Color Temperature Conversion Filter (Light Balancing Filter)

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Color Temperature Conversion Filter (Light Balancing Filter)

Color Glass Filter : List

What Is Color Temperature

If the color of a light source visually “resembles” the color of radiation emitted by a blackbody (a perfect radiator) heated to a certain temperature, that blackbody temperature is defined as the color temperature of the light source. The unit is K (kelvin). For example, the color temperature of sunlight is approximately 5500K–6500K, while that of an incandescent lamp is about 3000K.

What Is a Color Temperature Conversion Filter

A color temperature conversion filter is a colored glass filter that changes the color temperature of a light source. Its conversion capability is expressed as a numerical value called the “B–R conversion value,” with the unit mired. For example, if the color temperature of the original light source is K₁ and the color temperature of the transmitted light after passing through the filter is K₂, the B–R conversion value V of this filter is given by the following formula.

This value is positive for amber-type filters (LA series), which lower the color temperature, and negative for blue-type filters (LB series), which raise the color temperature.

Relationship Between Thickness and Conversion Capability

Color temperature conversion filters are absorption-type colored glass filters. Therefore, changing the thickness alters their transmission characteristics. When a filter (B–R conversion value: V₁, thickness t₁) is polished to change its thickness to t₂, the resulting B–R conversion value V₂ is given as follows.

In other words, by polishing and adjusting the thickness, it is possible to produce a filter with any desired color temperature conversion capability.
Please contact us if you have specific requirements.

We can also provide measured transmittance data (for a fee). Please contact us for details. (Measuring instrument: Shimadzu UV-3600)
Color temperature conversion filters are exempt from the RoHS Directive. For details, please see here (English).
Other dimensions and circular processing are also available upon request. Prices vary depending on quantity and shape.

Reference Photos

LA20 Processing example

LA80 Processing example

LA140 Processing example

LB80 Processing example

LB120 Processing example

LB200 Processing example

Material Data

HOYA　LA Series

Material	Standard Value	Color specification (Standard illuminants A)		Refractive index	Chemical charactor		Heating charactor				Mechanical charactor		Specific Gravity
Material	V(mired)	x	y	600nm	Dw	DA	Tg	Ts	α -30 / 70	α 100 / 300	Hk	FA	S
LA20	+20 ±5	0.467	0.408	1.547	2	1	505	545	89	102	520	130	2.73
LA40	+40 ±5	0.469	0.413	1.554	2	1	505	550	88	102	520	130	2.76
LA80	+80 ±5	0.490	0.415	1.526	3	1	510	560	100	113	530	130	2.67
LA100	+100 ±5	0.500	0.415	1.525	3	1	510	560	100	113	530	130	2.67
LA120	+120 ±5	0.510	0.415	1.524	3	1	515	565	99	110	530	130	2.68
LA140	+140 ±5	0.519	0.415	1.524	3	1	515	565	99	110	530	130	2.68
LA200	+200 ±5	0.545	0.411	1.529	3	1	515	565	99	110	530	130	2.68

* The listed data are standard values. As we are always improving our products, the data listed are subject to change without notice.

HOYA　LB Series

Material	Standard value	Color specification (Standard illuminants A)		Refractive index	Chemical charactor		Heating charactor				Mechanical charactor		Specific gravity
Material	V(mired)	x	y	600nm	Dw	DA	Tg	Ts	α -30 / 70	α 100 / 300	Hk	FA	S
LB20	-20 ±5	0.433	0.406	1.522	3	1	470	515	95	117	490	110	2.81
LB40	-40 ±5	0.417	0.404	1.509	2	1	460	515	92	115	490	110	2.81
LB80	-80 ±5	0.388	0.398	1.541	2	1	460	510	99	116	490	110	2.83
LB100	-100 ±5	0.380	0.384	1.534	2	1	460	505	97	114	490	110	2.81
LB120	-120 ±5	0.365	0.379	1.517	2	1	480	535	94	105	520	130	2.57
LB200	-200 ±7	0.316	0.342	1.514	1	1	480	530	92	105	520	130	2.57

* The listed data are standard values. As we are always improving our products, the data listed are subject to change without notice.

Price list

As for customized size, please contact with us first.
Adjust spectral characteristics according to glass thickness.

Dimensional tolerance: ±0.2 mm, Surface treatment: Optical polishing.

Model Number	Size	List Price*
LA20-50	50 x 50 mm	10,000 yen
LA40-50	50 x 50 mm	10,000 yen
LA80-50	50 x 50 mm	10,000 yen
LA100-50	50 x 50 mm	10,000 yen
LA120-50	50 x 50 mm	10,000 yen
LA140-50	50 x 50 mm	10,000 yen
LA200-50	50 x 50 mm	10,000 yen

Model Number	Size	List Price
LB20-50	50 x 50 mm	10,000 yen
LB40-50	50 x 50 mm	10,000 yen
LB80-50	50 x 50 mm	10,000 yen
LB100-50	50 x 50 mm	10,000 yen
LB120-50	50 x 50 mm	10,000 yen
LB200-50	50 x 50 mm	10,000 yen

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