TABLE 7:

Comparison of Q′ values calculated from articles that gave values for laser power and its equivalent force.

Reference	Object being trapped	Q′ (calculated)	Stated power	Force estimated by an independent method (pN)	Wavelength used (nm)
Coated beads
Sato et al. (1991)	3-μm beads (latex)	0.18	5 mW	3	1330
Wright et al. (1993)	1-μm beads (silica)	0.017	0.1 mW	0.0056	1064
	10-μm beads (polystyrene)	0.16	0.56 mW	0.3
Svoboda and Block (1994b)	Kinesin-coated beads	0.03	62.5 mW	5–6	1064
Yin et al. (1995)	RNA polymerase–coated beads	0.05	82 mW	13.6	Not given
Simmons et al. (1996)	3-μm beads	0.12	100 mW	40	1064
Biological specimens
Ashkin et al. (1990)	Mitochondria	0.012	63 mW	2.6	Not given
Liang et al. (1994)	Chromosome fragments	0.034	264 mW	30	1064
Kurachi et al. (1995)	Microtubules	0.09	1 mW	0.3	647.1
			25 mW	7.5
Konig et al. (1996)	Sperm heads	0.16	150 mW	82	800
Kellermayer et al. (1998)	Unfolding titin	0.08	1.5 W	400	1064

Q’ values were calculated using the equation Q′ = cF/P.