
Fluorozirconate glass	HMFG	6.3	17	150	sensitive to thermal shock
Arsenic trisulfide glass	As2S3	2	25	~150
AMTIR-1 glass	AMTIR	2.5	12	300	unlike Ge, not opaque at hi temps
GASIR1 glass	GASIR1	2.8	17	250	unlike Ge, not opaque at hi temps
GASIR2 glass	GASIR2	2.3	16	200	unlike Ge, not opaque at hi temps
Poly-ethylene	HDPE	5	120	120	softens
Poly-methylpentene	TPX	1.7	117	160
Polyester	PET	2.4	80	~120	phase change at ~76°C
Poly-tetrafluoroethylene	PTFE	2.5	100	250
Fluorinated EPC	FEPC	2.5	95	250

Maximum use temperatures for semiconductors (e.g., Si, Ge, CdTe, GaAs) are far below maximum survival temperatures.
Their low maximum use temperatures are due to thermally generated free-carrier absorption and so are thickness-dependent.
High temperature chemical interactions with samples and window mounting materials can be a serious materials problem.
PET undergoes a phase change which can be utilized for tightening stretched-film windows with a heat gun.
These data were collected from a variety of sources, so this table probably contains errors. Use cautiously, and empirically verify critical values.
©2002 by D.W.Vidrine  « Author will not accept responsibility for any harm resulting from the use of this data! »
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